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U ovom radu smo pomoću tehnike depozicije atomskih slojeva (ALD) narastali tanke filmove cinkovog oksida koje smo dopirali s bakrom, s ciljem poboljšanja fotokatalitičke aktivnosti materijala pod djelovanjem simulirane sunčeve svjetlosti. XPS i SIMS analize su pokazale povećanje udjela bakra u uzorcima narastanih s većim brojem ALD ciklusa bakrovog prekursora. Također, iz fotoemisijskih mjerenja je uočeno da je u uzorcima impregniranim s Cu, bakar prisutan kao Cu+, dok kemijsko okruženje Zn atoma ostaje nepromijenjeno. SEM ispitivanja su pokazala promjene u površinskoj morfologiji uzoraka nakon uvođenja bakra u strukturu ZnO. Ispitivanja fotokatalitičke aktivnosti su provedena mjerenjem degradacije otopine metilenskog modrila pod djelovanjem simulirane sunčeve svjetlosti. Rezultati pokazuju da svi filmovi impregnirani s Cu (osim uzorka s najvećim udjelom bakra) imaju bolju aktivnost u odnosu na čisti film ZnO., In this work, we used the atomic layer deposition (ALD) technique for the growth of zinc oxide thin films doped with copper, in order of improve the photocatalytic activity of the material under the simulated sunlight irradiation. XPS and SIMS analyzes showed the increase of copper conentration in the samples grown with higher number of ALD cycles of the copper precursor. In addition, photoemission measurements show the presence of Cu (I) oxidation state of copper, in the doped samples, while the chemical environment of Zn atoms remains unchanged. The introduction of copper in the ZnO structure changes the surgace morphology of samples, as revealed with SEM analysis. Photocatalytic activity was determined by measuring the degradation of methylene blue solution under the irradiation of simulated sunlight. The results show that all Cu-impregnated films (except for the sample with the highest copper content) have better activity compared to the pure ZnO film.

U ovoj doktorskoj disertaciji pulsna laserska ablacija u vodi korištena je za sintezu nanočestica titanovog dioksida i cinkovog oksida koje imaju jaka fotokatalitička svojstva. U tu svrhu korišten je nanosekundni laser Nd:YAG osnovne valne duljine 1064 nm. Razne eksperimentalne tehnike (XRD, XPS, TEM/SEM, UV-Vis, Raman) su primijenjene za karakterizaciju dobivenih nanočestica kako bi se odredila njihova kristalna struktura, optička svojstva, oblik i distribucija po veličini. Razvijena je jednostavna metoda za određivanje koncentracije laserski sintetiziranih nanočestica u vodi, a u njoj se koriste podaci o volumenu ablacijskog kratera i raspodjela nanočestica po veličini. Metoda je testirana na nanočesticama titanovog dioksida i provjerena pomoću Beer-Lambertovog zakona. Pulsnom laserskom ablacijom titana su dobivene načestice titanovog dioksida, koje su, nakon zagrijavanja u vodi na 90°C, kristalizirale i pokazale jaču fotokatalitičku aktivnost s obzirom na UV i vidljivo zračenje nego P25 čestice. Fotokataličnost nanočestica određivana je mjerenjem brzine fotodegradacije raznih organskih otapala (Methylene Blue, Rhodamine B) pod UV ili vidljivim zračenjem u njihovoj prisutnosti. Mjerena je ovisnost fotokatalitičke aktivnosti nanočestica cinkovog oksida o njihovoj koncentraciji, početnoj koncentraciji i vrsti organskog bojila, a dobivene ovisnosti su teorijski objašnjene. Razvijena je metoda za sintezu dopiranih nanočestica pulsnom laserskom ablacijom u vodi, na način da se u njoj ablatira meta na koju je prethodno u pulsnoj laserskoj depoziciji naparen film materijala za dopiranje. Na taj način su dobivene nanočestice cinkovog oksida s različitim udjelima srebra i pojačanom fotokatalitičkom aktivnošću koja je najveća na izmjerenom optimalnom masenom udjelu srebra 0.32%. In this PhD thesis pulsed laser ablation in water is used for synthesis of titanium dioxide and zinc oxide nanoparticles with strong photocatalytic properties. For that purpose the nanosecond laser ND:Yag with basic wavelength at 1064 nm is used. Various experimental techniques (XRD, XPS, TEM/SEM, UV-Vis, Raman) are performed for the purpose of characterization of synthesized nanoparticles in order to determine their crystal structure, optical properties, shape and size distribution. The simple method for determination of laser synthesized nanoparticles concentration in water is developed, in which the ablation crater volume and nanoparticles size-distribution data are used. The method is tested for titanium dioxide nanoparticles and verified by using Beer-Lambert law. Titanium dioxide nanoparticles are synthesized by pulsed laser ablation of titanium target and it is shown that they crystallized after heating in water at 90°C and developed large photocatalytic activity in the presence of UV and visible light when compared with P25. Photocatalytic efficiency of nanoparticles was calculated by measuring the photodegradation rate of different dyes (Methylene Blue, Rhodamine B) under UV or visible light and in their presence. A dependence of zinc oxide nanoparticles photocatalytic efficiency on their concentration, initial dye concentration and dye type was measured, and obtained relations are theoretically explained. The method for laser synthesis of doped nanoparticles is developed, in which pulsed laser ablation in water is used for ablation of target that is previously coated by dopant material using pulsed laser deposition. In this way the zinc oxide nanoparticles with different silver ratios are synthesized, and they are shown to have improved photocatalytic efficiency, which is the largest at the measured optimal silver ratio 0.32 wt %.

The application of TiO 2 photocatalysis in various environmental fields has been extensively studied in the last decades due to its ability to induce the degradation of adsorbed organic pollutants. In the present work, TiO 2 powders doped and co-doped with sulfur and nitrogen and modified with platinum were prepared by particulate sol-gel synthesis. PXRD measurements revealed that the replacement of HCl with H 2SO4 during synthesis reduced the size of the crystallites from ~ 30 nm to ~20 nm, increasing the surface area from ~44 m2/g to ~80 m2/g. This is consistent with the photocatalytic activity of the samples and the measured photocurrent behavior of the photocatalysts. The results showed that the prop- erties of the powders (i.e., surface area, crystallite size, photocurrent behavior) depend strongly not only on the type but also on the amount of acid and dopants used in the synthesis. Doping, co-doping and modification of TiO 2 samples with nitrogen, sulfur and platinum increased their photocatalytic activity up to 6 times. Zaradi zmožnosti razgradnje adsorbiranih organskih onesnažil se fotokatalizator TiO2 v zadnjih desetletjih veliko preučuje za različne okoljske aplikacije. V tem delu predstavljamo z žveplom in dušikom dopirane oz. kodopirane ter s platino modificirane prahove TiO2, ki smo jih pripravili po koloidnem sol-gel postopku. PXRD meritve kažejo, da zamenjava HCl s H2SO4 med sinteznim postopkom zmanjša velikost kristalitov iz ~30 nm na ~20 nm, pri čemer se poveča tudi specifična površina iz ~44 m2/g na ~80 m2/g. Opažanja korelirajo z izmerjeno fotokatalitsko aktivnostjo vzorcev in izmerjenim fototokom. Rezultati kažejo, da so lastnosti prahov (specifična površina, velikost kristalitov, obnašanje fototoka) odvisne ne le od vrste uporabljene kisline, temveč tudi od njene količine in uporabljenega dopanta. Dopiranje z žveplom, kodopiranje z žveplom in dušikom in modifikacija prahov TiO2 s platino povečajo fotokatalitsko aktivnost tudi do šestkrat.

Kobalt je rijedak i skup kemijski element koji zbog svojih specifičnih svojstava u modernome svijetu pronalazi mnogobrojne primjene. Opće je poznato da je otrovan za ljude te da ima štetan utjecaj na okoliš te se stoga njegova uporaba pokušava svesti na što manje količine. Jedna od čestih primjena kobalta je proizvodnja pigmenata, budući da određenim kemijskim spojevima daje izrazito plavu boju. Kobaltno plavo jedan je od najvažnijih anorganskih plavih pigmenata. Ovaj rad bavi se ugradnjom kobalta u strukturu vilemita te tako pripravila čvrsta otopina koja ima boju poput kobaltno plavog ali ne predstavlja toliku opasnost po okoliš. Sol-gel sintezom pripremljeni su uzorci čistog vilemita te vilemita dopiranog sa s 0, 5, 10 i 15 mol% kobalta te su ispitana strukturna, termička i optička svojstva dobivenih produkata. Vilemit je pripravljen s dva seta prekursora; najprije s cink (II) acetatom i kobalt (II) acetatom, a kasnije s cink (II) nitratom i kobalt (II) nitratom. Uzorci su žareni na temperaturama od 800 do 1100 °C. Provedene su rendgenska difrakcijska analiza (XRD), infracrvena spektroskopija s Fourierovom transformacijom (FTIR), UV-Vis difuzna refleksijska spektroskopija DRS, kombinirana termogravimetrijska i diferencijalna toplinska analiza (TGA/DTA). Cobalt is a rare and expensive chemical element that due to its specific properties, finds numerous applications in the modern world. It is generally known as an element toxic for humans and hazardous for the environment and therefore its use is being reduced to the smallest amount possible. One of the common applications of cobalt is that it is used as a pigment component due to its extremely blue colour in some chemical compounds. Cobalt blue is one of the most important inorganic blue pigments. This master's thesis deals with the incorporation of cobalt into the willemite structure in order to prepare solid solution with colour similar to cobalt blue but with reduced threat for environment. The sol-gel synthesis of willemite with different precursors and concentrations of cobalt was carried out, and the structural, thermal and optical properties of the obtained products were examined. Willemite was prepared with two sets of precursors; first with zinc (II) acetate and cobalt (II) acetate and later with zinc (II) nitrate and cobalt (II) nitrate. Samples of willemite doped with 0, 5, 10 and 15 mol% of cobalt were prepared. The samples were annealed at temperatures from 800 to 1100 °C. X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy DRS, combined thermogravimetric and differential thermal analysis (TGA/DTA) were performed.

Cerij je jedan od elemenata rijetkih zemalja. Njegova jedinstvena svojstva proizlaze iz nepopunjene 4 f orbitale i kontrakcije lantanoida te posjeduje dva oksidacijska stanja: +3 i +4. Prijelazom između Ce4+ i Ce3+ oksidacijskog stanja ne dolazi do narušavanja stabilnosti floritne strukture pa u CeO2 može doći do promjene udjela kisika u ovisnosti o promjeni temperature, tlaka, električnog polja i prisutnosti dopanata. Transport kisika u kristalnoj rešetki CeO2 rezultat je stvaranja točkastih defekata. U ovom završnom radu sintetizirano je 4 uzorka koristeći ultrazvučno potpomognutu sintezu, a njihova svojstva su ispitana koristeći IR spektroskopiju, termogravimetrijsku analizu te rentgensku difrakciju na prahu. Fotokatalitička aktivnost sintetiziranih uzoraka ispitana je na razgradnju dva organska bojila koristeći UV/VIS uređaj. Cilj ovog rada bio je utvrditi na koji način dopiranje CeO2 utječe na njegovu fotokatalitičku aktivnost.

Cerijev(IV) oksid (CeO2) jedan je od najvažnijih oksida lantanoida te se intenzivno primjenjuje u različitim područjima od poliranja, proizvodnje i skladištenja energije, zaštite okoliša do najistraživanije katalize. Svojstvo CeO2 ključno za primjenu u katalizi je sposobnost parcijalne redukcije Ce4+ u Ce3+ unutar kristalne rešetke bez narušavanja strukture pri čemu nastaju vakancije kisika. Kisikove vakancije mogu se slobodno kretati unutar kristalne rešetke te se na njih mogu lako adsorbirati molekule kisika iz okoline. Smanjenje veličine čestica te dopiranje raznim elementima s nižom valencijom i radijusom dodatno potiče stvaranje vakancija kisika te poboljšava primjenska svojstva cerijevog oksida. Među brojnim metodama sinteze nanomaterijala hidrotermalna metoda ističe se svojom jednostavnošću, ekološkom prihvatljivošću, niskom cijenom te mogućnošću dobivanja produkata visoke čistoće i homogenosti te male veličine čestica. U ovom radu hidrotermalnom metodom pripremljene su nanočestice bakrom dopiranoga cerijeva(IV) oksida (CuxCe1-xO2, x = 0, 0,1, 0,2, 0,3, 0,4 i 0,5), toplinski obrađene i temeljito analizirane različitim metodama karakterizacije nanomaterijala. Katalitička aktivnost pripremljenih nanokatalizatora ispitivana je na procesu oksidacije hlapivih organskih spojeva korištenjem plinovite mješavine benzena, toluena, etilbenzena i o-ksilena (BTEX). Provedena je i kinetička analiza rasta zrna pri izotermnim uvjetima s ciljem utvrđivanja utjecaja dodatka bakra na toplinsku stabilnost cerijeva(IV) oksida. Rendgenskom difrakcijskom analizom (XRD) utvrđeno je da do nominalnog udjela od 40 mol. % Cu ne dolazi do pojave sekundarnih faza. Veličine kristalita uzoraka bez toplinske obrade dosad su nezabilježene za bakrom dopirani cerijev(IV) oksid te iznose ispod 4 nm. Veličine čestica određene transmisijskom elektronskom mikroskopijom (TEM) u suglasju su s vrijednostima dobivenim za veličine kristalita. Masenom spektrometrijom induktivno spregnute plazme (ICP-MS), energijski razlučujućom rendgenskom spektroskopijom (EDS) i rendgenskom fotoelektronskom spektroskopijom (XPS) utvrđeno je da je stvarni udio bakra u uzorcima manji od nominalnog. Međutim, sveukupni rezultati pokazuju kako dodatak bakra ima pozitivan utjecaj na brojna svojstva CeO2, što uključuje smanjenje zabranjene zone, poboljšanje reducibilnosti i toplinske stabilnosti, te povećanje katalitičke aktivnosti. Dobiveni rezultati ukazuju na postojanje snažne interakcije između bakra i CeO2, što bi značilo je došlo do stvaranja čvrste otopine. Među pripremljenim uzorcima posebno se ističe uzorak s nominalnim udjelom bakra od 40 mol. % kao uzorak s najboljom toplinskom stabilnošću u cijelom ispitivanom području (od 300 do 700 °C), najboljom katalitičkom aktivnošću za ispitivane hlapive organske spojeve, te najvećim udjelom vakancija kisika u strukturi. Cerium(IV) oxide (CeO2) is one of the most important lanthanide oxides extensively used in various fields such as polishing, energy production and storage, environmental protection and the most researched catalysis. The key property of CeO2 for catalytic application is the ability of a partial reduction of Ce4+ to Ce3+ within the crystal lattice without the collapse of structure. During this process oxygen vacancies are formed, which can move freely within the crystal lattice and adsorb oxygen molecules from the environment. The reduction of particle size and doping with various elements with lower valence and radius further encourage the creation of oxygen vacancies and improve the properties of cerium oxide. Among many nanomaterial's synthesis methods, the hydrothermal method stands out for its simplicity, environmental friendliness, low cost and the ability to obtain products of high purity and homogeneity, as well as small particle size. In this work, nanoparticles of copper doped cerium(IV) oxide (CuxCe1-xO2, x = 0, 0,1, 0,2, 0,3, 0,4 i 0,5) were prepared by hydrothermal method, thermally treated and thoroughly characterized. The catalytic activity of the prepared nanocatalysts was investigated in the oxidation of volatile organic compounds using a gaseous mixture of benzene, toluene, ethylbenzene and o-xylene (BTEX). An isothermal grain growth kinetics analysis was also performed in order to determine the effect of copper addition on the thermal stability of cerium(IV) oxide. X-ray diffraction analysis (XRD) showed that no secondary phases occur up to the nominal share of 40 mol. % Cu. The crystallite sizes of samples without thermal treatment have not been recorded so far for copper doped cerium oxide and are below 4 nm. Particle sizes determined by transmission electron microscopy (TEM) are in agreement with the values obtained for crystallite sizes. Inductively coupled plasma mass spectrometry (ICP-MS), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) showed that the actual copper content in the samples is lower than nominal. However, the overall results show that the addition of copper has a positive effect on a number of CeO2 properties, which includes the reduction of the band gap, improvement of reducibility and thermal stability, and an increase in catalytic activity. The obtained results indicate the existence of a strong interaction between copper and CeO2, which would mean that a solid solution was formed. Among the prepared samples, the sample with the nominal copper share of 40 mol. % stands out as the sample with the best thermal stability in the studied temperature range (from 300 to 700 °C), the best catalytic activity for the tested volatile organic compounds, and the largest share of oxygen vacancies in the structure.

U ovom radu sintetizirano je 4 fazno čistih čvrstih otopina cerij-cirkonij oksida dopiranih s 10 mol% europija. Dopiranje cirkonija i europija u kristalnu rešetku cerijeva(IV) oksida dovodi do povećanja katalitičke aktivnosti te termičke stablinosti katalizatora. Cerijev dioksid je široko upotrebljivani spoj u raznim katalitičkim reakcijama, između ostalih i fotokatalitičkim reakcijama. Zbog miješanog valentnog stanja (Ce3+/4+), dolazi do brze izmijene elektrona te do zavidnih redoks svojstava, koji se dodatno mogu poboljšati dopiranjem drugih elemenata u kristalnu rešetku, najčešće drugih lantanoida i/ili prijelaznih metala manjeg ionskog radijusa (Zr, Y). Sintetizirani uzorci su okarakterizirani koristeći rentgensku difrakciju na prahu, termogravimetrijsku analizu te IR spektroskopiju, dok je fotokatalitička aktivnost praćena na UV/VIS spektrofotometru s halogenom lampom od 20 W. Fotokatalitička aktivnost je praćena na razgradnju 3 AZO boje, od kojih je primjećena najbolja razgradnja na metil crveno (40% kroz 15 minuta).

Cerium(IV) oxide (CeO2) possesses significant potential as a sunscreen ingredient because it absorbs UV radiation while being relatively transparent to visible light. Furthermore, its photocatalytic activity is lower in comparison to titania and zinc oxide which are the main inorganic UV-blocking filters used in cosmetic industry at the moment. The aim of this work was to incorporate zinc into the ceria crystal lattice in order to obtain the advantages of both compounds in one material and to compare them to commercially available TiO2. Therefore, pure and zinc doped ceria samples were prepared by hydrothermal synthesis and characterized using various characterization techniques: X-ray diffraction, transmission electron microscopy, electron energy loss spectroscopy, and UV-Vis diffuse reflectance spectroscopy. Their catalytic activity was evaluated using the Rancimat test, while cell toxicity was investigated on HaCaT cell line. Fine ceria and doped ceria nanoparticles with particle sizes around 6 nm and band gap values of 3.23 to 3.14 eV were prepared. Both the doped and pure ceria nanoparticles show no difference in cell viability and are biocompatible with human skin, while being catalytically inactive in the fenol oxidation process.

Dijamant dopiran borom (BDD) osim svojih vrhunskih svojstava materijala, nudi elektrokemičaru nekoliko značajnih svojstava čineći ga intrigantnim materijalom za elektrokemijska istraživanja. To uključuje najširi raspon potencijala elektrodnih materijala; niske pozadinske i kapacitivne struje; smanjeno nakupljanje naslaga u usporedbi s drugim elektrodama, sposobnost izdržavanja ekstremnih potencijala, korozivnog i visokog temperaturnog i tlačnog okruženja. Međutim, BDD nije tipičan materijal za elektrodu, to je poluvodič dopiran borom kako bi postigao karakteristike polumetala. Dopiranje borom omogućuje dijamantu da postane p-tipom poluvodiča i koristi se za različita elektroanalitička ispitivanja štetnih tvari kao što su teški metali, herbicidi, pesticidi, farmaceutici, ali i za određivanje različitih proteina. Uskoro možemo očekivati i sve veću primjenu BDD elektrode kao elektrokemijskog senzora. Boron doped diamond (BDD), in addition to its superior material properties, offers several notable attributes to the electrochemist making it an intriguing material for electrochemical research. These include the widest solvent window of all electrode materials; low background and capacitive currents; reduced fouling compared to other electrodes and; the ability to withstand extreme potentials, corrosive and high temperature and pressure environments. However, BDD is not your typical electrode material, it is a semi-conductor doped degenerately with boron to present semi-metallic characteristics. Boron doping allows the diamond to become a p-type semiconductor and is used for various electroanalytical tests of harmful substances such as heavy metals, herbicides, pesticides, pharmaceuticals, but also for the determination of various proteins. We can soon expect the increasing use of the BDD electrode as an electrochemical sensor.

Intrinzično prevodni polimeri (ICP-ji) so organski polimeri, katerih glavna veriga predstavlja konjugiran sistem enojnih in dvojnih kovalentnih vezi. Z dopiranjem ustvarimo v verigi nosilce naboja, tako imenovane solitone, polarone ali bipolarone, kar pomeni, da ICP-ji v dopiranem stanju prevajajo električni tok. Poleg visoke električne prevodnosti v dopiranem stanju, ICP-ji izkazujejo še dobre kapacitivne, optične in fizikalne lastnosti (npr. fleksibilnost). Za izboljšanje njihove stabilnosti, ki predstavlja glavno omejitev uporabe, se navadno pripravljajo nanokompozitni materiali ICP-jev. ICP-ji se uporabljajo v antikorozijskih premazih, senzorjih in zaščitah proti elektromagnetnem sevanju. Pomembno vlogo imajo tudi v medicini, napravah za shranjevanje energije in napredni tehnologiji. Intrinsically conductive polymers (ICPs) are organic polymers with a conjugated system of single and double covalent bonds in their backbone. Process of doping the polymer chain introduces charge carriers, so-called solitons, polarons and bipolarons. This makes ICPs in doped state electrically conductive. In addition to high electrical conductivity in the doped state, ICPs exhibit also good capacitive, optical, and physical (e.g. flexibility) properties. To improve their stability, which is the main limitation of their use, nanocomposite ICP materials are usually prepared. ICPs are used in anti-corrosion coatings, sensors and shielding against electromagnetic radiation. They also play an important role in medicine, energy storage devices and advanced technology.

Hematit (α-Fe2O3) se zbog svojih karakteristika poput male vrijednosti energijskog procijepa (oko 2.1 eV), izuzetne stabilnosti, netoksičnosti i niske cijene, intenzivno istražuje kao fotokatalizator i materijal za izradu fotoanoda. Međutim, njegov veliki nedostatak je loša električna vodljivost koju treba povećati. Jedan od načina je dopiranje, odnosno ugradnja primjesa koje će zamijeniti osnovni atom (Fe3+) na njegovu mjestu u kristalnoj rešetki. U ovom radu metodom elektroispredanja provedena je sinteza 1D hematita u obliku vlakana bez i sa dodatkom 2 at. % i 5 at. % Ru3+ kao ekstrinsične primjese. Kako bi se utvrdio utjecaj Ru3+ dopanda na morfološka, strukturna, optička i poluvodička svojstva hematita, vlakana su karakterizirana sljedećim metodama: UV/Vis, ATR-FTIR, SEM, EDS i XRD. Prema rezultatima svih metoda, vlakna se dominantno sastoje od hematitne faze. Usporedbom ATR-FTIR spektara i difraktograma dopiranih i nedopiranih vlakana vidljiv je pomak vrpci (ATR-FTIR) i pomak maksimuma (XRD), što potvrđuje uspješnu ugradnju Ru3+ iona u strukturu hematita. Utjecaj dopiranja na optička i poluvodička svojstva hematita jasno je vidljiv i u smanjenoj vrijednosti energijskog procijepa dopiranih uzoraka [Ebg (5 at. % Ru3+) = 2,05 eV, direktni prijelaz] u odnosu na nedopirani uzorak (Ebg = 2,10 eV, direktni prijelaz) što ukazuje na povećanje električne vodljivosti dopiranih uzoraka. Materijal ovakvih karakteristika potencijalni je kandidat za primjenu u procesima pročišćavanja otpadnih voda kao fotokatalizator. Hematite (α-Fe2O3) is being intensively investigated for use as a photocatalyst and photoanode material due to its properties such as low energy gap value (about 2.1 eV), exceptional stability, nontoxicity, and low cost. However, its major drawback is poor electrical conductivity, which needs to be enhanced. One of the ways is doping, which is the incorporation of impurities to replace the base atom (Fe3+) in its place in the crystal lattice. In this work, the synthesis of 1D hematite in the form of fibers was carried out by electrospinning method, without and with the addition of 2 at. % and 5 at. % Ru3+ as extrinsic impurities. To determine the effect of Ru3+ doping on the morphological, structural, optical, and semiconducting properties of hematite, the fibers were characterized by the following methods: UV/Vis, ATR-FTIR, SEM, EDS, and XRD. According to the results of all methods, the fibers are predominantly composed of the hematite phase. Comparison of ATR-FTIR spectra and diffractograms of doped and undoped fibers shows a band shift (ATR-FTIR) and a maximum shift (XRD), confirming the successful incorporation of Ru3+ ions into the hematite structure. The influence of doping on the optical and semiconducting properties of hematite is reflected in the reduced value of the energy gap of the doped samples [Ebg (5% at. Ru3+) = 2.05 eV, direct transition] to the undoped sample (Ebg = 2.10 eV, direct transition), indicating an increase in the electrical conductivity of the doped samples. Material with such properties is a potential candidate for application in wastewater treatment processes as a photocatalyst.

Uzorci čistog i dopiranog cerijeva(IV) oksida (CeO2) s 10, 20 i 30% mangana pripravljeni su mehanokemijsokm sintezom i potom ispitivani različitim metodama karakterizacije. Kao prekursori korišteni su cerijev(III) klorid, manganov(II) klorid i natrijev karbonat dok je natrijev klorid korišten kao razrjeđivač koji odvaja čestice produkta te sprječava njihov daljnji rast. Uzorci pripravljeni mehanokemijskom sintezom istraživani su rendgenskom difrakcijom (XRD) te diferencijalnom toplinskom i termogravimetrijskom analizom (DTA/TGA). Nakon sinteze uzorci su termički obrađeni na 500 °C u trajanju 2 sata kako bi se iz produkata sinteze dobio CeO2. Obrađeni uzorci podvrgnuti su rendgenskoj difrakcijskoj analizi (XRD), infracrvenoj spektroskopiji s Fourierovom transformacijom (FTIR) i pretražnoj elektronskoj mikroskopiji (SEM). Katalitička aktivnost dobivenih uzoraka ispitana je na procesu oksidacije toluena u integriranom reaktoru s nepokretnim slojem katalizatora, a za detekciju toluena nakon oksidacije korištena je plinska kromatografija (GC).Rezultati su pokazali da mehanokemijskom sintezom, u sintezama s manganom, iz korištenih prekursora uz cerijev(IV) oksid nastaje i birnesit kao sekundarna kristalna faza. Dopiranje manganom dovodi do smanjenja veličine kristalita CeO2, ali ne dovodi do značajnih promjena u morfologiji kao ni katalitičkoj aktivnosti CeO2. Pure ceria samples as well as 10, 20 and 30% manganese doped CeO2 were prepared via mechanochemical synthesis. The as-prepared samples were characterized using X-ray diffraction (XRD) and differential thermal and thermo-gravimetric analysis (DTA-TGA). After mechanochemical synthesis, samples were thermally treated at 500 °C for 2 h, to enable the transformation of synthesis products to CeO2. The thermally treated samples were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Catalytic activity was tested on toluene oxidation process in an integral up-flow fixed bed reactor and for the detection of residual toluene after oxidation, gas chromatography (GC) was used. During mechanochemical synthesis of doped samples with the used precursors the formation of ceria occurs, along with birnessite as a secondary crystal phase. Doping with manganese caused a decrease in crystallite size. However, no significant differences in morphology or catalytic activity of CeO2 were observed.

V pričujočem delu smo se ukvarjali z razvojem novega tipa senzorskega elementa, ki temelji na 2,5 dimenzionalnem elektronskem plinu. Želeli smo določiti vzrok za nepravilno delovanje že izdelanih elementov, zasnovati novo verzijo polprevodniške heterostrukture in zanjo definirati vse procesne korake. Obstoječe elemente smo karakterizirali in z uporabo računalniških simulacij ugotovili vzrok za nepravilno delovanje. Na podlagi že poznanih elementov in literature s tega področja smo predlagali nov tip strukture, za katerega smo s pomočjo simulacij definirali proces izdelave. Preučili smo vplive parametrov ionske implantacije, jedkanja, geometrije in ohmskih kontaktov na delovanje elementa. Preverili smo delovanje končne strukture in določili optimalne obratovalne pogoje, pri katerih so dosežene željene specifikacije elementa. Rezultati nam dajejo vpogled v delovanje končnega elementa in v zahtevnost procesa izdelave. Opravljeno delo služi kot osnova za izdelavo nove iteracije vzorcev. The present text describes our development of a new type of sensor element based on 2.5 dimensional electron gas. We wanted to find the reason for incorrect functioning of previously manufactured elements, then further, to design a new version of semiconductor heterostructure, and to define all the process steps needed for its manufacture. We have characterized the existing samples, and by means of computer simulations, we have determined the reasons for their previous incorrect functioning. Based on the present knowledge and literature from the field, we have suggested a new type of structure for which we have also defined the manufacturing process based on computer simulations. We have studied the impact of ion implantation, etching, geometry and ohmic contacts on functionality of the device. We have tested the functionality of the final structure and determined the optimal operational conditions at which the desired specifications are reached. The obtained results give us insight into functioning of the final device, and into the feasibility of its manufacturing process. This work is used as the basis for manufacturing of a new iteration of samples.

U okviru ovog rada pripravljen je kobaltom dopiran ganit. Prikladna spinelna struktura ganita omogućila je dopiranje, odnosno uklapanje kobalta kao strane ionske vrste u kristalnu rešetku ganita, u širokom području sastava, s ciljem priprave različitih pigmenata. Ganit je kao pigment osobito prikladan na temelju netoksičnosti i velike termičke i kemijske stabilnosti. Dopiranjem već i vrlo male količine kobalta u strukturu ganita mogu se dobiti estetski ugodne i intenzivne boje. Uzorci su pripravljeni sol-gel tehnikom, a karakterizacija je provedena primjerenim klasičnim metodama karakterizacije; rendgenskom difrakcijskom analizom, DRS-UV-VIS spektroskopijom te ATR–FTIR-om. Rezultati dobro opisuju sustav, ali iz istih nije moguće u potpunosti razlučiti utjecaj dopiranja, tj. utjecaj promjene strukturnih svojstava na razvoj boje. Stoga je osmišljena i provedena korelacija DRS-UV-VIS i ATR-FTIR spektroskopija. Pomoću programa MATLAB, koristeći specifične algoritme, dobiveni su sinkroni i asinkroni 2D korelacijski spektri i oni nam daju više informacija od prethodno dobivenih diskretnih spektara. The aim of this study was to prepare cobalt-doped gahnite. The suitable spinel structure of gahnite enabled the doping by foreign ions into its lattice, over a wide range of compositions, in order to prepare different pigments. Gahnite is particularly suitable for a pigment because it is non-toxic and shows great thermal and chemical stability. By doping a very small amount of cobalt in the structure of the gahnite, aesthetically pleasing and intense colours can be obtained. Samples were prepared by sol-gel technique, characterization was performed using classical characterization methods; X-ray diffraction analysis, DRS-UV-VIS and by ATR-FTIR spectroscopy. The results describe the system well, but it is not possible to completely resolve the influence of doping, i.e. the influence of changes in structural properties on colour development. Therefore, the correlation procedure of DRS-UV-VIS and ATR-FTIR spectroscopy results was designed and performed. Using the MATLAB program, using specific algorithms, synchronous and asynchronous 2D correlation spectra were obtained and they provide more information than the previously obtained discrete spectra.

Cilj ove doktorske disertacije je bio da se analizira i sagleda uticaj mehaničke aktivacije na strukturu i svojstva nedopiranog i dopiranog SrTiO3 praha, kao i uticaj na strukturu i svojstva keramike dobijene sinterovanjem ispresaka pomenutih prahova. U slučaju sinterovanih nedopiranih SrTiO3 uzoraka dodatno su razmatrane promene u brzini densifikacije i kinetici sinterovanja. Uticaj mehaničke aktivacije i dopanta na električna svojstva stroncijum-titanatne keramike je analiziran merenjem frekventne zavisnosti relativne dielektrične permitivnosti i tangensa ugla dielektričnih gubitaka na sobnoj temperaturi. Magnetnim merenjima, kod dopiranih SrTiO3 uzoraka dobijenih dodavanjem mangan(IV)-oksida, praćen je uticaj mehaničke aktivacije, koncentracije dopanta i jačine magnetnog polja na vrednost specifične magnetizacije. Mehanička aktivacija SrTiO3 praha je vršena u visoko-energetskom planetarnom mlinu sa kuglama, pri čemu je vreme aktivacije nedopiranog praha iznosilo: 5, 10, 30, 60, 90 i 120 minuta, dok je efekat dopiranja razmatran za aktivaciju od 10, 30 i 120 minuta. U cilju dobijanja SrTiO3:Mn sistema, tipa Sr1-xMnxTiO3 (SMnT) ili SrTi1-xMnxO3 (STMn), u polazni SrTiO3 prah je dodat mangan(IV)-oksid (MnO2), pri čemu su izabrane vrednosti za x bile: 0,03, 0,06 i 0,12. Raspodela veličina čestica je ukazala da je mehanička aktivacija dovela do usitnjavanja čestica polaznog praha, uz istovremenu pojavu šire raspodele veličina čestica pri dužim vremenima aktivacije. Skenirajućom i transmisionom elektronskom mikroskopijom (SEM i TEM) analizirana je mikrostruktura i morfologija polaznog i mehanički aktiviranih prahova. BET metodom je utvrđeno da se najviša vrednost specifične površine kod nedopiranih prahova postiže pri aktivaciji u trajanju od 60 minuta, dok pri daljoj aktivaciji specifična površina ostaje približno konstantne vrednosti, usled povećane sekundarne aglomerizacije. Pokazano je da je gustina ispreska kod praha aktiviranog tokom 10-30 minuta najveća. Zapaženo je sniženje intenziteta XRD pikova sa porastom vremena aktivacije, kao i širenje difrakcionih linija, usled smanjenja veličine kristalita i porasta mikronaprezanja. Primenjena mehanička aktivacija je omogućila formiranje kubnog nanokristalnog SrTiO3 praha, pri čemu veličina kristalita opada i do ~20 nm sa uvećanjem vremena aktivacije. Uočena promena u vrednosti parametra kristalne rešetke a je posredno ukazala i na moguće promene u koncentraciji kiseonikovih vakancija. Analizom Ramanovih spektara je praćen uticaj mehaničke aktivacije na promene u fononskom spektru prahova, sa posebnim akcentom na polarne TO mode, čiji oblik i intenzitet bitno zavise od defekata kao što su kiseonikove vakancije. Analiza optičkih svojstava kristalnih materijala pomoću UV-Vis spektroskopije je ukazala na sniženje energije zabranjene zone sa uvećanjem vremena aktivacije. Primenom dilatometrije je ispitivan uticaj mehaničke aktivacije na početni stadijum sinterovanja dvostrano presovanih SrTiO3 prahova. Uočeno je značajno smanjenje temperature početka skupljanja ispreska, kao i uticaj na brzinu skupljanja i na konačne gustine sinterovanih uzoraka. Primena Dornove metode je ukazala na značajno smanjenje efektivne energije aktivacije transporta mase u početnom stadijumu sinterovanja, sa porastom vremena mehaničke aktivacije polaznog praha. Za uzorke dobijene sinterovanjem do 1300 oC, uz izotermsko zadržavanje na maksimalnoj temperaturi u trajanju od 2h, je izvršena korelacija između zapaženih strukturnih promena i promena u dielektričnim svojstvima, nastalim usled mehaničke aktivacije. Posebna pažnja je posvećena uticaju promena: gustine, poroznosti, veličine zrna i kristalita, kao i uticaju promena parametra kristalne rešetke, na dielektrična svojstva. Promene vrednosti relativne dielektrične permitivnosti su razmatrane i sa stanovišta promena u oblasti granice zrna, posebno imajući u vidu rezultate koji su ukazali na promenu koncentracije kiseonikovih vakancija... The aim of this doctoral dissertation is to analyze and evaluate the effect of mechanical activation on the structure and properties of undoped and doped SrTiO3 powders, as well as the effect on the structure and properties of the ceramics obtained by sintering these powders. For the sintered undoped SrTiO3 samples, changes in the densification rate were also analyzed. The effect of mechanical activation and dopant on the electrical properties of strontium titanate ceramics was analyzed by measuring the frequency-dependent relative dielectric permittivity and the loss tangent at room temperature. Magnetic measurements performed on the doped SrTiO3 samples obtained by the addition of manganese(IV) oxide were used to monitor the influence of mechanical activation, dopant concentration and magnetic field strength on magnetization. The mechanical activation of the SrTiO3 powder was performed in a high-energy planetary ball mill; the activation times of the undoped powder were: 5, 10, 30, 60, 90, and 120 minutes, while the doping effect was analyzed for the activation periods of 10, 30, and 120 minutes. In order to obtain SrTiO3:Mn systems belonging to Sr1-xMnxTiO3 (SMnT) or SrTi1-xMnxO3 (STMn) compound types, manganese(IV) oxide (MnO2) was added to the starting SrTiO3 powder, where the values selected for x were: 0.03, 0.06 and 0.12. The particle size distribution indicated that mechanical activation resulted in the comminution of the starting powder particles, accompanied with a wider particle size distribution at longer activation times. The microstructural and morphological analysis of the starting and mechanically activated powders was performed using scanning and transmission electron microscopy (SEM and TEM). The BET method revealed that 60-minute activation resulted in the highest specific surface area in undoped powders, while further activation led to a relatively constant specific surface due to increased secondary agglomeration. The density of the powder activated for 10-30 minutes was the highest. The intensity of XRD peaks decreased with longer activation times and diffraction lines broadened due to decreased crystallite sizes and increased microstrain. Mechanical activation led to the formation of cubic nanocrystalline SrTiO3 powder, with the minimum crystallite size of 20 nm. The observed change in the value of the crystal lattice parameter indirectly indicated possible changes in the concentration of oxygen vacancies. The analysis of Raman spectra revealed the effect of mechanical activation on the phonon spectrum of powders, with particular emphasis on polar TO modes which shape and intensity generally depend on defects such as oxygen vacancies. The analysis of the optical properties of crystalline materials by UV-Vis spectroscopy indicated a correlation between decreased band gap energy and increased activation times. The effect of mechanical activation on the initial stage of sintering of bilaterally pressed SrTiO3 powders was investigated by dilatometry. A significant decrease in the temperature of the onset of densification was observed, as well as the effect of mechanical activation on the densification rate and on the final density of the sintered samples. The application of the Dorn method indicated a significant decrease in the effective activation energy of mass transport in the initial sintering stage, with a longer time of the mechanical activation of the starting powder. For the samples obtained by sintering up to 1300 °C, with isothermal retention at the maximum temperature for 2 h, a correlation between the structural changes and the changes in dielectric properties resulting from mechanical activation was observed. Particular attention was paid to the effect of changes: density, porosity, grain and crystallite size, as well as the effect of crystal lattice parameter changes on the dielectric properties. The changed values of the relative dielectric permittivity were analyzed in the context of the changes in the grainboundary region, with special respect to the results indicating changes in the oxygen vacancy concentration.

Znanstvena istraživanja u sklopu inženjerstva koštanog tkiva usmjerena su ka istraživanju materijala za koštane usadke koji oponašaju prirodno koštano tkivo. Kako bi materijal bio odgovarajući mora zadovoljavati tražena svojstva, od mehaničkih do bioloških, kemijskih i fizikalnih. Kao visokopotencijalni materijal pokazao se hidroksiapatit, koji zadovoljava uvjete poput biokompatibilnosti, bioaktivnosti, osteoinduktivnosti, biorazgradnje i sl., te je strukturno i kemijski sličan biološkom apatitu koji se nalazi u prirodnom koštanom tkivu. Cilj ovog istraživanja je strukturna karakterizacija sintetizitanog hidroksiapatita iz biogenog izvora supstituiranog stroncijem (0, 1, 5 and 10 mol%), koji ima važnu ulogu u razvoju koštanog tkiva i koristi se za tretiranje bolesti koštanog sustava. Sinteza iz biogenog izvora omogućuje da produkt bude nestehiometrijski hidroksiapatit, koji pokazuje više sličnosti biološkom apatitu. Osim toga, sadrži brojne ione važne za razvoj koštanog tkiva. Dobiveni uzorci prije i nakon toplinske obrade analizirani su rendgenskom difrakcijskom analizom (XRD) i Rietveldovom metodom utočnjavanja pomoću računalnog programa DIFFRAC.SUITE TOPAS V.5.0. Pripremljeni kalcijevi fosfati (CaP) sastoje se od hidroksiapatita (HAp), oktakalcijevog fosfata pentahidrata (OCP) i amorfnog kalcijevog fosfata (ACP), a toplinski obrađeni uzorci od β-trikalcijevog fosfata (β-TCP) i ACP-a. Povećanjem udjela stroncija dolazi do povećanja parametara jedinične ćelije dobivenih CaP zbog supstitucije ionom većeg ionskog radijusa. Stroncij u HAp-u zauzima Ca1 položaj, u OCP-u Ca3, Ca4, Ca7 i Ca8, dok u β-TCP-u Ca1, Ca2, Ca3 i Ca4 položaje. The main goal of scientific researches in the field of bone tissue engineering is to synthetize a material that mimics natural bony tissue, in order to use it as a bone implant. The material has to be chemically and structurally similar to bony tissue, and possess required properties, such as biocompatibility, bioactivity, osteoinductivity, biodegradibility and mechanical support. Hydroxyapatite (HAp) has shown all of the above mentioned properties and is very similar to biological apatite, that is present in natural bony tissue. Therefore, the aim of this research is a structural characterization of synthetized HAp obtained from biogenic source, along with strontium substitution (0, 1, 5 and 10 mol%), that is crucial for bone growth and is used for treating osteoporosis and similar diseases. Result of using biogenic source is multi-substituted nonstochiometric HAp, which is more similar to biological apatite than synthetic HAp. Various trace elements present in HAp obtained from biogenic source are crucial for bone growth. Prepared samples were analysed by X-ray diffraction analysis (XRD), in order to determine their phase composition. Obtained results were additionally processed by Rietveld refinement method using software, DIFFRAC.SUITE TOPAS V.5.0. To determine thermal stability of samples, they were heat-treated at 1200 °C and analysed by X-ray diffraction and using Rietveld refinement method. Prepared calcium phosphates were composed of hydroxyapatite (HAp), octacalcium phosphate pentahydrate (OCP) and amorphous calcium phosphate (ACP), while heat-treated samples were composed of β-tricalcium phosophate (β-TCP) and amorphous calcium phosphate (ACP). Along with increase of Sr-substitution level, lattice parameters of obtained CaPs increased, as a result of larger radius of substitued strontium ion. Strontium ion occupies in hydroxyapatite Ca1 site, in OCP sites Ca3, Ca4, Ca7 and Ca8, while in β-TCP it occupies sites Ca1, Ca2, Ca3 and Ca4.

Cinkov oksid (ZnO) jedan je od najznačajnijih spojeva cinka, poluvodič koji svoju primjenu nalazi u raznim granama industrije zbog dobrih električnih i mehaničkih svojstava te termičke stabilnosti. Primjenu ZnO kao fotokatalizatora otežava velika energija zabranjene zone (3, 7 eV) i brza rekombinacija elektrona i šupljina. Dodatkom dopanata može se smanjiti energija zabranjene zone cinkova oksida i ograničiti proces rekombinacije te tako povećati njegova fotokatalitička aktivnost. Jedan od dopanata koji se u tu svrhu koristi je kadmij. ZnO dopiran kadmijem moguće je pripraviti različitim metodama poput sinteze sagorijevanjem, termolize, koprecipitacije, sonokemijske sinteze, hidrotermalne sinteze, sol‐gel procesa itd. Neke od navedenih metoda su kompleksne, teško ih je kontrolirati, zahtijevaju skupu opremu ili prekursore, neprikladne su za sintezu nanočestica ili dovode do visokog stupnja aglomeracije produkta. Mehanokemijska sinteza je jednostavna, ekološki i ekonomski prihvatljiva metoda dobivanja nanočestica koja omogućava dobivanje velike količine produkta.U ovom radu mehanokemijskom sintezom pripravljene su nanočestice cinkova oksida dopiranoga kadmijem u različitim udjelima. Kao prekursori korišteni su ZnCl2, CdCl2 i Na2CO2, dok je NaCl upotrijebljen kao razrjeđivač. Uzorci su termički obrađeni pri 600 °C u trajanju od 2 sata, isprani, te analizirani rendgenskom difrakcijom praha (XRD), infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR), UV‐Vis difuznom refleksijskom spektroskopijom (DRS), elektronskim pretražnim mikroskopom (SEM), energetski razlučujućom rendgenskom spektroskopijom (EDS) i adsorpcijom N2. Fotokatalitička aktivnost pripremljenih katalizatora vrednovana je u procesu razgradnje metilenskog plavila. Utvrđeno je da je mehanokemijskom sintezom moguće ugraditi do 2 mol. % kadmija u kristalnu rešetku cinkova oksida, dok veći udjeli rezultiraju pojavom drugih faza poput kadmijeva oksida i kadmijeva karbonata. Dopiranje utječe na povećanje kristalita ZnO, no veće promjene u morfologiji, energiji zabranjene zone, a sukladno tome i fotokatalitičkoj aktivnosti ZnO nisu uočene.

Vanadijev dioksid (VO2) je termokromni materijal u kojem pri 68 °C dolazi do reverzibilne fazne transformacije iz niskotemperaturne, monoklinske, poluvodičke faze koja je propusna za infra-crveno (IC) zračenje u visokotemperaturnu, rutilnu, metalnu fazu koja IC zračenje reflektira. Ova transformacija čini VO2 materijalom prikladnim za izradu pametnih prozora, čija je funkcija pri visokim temperaturama okoliša spriječiti prolaz dijela IC zračenja u objekt, pri čemu nije onemogućen prolaz vidljivog zračenja, odnosno svjetla. Iako VO2 ima brojne prednosti u odnosu na druge anorganske i organske termokromne materijale, ima i ozbiljne nedostatke. Osnovni nedostaci VO2 su visoka temperatura fazne transformacije, Tc, mala propusnost za vidljivo svjetlo (mali omjer propuštenog i upadnog svjetla), Tlum, zbog čega sloj VO2 na staklu mora biti vrlo tanak, ograničena sposobnost modulacije (mala razlika u propusnosti ukupnog sunčeva zračenja metalne i poluvodičke faze), ΔTsol, te neprivlačna žućkasta boja. Stoga se VO2, modificira dopiranjem s Zr kako bi se smanjili navedeni nedostatci. Dopiranje sa Zr smatra se najkorisnijim za unaprjeđenje svih navedenih svojstava budući da razlika u radijusu V4+ i Zr4+ destabilizira monoklinski VO2, što dovodi do sniženja Tc. Dopiranje sa Zr proširuje zabranjenu zonu VO2 što može dovesti do porasta Tlum i ΔTsol, a Zr modificira i boju VO2. Dopirani VO2 pripravlja se nizom tehnika poput kemijskog nanošenja iz plinovite faze, magnetronskog rasprašivanja ili sol-gel sinteze. Poznata metoda za pripravu VO2, sinteza preko vanadil glikolata, VO(OCH2CH2O), nije do sada korištena za pripravu Zr dopiranog VO2. Stoga je u ovom radu prvo iz amonijeva metavanadata, NH4VO3, etilenglikola, C2H6O2, i cirkonijeva butoksida, Zr(OC4H9)4, prvo pripravljen prekursor iz kojeg se termičkom obradom može dobiti VO2. Pripravljeni su uzorci ciljane stehiometrije V1-xZrxO2, gdje je x=0; 0,02; 0,04 i 0,06 te je promatran utjecaj Zr na tijek termičke evolucije vanadijevih oksida. Korištene su metode diferencijalne termičke i termo-gravimetrijske analize (DTA/TGA), rendgenske difrakcije (XRD), infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i pretražne elektronske mikroskopije (SEM). Utvrđeno je da udio Zr značajno utječe na fazni sastav i morfologiju prekursora, u kojem s porastom udjela Zr ima sve više amorfne faze. Nadalje, utvrđeno je da zagrijavanjem prekursora dolazi do kristalizacije različitih vanadijevih okisda poput VO2, V3O7, V2O5 te cirkonijeva vanadata, Zr(V2O7). Zapaženo je da udio Zr utječe na tijek kristalizacije i veličinu kristalita VO2. Također je utvrđen termički režim pri kojem se u uzorcima bez ili s malim udjelom Zr može u potpunosti ili gotovo u potpunosti izbjeći kristalizacija svih faza osim VO2. Međutim, analize ukazuju da opisanim načinom priprave nije došlo do ugradnje Zr u kristalnu rešetku VO2. Vanadium dioxide (VO2) is a thermochromic material in which at 68 °C a reversible phase transformation occurs from a low temperature, monoclinic, semiconductor phase permeable to infrared (IC) radiation to a high-temperature, rutile, metal phase that reflects IC radiation. This transformation makes VO2 a suitable material for making smart windows, whose function is to prevent the passage of a part of IC radiation to an object at high ambient temperatures, without preventing the passage of visible light. Although VO2 has many advantages over other inorganic and organic thermochromic materials, there are serious drawbacks. The basic flaws of VO2 are high phase transformation temperature, Tc, low bandwidth for visible light (low ratio of transmitted and incident light), Tlum, which is why the layer of VO2 on the glass has to be very thin, the limited modulation ability (small difference in permeability of total solar radiation of metal and semiconductor phases), ΔTsol, and unattractive yellowish color. Therefore, VO2 is modified by doping with Zr to reduce these defects. Doping with Zr is considered to be most useful for improving all of the above mentioned properties since the difference in the radius of V4+ and Zr4+ destabilizes the monoclinic VO2, leading to a decrease in Tc. Doping with Zr widens the VO2 band-gap, which can lead to a rise in Tlum and ΔTsol, and Zr also modifies the VO2 color. The doped VO2 could be prepared by a series of techniques such as chemical deposition from a gas phase, magnetron sputtering or sol-gel synthesis. Although it is a known method for the preparation of VO2, the synthesis through vanadyl glycolate, VO(OCH2CH2O), has not been used up to date for the preparation of Zr doped VO2. Therefore, in this work, first from the ammonia metavanadate, NH4VO3, ethylene glycol C2H6O2, and zirconium butoxide, Zr(OC4H9)4, a precursor was prepared from which VO2 can be obtained by thermal treatment. Samples of targeted stoichiometry V1-xZrxO2 were prepared, where x = 0; 0.02; 0.04 and 0.06 and the influence of Zr on the course of thermal evolution of vanadium oxide was observed. The methods of differential thermal and thermogravimetric analysis (DTA / TGA), X-ray diffraction (XRD), Fourier transform (FTIR) infrared spectroscopy and scanning electron microscopy (SEM) were used. It was found that Zr significantly influences the phase composition and morphology of the precursor, and that with the increase of the Zr share the quantity of the amorphous phase increases. Furthermore, it has been found that by thermal treatment of the precursor, crystallization of various vanadium phases such as VO2, V3O7, V2O5 and zirconium vanadate, Zr(V2O7) occurs. It has been noted that the Zr share influences the course of crystallization and the size of the crystalline VO2. A thermal regime was also established by which in the samples without or with a small Zr content, the crystallization of all phases except VO2 can completely or almost completely be avoided. However, the analyzes indicate that the described method of preparation did not result in the incorporation of Zr into the crystal lattice of VO2.

Istraživanja u okviru ove doktorske disertacije obuhvatila su sintezu i karakterizaciju monokrista bizmuta i telura dopiranih selenom, cirkonijumom i arsenom dobijenih Čohralski i Bridžman postupkom. Jedinjenja na bazi bizmut telurida predstavljaju vrlo važne materijale za proizvodnju termoelektričnih hladnjaka i uređaja za proizvodnju električne energije. Za karakterizaciju monokristala korišćeno je više savremenih, standardizovanih, visoko rezolutivnih metoda i analitičkih tehnika. Rezultati prve serije eksperimenata pokazuju sintezu i eksperimentalna ispitivanja poluprovodnika n tipa Bi2Te2.88Se0.12 dobijenog metodom Čohralskog. Praćenje strukturnih promena uzoraka vršeno je elektronskim mikroskopom. Elementarni sastav i empirijska formula jedinjenja određeni su pomoću energetsko disperzivne spektrometrije (EDS). Ponašanje uzorka prilikom zagrevanja ispitano je korišćenjem diferencijalne termijske analize (DTA). Fizičke i hemijske osobine materijala su praćene u funkciji povećanja temperature termogravimetrijskom analizom (TGA). Rendgenskom difrakcijom (XRD) dobijeni su podaci položaja difrakcionih maksimuma 2θ (º), vrednosti međupljosnih rastojanja dhkl (Å) za sve refleksije, kao i odgovarajući relativni intenziteti I/Imax koji su dati grafički i tabelarno. Na osnovu dobijenih vrednosti I/Imax i dhkl i upoređivanjem sa literaturnim podacima i JCPDS i ICSD standardima, identifikovano je da je dobijen monokristal i proračunati su parametri jediničnih ćelija poluprovodnika. Vrednosti parametara rešetke dobijene difrakcionom analizom praha Bi2Te2.88Se0.12 veoma su slične konstatama rešetke Bi2Te3, što ukazuje na to da je mali deo telura zamenjen selenom. Vrednosti Vikersove mikrotvrdoće su u opsegu između HV 187 i HV 39.02 i smanjuju se sa povećanjem opterećenja. Pokazalo se da vrlo složen proces infracrvene termografije može biti primenjen za karakterizaciju termoelektričnih elemenata i modula. Rezultati završne serije eksperimenata pokazuju sintezu monokristalnih ingota, BiSbTeSe dopiranog cirkonijumom i BiTeSe dopiranog arsenom, sintetisanih Bridžman metodom. Za utvrđivanje hemijskog sastava proučavanih uzoraka, kao i provere i potvrđivanje homogenosti uzoraka korišćena je analiza energetsko disperzivne spektrometrije (EDS). Merenja rentgenske difrakcije (XRD) pokazala su da dobijeni kristalni ingoti predstavljaju monokristal i potvrđuju jedinjenje Bi2Te3 tipa. Određena je orjentacija (00l) monokristala dopiranog cirkonijumom. Tačka topljenja monokristala dopiranog cirkonijumom određena je dilatometrijskom analizom... Researches in this doctoral dissertation included synthesis and characterization of bismuth telluride single crystals doped with selenium, zirconium and arsenic obtained using Czochralski and Bridgman method. Compounds based on bismuth telluride are very important materials for thermoelectric refrigerators and devices for electricity production. For the characterization of monocrystals, many modern, standardized, high resolution methods and analytical techniques were used. The results of the first series of experiments show synthesis and experimental investigation of the n type Bi2Te2.88Se0.12 semiconductor obtained by the Czochralski method. Monitoring of structure changes of the samples was carried out by electron microscope. The elemental composition and empirical formula of the compound were obtained by energy dispersive spectrometry (EDS) analysis. The behavior of sample upon heating was studied using differential thermal analysis (DTA) technique. Changes in physical and chemical properties of materials were measured as a function of increasing temperature by thermogravimetric analysis (TGA). Data of diffraction peaks 2θ (º) positions, values of interplaned hkl (Å) for all reflections, as well as corresponding relative intensities I/Imax, which are given graphically and in table form, were obtained by X-ray diffraction. Based on the obtained values of I/Imax and dhkl and comparing with the literature data and with JCPDS and ICSD standards, it has been identified that a single crystal has been obtained and the parameters of the semiconductor unit cells were calculated. The lattice parameters values obtained by X-ray diffraction analyses of Bi2Te2.88Se0.12 powder are very similar to Bi2Te3 lattice constants, indicating that a small portion of tellurium was replaced with selenium. The Vickers microhardness values are in range between HV 187 and HV 39.02 and decrease with load increasing. It has been shown that very complex process of infrared thermography can be applied for characterization of thermoelectric elements and modules. The results of the final series of experiments show the synthesis of monocrystal ingots, BiSbTeSe doped with zirconium and BiTeSe doped with arsenic, synthesized by the Bridgman method. An analysis of energy dispersive spectrometry (EDS) was used to determine the chemical composition of the samples studied, as well as checking and confirming the homogeneity of the samples. Measurements of X-ray diffraction (XRD) showed that the resulting crystalline ingots represent a single crystal and confirm the compound of Bi2Te3 type. The orientation (00l) of monocrystal doped with zirconium was determined. The melting point of monocrystal doped with zirconium was determined by dilatometric analysis. Mobility, concentration, resistivity/conductivity, of majority of charge bearers and Hall coefficient of single crystals, of BiSbTeSe doped with Zr and BiTeSe doped with arsenic, were determined using a Hall Effect measurement system based on the Van der Pauw method. From different parts of BiSbTeSe single crystal ingot doped with zirconium, samples were cut and cleaved normally and parallel to the crystallization direction...

Cilj ovog rada bio je istražiti kinetiku rasta nanokristalnog cerijevog (IV) oksida (CeO2) te utjecaj dopiranja bakrom na kinetiku rasta. Čvrsta otopina cerijevog oksida i 10 mol. % bakra dobivena je hidrotermalnom sintezom te je termički obrađivana na različitim temperaturama i vremenima obrade. Neobrađeni uzorak i obrađeni uzorci analizirani su rendgenskom difrakcijskom analizom praha te je na temelju dobivenih difraktograma pomoću Scherrerove jednadžbe izračunavana veličina kristalita. Na temelju dobivenih veličina kristalita određeni su kinetički parametri rasta i doneseni zaključci o utjecaju dopiranja bakrom na stabilnost cerijevog oksida. The aim of this research was to determine the growth kinetics of nanocrystalline cerium (IV) oxide (CeO2, ceria) and the influence of copper doping on the growth kinetics. Solid solution of ceria and 10 mol.% of copper was prepared by hydrothermal synthesis and further thermally processed at different temperatures and various durations. The samples were then analysed by X-ray diffraction. Using the Scherrer equation, the crystal size was calculated from the obtained diffractograms. Based on the crystallite sizes, the conclusions about the influence of copper doping on kinetic parameters of growth and stability of the ceria can be derived.

U ovom radu prikazano je istraživanje utjecaja dopanata, samarija i neodimija, na strukturu i svojstva TiO2. Istraživanje je provedeno prvenstveno za primjenu prevlaka TiO2 u bojom senzibiliziranim solarnim ćelijama (DSSC). TiO2 je poluvodič širokog energijskog procjepa, a njegova fizikalno-kemijska svojstva čine ga pogodnim za vodljivi sloj radne elektrode u DSSC. Dopiranjem ionima rijetkih zemalja dodatne razine unutar energijskog procjepa dozvoljavaju TiO2 da sudjeluje i kao aktivan sloj u radu DSSC. Daljnje modificiranje dopiranog TiO2 organskim molekulama dodatno povećava apsorpciju u vidljivom dijelu spektra. Modificiranje utječe na topografiju i morfologiju prevlaka, a posljedično i na njihova svojstva. Elektronskom mikroskopijom i UV/Vis i Ramanovom spektroskopijom okarakterizirani su nanoprahovi i prevlake dopiranog TiO2 i dopiranog pa naknadno modificiranog TiO2. Rezultati UV/Vis spektroskopije ukazuju na to da će u DSSC biti aktivnije prevlake veće specifične površine i prevlake s manje aglomerata, a najaktivniji bi trebao biti TiO2 dopiran samarijem i modificiran salicilnom kiselinom. Najmanje aktivan biti će TiO2 dopiran samarijem i modificiran 5-aminosalicilnom kiselinom. This bachelor’s thesis presents a study of the effects of dopants, samarium and neodymium, on the structure and properties of TiO2. This research focuses primarily on the application of TiO2 coatings in dye-sensitized solar cells (DSSC). TiO2 is a wide band gap semiconductor with physical and chemical properties suitable for application as a conductive layer of the working electrode in DSSC. By doping with rare earth ions additional energy levels in a band gap are added which allow TiO2 to participate as an active layer of DSSC as well as the conductive one. Further modification of rare-earth doped TiO2 with organic molecules increases the absorption in the visible part of the spectrum. Modification affects coatings topography and morphology, and consequently their properties. Electron microscopy and UV/Vis and Raman spectroscopy are used to characterize nanopowders and coatings of rare-earth doped TiO2 and doped TiO2 modified with organic molecules. The results showed that the coatings with larger specific area and lower degree of agglomeration should have greater activity. The most active should be TiO2 doped with samarium and modified with salicylic acid. The least active should be TiO2 doped with samarium and modified with 5-aminosalicylic acid.

Kosti svih kralježnjaka su prirodni kompozitni materijali, građeni od karbonatnog hidroksiapatita koji zauzima 65 % ukupne koštane mase, a ostatak mase su organske tvari i voda. U prirodni karbonatni hidroksiapatit ugrađeni su mnogobrojni metalni ioni u različitim masenim postotcima. Mnoga istraživanja usmjerena su na dopiranje hidroksiapatita cinkovim, stroncijevim i magnezijevim ionima u svrhu povećanja osteogenih svojstava umjetno dobivenih materijala za primjene u inženjerstvu koštanog tkiva. U ovom radu objašnjena je važnost sinteze metalnim ionima dopiranog hidroksiapatita za primjene u inženjerstvu koštanog tkiva. Objašnjena su svojstva, kristalna struktura, način sinteze, uloga u organizmu te mehanizam supstitucije hidroksiapatita cinkovim, stroncijevim i magnezijevim ionima. The bones of all vertebrates are natural composite materials, where one of the components is carbonate hydroxyapatite. Carbonate hydroxyapatite amounts to 65 % of total bone mass, with the remaining mass formed by organic matter and water. Natural carbonate hydroxyapatite is doped with different metal ions at different mass percentages. Many studies have been focused on doping hydroxyapatite with zinc, strontium and magnesium ions to increase osteogenic properties of artificially made materials for the applications in bone tissue engineering. This paper explains crystal lattice of hydroxyapatite, synthesis method, biological role and the mechanism of hydroxyapatite doped with zinc, strontium and magnesium ions. Additionally, explains the importance of the doped hydroxyapatite synthesis for bone tissue engineering.

Istraživanja provedena u ovom radu bila su usmjerena na studij morfoloških, strukturnih, optičkih i poluvodičkih karakteristika čestica ZnO. Studiran je utjecaj procesa dopiranja – ugradnje kationa prijelaznog metala (Fe3+ iona) na navedene karakteristike ZnO. Dopirane čestice ZnO sintetizirane su pri atomskim udjelima Fe3+ iona od 0,5; 1 i 5 %. Hidrotermički postupak odabran je kao jednostavan, reproducibilan i ekološki prihvatljiv postupak sinteze čestica ZnO u dva različita lužnata medija, NH4OH i NaOH. Karakterizacija uzoraka provedena je sljedećim mjernim tehnikama: infracrvenom spektroskopijom (FT-IR), ultraljubičastom/vidljivom spektroskopijom (UV/Vis), pretražnom mikroskopijom s emisijom elektrona s pomoću polja (FE-SEM), energijski razlučujućom rendgenskom spektrometrijom (EDS) te rendgenskom difrakcijom (XRD). Rezultati svih tehnika potvdili su uspješnu ugradnju Fe3+ iona u kristalnu rešetku ZnO. Prema EDS rezultatima ugradnja Fe3+ iona odvija se do 1 at.%. Koncentracija Fe3+ primjesa ima značajan utjecaj, prema svim rezultatima, na morfološka, strukturna, optička i poluvodička svojstva ZnO. Utjecaj lužine na mehanizam kristalizacije nedopiranih i dopiranih čestica ZnO također je vidljiv iz dobivenih rezultata. Morphological, structural, optical, and semiconducting properties of ZnO particles have been investigated in this work. The influence of Fe3+ doping on mentioned characteristics was in the focus of investigations. Iron doped ZnO samples were prepared by varying the Fe3+ concentration in the range from 0,5 to 5 at.%. The hydrothermal route has been chosen as a simple, reproducible and environmental friendly synthesis procedure of ZnO formation in NH4OH and NaOH media. The samples were characterized by following techniques: infrared spectroscopy (FT-IR), ultraviolet/visible spectroscopy (UV/Vis), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). The results of all techniques have confirmed the incorporation of Fe 3+ ions in the ZnO crystal lattice. According to the EDS results maximum amount of incorporated Fe3+ ions is 1 at.%. The Fe3+ dopant concentration has been correlated with morphological, structural, optical, and semiconducting properties of ZnO. The influence of synthesis medium (NH4OH and NaOH) on the crystallization mechanism is also evident from obtained results.

Proučavan je utjecaj jednovalentnog iona litija i trovalentnog iona cerija na tijek kristalizacije i fotokatalitičku aktivnost perovskita. Kodopirani perovskit, Ca1-2x LixCexTiO3 (x=0,00-0,04) pripravljen je sol gel procesom te termičkom obradom pri 500 °C u trajanju od 2 sata. Tijek kristalizacije, fazni sastav, morfologija i kemijski sastav pripremljenih uzoraka ispitani su rendgenskom difrakcijom praha (XRD), infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR-ATR), simultanom termičkom analizom (STA), energijski razlučujućom rendgenskom spektroskopijom (EDS) te elektronskim pretražnim mikroskopom (SEM). Učinkovitost fotokatalitičke razgradnje metilenskog plavila (MB) praćena je mjerenjem apsorbancije UV-VIS spektroskopijom te je utvrđeno da je najveća za uzorak s najvećim udjelom dopanata. In this paper the effects of monovalent lithium and trivalent cerium ion codoping on crystallization path and photocatalytic activity of CaTiO3 were investigated. Codoped perovskite Ca1-2x LixCexTiO3 (x=0,00-0,04) powder were prepared by sol–gel method followed by thermal treatment at 500 °C for 2 h. Crystallization path, phase composition, morphology and chemical composition of the prepared samples were characterized by various methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), simultaneous thermal analysis (STA), electron dispersive spectroscopy (EDS) and UV–vis spectroscopy. Photocatalytic activity of CaTiO3 was investigated via measuring the photodegradation of methylene blue under UV light irradiation and it was established that activity is greatest for sample with greatest rate of dopants.

Bizmut-ferit (BiFeO3) ispoljava jedinstvena svojstva koja pre svega doprinose teorijskom shvatanju električnih i magnetnih uređenja i njihove interakcije u kristalnim oksidnim materijalima, ali bi uz prevazilažanje trenutno postojećih prepreka materijala na bazi bizmut-ferita mogli naći primenu u mnogim oblastima. Postoji samo nekoliko jednofaznih materijala kojima se može pripisati više feroičnih svojstava (feroelektrična, feroelastična, (anti)feromagnetna) na temperaturama višim od 50 K. Zbog toga ne čudi da je baš bizmut-ferit, koji i na temperaturama iznad sobne može ispoljiti feroelektričnost, feroelastičnost, pa čak i slab feromagnetizam (iako je po magnetnoj strukturi antiferomagnetan), predmet istraživanja brojnih naučnih radova iako i dalje ne postoje uređaji koji u sastavu sadrže bizmut-ferit... Bismuth ferrite (BiFeO3) theoretically possesses very peculiar properties, and understanding them may be the key of understanding the nature of interaction between electrical and magnetic orderings in crystalline oxides. If problems in exhibiting those properties were overcome, bismuth ferrite-based materials might be widely applicable. Few single phase materials exhibit two or three of the ferroic properties (ferroelectric, ferroelastic, (anti)ferromagnetic) at temperatures above 50 K. Being ferroelectric, ferroelastic and even weakly ferromagnetic (although possessing antiferromagnetic structure of magnetic spins) at temperatures well above the room temperature, bismuth ferrite is the subject of hundreds of scientific studies with good reason, although its application is still far from being realized...

Cerijev (IV) oksid (CeO2) najveću primjenu ima u katalitičkim reakcijama kao katalizator i kao nosač katalizatora u mnogim industrijskim procesima, a također i za smanjenje emisije štetnih plinova tako što katalizira reakcije oksidacije metana i ugljikovog monoksida. Dopiranje bakrom znatno poboljšava toplinsku stabilnost CeO2, što proširuje mogućnosti njegove primjene bez straha da će doći do prekomjernog sinteriranja. Hidrotermalnom sintezom pri 120 °C u vremenu od 16 h, uz korištenje 8 mol/L NaOH kao otapala dobiven je čisti CeO2, kao i bakrom dopirani CeO2 s molarnim udjelima bakra 5, 10, 15, 20, 25 te 30 %. Provedbom rendgenske difrakcijske analize (XRD) te infracrvene spektroskopije s Fourierovom transformacijom (FTIR) praćena je struktura produkata, veličina kristalita, parametar jedinične ćelije te način ugradnje bakra u strukturu CeO2. Iz podataka dobivenih eksperimentalnom analizom vidljivo je da se bakar ugrađuje u kristalnu rešetku CeO2 te zamjenjuje ione Ce4+ u unutrašnjosti rešetke, što rezultira smanjenjem veličine kristalita s povećanjem udjela bakra i to od 4,15 nm za čisti CeO2 do čak 3,1 nm za uzorak s 20 mol. % bakra. Iz difraktograma i FTIR spektara je vidljivo da s povećanjem udjela bakra ne dolazi do nastajanja nove faze koja bi ukazivala na formiranje CuO. Ceria is mostly used in catalytic reactions both as catalyst and catalyst support in many industrial processes, and also to lower the emission of harmful gasses by catalyzing oxidation reactions of methane and CO. Adding copper as a doping material enhances the thermal stability, which leads to wider synthesis and processing options without fear of excessive sintering. Products of pure ceria and copper-doped ceria in 5, 10, 15, 20, 25 and 30 mol. % of copper were prepared by hydrothermal synthesis at 120 °C for 16 h, using 8 mol/L NaOH as solvent. Using X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR), the structure of products, crystallite size, unit cell constant and the way of embedding of copper into the CeO2 structure has been investigated. From the data obtained by experimental analyses it was clear that copper, as doping material, enters the ceria crystal structure and replaces Ce4+ ions, which results in smaller crystallite sizes by increasing molar fraction of copper, from 4,15 nm for pure ceria to 3,1 nm for sample with 20 mol. % of copper. From XRD patterns and FTIR spectra it is clear that no matter what molar fraction of copper was introduced into ceria, the CuO was not formed as a side product.

Istraživano je koliki se udio kadmija može ugraditi u kristalnu rešetku cinkita mehanokemijskom sintezom. Kao prekursori su korišteni metalni kloridi i natrijev karbonat dok je natrijev klorid korišten kao razrjeđivač. Nakon mehanokemijske sinteze uzorci su termički obrađeni pri 600 °C u trajanju 2 sata kako bi se iz ZnCO3 dobio ZnO. Pripremljeni uzorci ispitani su rendgenskom difrakcijom praha (XRD), infracrvenom spektroskopijom s Fourierovom transformacijom tehnikom prigušene totalne refleksije (FTIR-ATR), UV-Vis difuznom refleksijskom spektroskopijom (DRS), elektronskim pretražnim mikroskopom (SEM) i energetski razlučujućom rendgenskom spektroskopijom (EDS). Fotokatalitička učinkovitost vrednovana je na temelju procesa razgradnje organske boje metilenskog plavila (MB), praćenog UV-VIS spektroskopijom. Rezultati su pokazali da je mehanokemijskom sintezom iz korištenih prekursora u rešetku cinkita moguće ugraditi do 2 % kadmija, te da se pri većim udjelima kadmija osim cinkita pojavljuju i druge faze poput kadmijeva oksida i kadmijeva karbonata. Dopiranjem cinkita kadmijem dovodi do pojave većih kristalita ZnO. Dopiranjem kadmijem ne postižu se veće promjene u morfologiji, energiji zabranjene zone niti fotokatalitičkoj aktivnosti ZnO. The limit of zincite crystal lattice doping with cadmium in the course of mechanochemical synthesis has been investigated. Metal chlorides and sodium carbonate were used as precursors and sodium chloride as diluent. After mechanochemical synthesis samples were thermally treated at 600 °C for 2 h, in order to enable transformation of ZnCO3 to ZnO. The prepared samples were characterized by X-ray diffraction (XRD), Attenuated total reflectance Fourier-transformed infrared spectroscopy (FTIR-ATR), UV–Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Photocatalytic efficiency has been evaluated through methylene blue (MB) dye degradation process via UV-Vis spectroscopy. The results showed that limit of Zn replacement with Cd in ZnO crystal lattice via mechanochemical synthesis with precursors used is only 2 %. In a presence of larger share of Cd, cadmium oxide or carbonate phases appears. It was noted that doping with Cd impair ZnO nanocrystallinity. No significant differences of ZnO band-gap, morphology and photocatalytic activity with doping were observed.

Cerijev(IV) oksid pokazuje katalitičku aktivnost u procesima oksidacije hlapivih organskih spojeva. Visoka aktivnost cerijevog oksida pripisuje se lakoći Ce4+/Ce3+ redoks reakcije, velikom kapacitetu pohrane kisika i postojanosti kristalne strukture tijekom pohrane i otpuštanja kisika. U odnosu na makromaterijal, nanočestice cerijevog oksida pokazuju povećanu katalitičku aktivnost, a katalitička se svojstva mogu dodatno poboljšati dopiranjem metalnih iona u kristalnu rešetku CeO2. U ovom radu prikazana je hidrotermalna sinteza manganom dopiranih nanočestica cerijevog oksida. Uzorci su toplinski obrađeni pri 500 °C u trajanju od 2 h, a zatim su obrađeni i neobrađeni uzorci podvrgnuti rendgenskoj difrakcijskoj (XRD) analizi. Toplinska stabilnost procijenjena je iz porasta veličine kristalita izračunate iz Scherrerove jednadžbe. Pripremljene nanočestice karakterizirane su pomoću infracrvene spektroskopije s Fourierovom transformacijom (FTIR) i adsorpcijskodesorpcijskih N2 izotermi, a katalitička aktivnost određena je na temelju procesa oksidacije toluena. Utvrđeno je da tijekom hidrotermalne sinteze mangan ulazi u kristalnu rešetku cerijevog oksida. Veličina kristalita nakon hidrotermalne sinteze bila je 4, 8 nm, a nakon toplinske obrade 7, 6 nm. Utvrđeno je da je dopiranjem CeO2 s Mn došlo do poboljšanja katalitičkih svojstava CeO2.

The aim of this doctoral dissertation is chemical synthesis of titania based catalyst in forms of thin film and powder. Catalysts in the form of a thin film were prepared by the dip coating technique using an evaporation-induced, self-assembly method (EISA), with the use of selected polymers as a template (Pluronic F127 and PSM02). Titania based catalysts in powder form were prepared by modified sol-gel method. Catalysts were then modified with a selected dopant (ZrO2). The effects of various process parameters during the synthesis process of the catalysts were studied such as: pH value, calcination temperature etc. In addition, a number of key parameters in the preparation of TiO2 in the form of thin film as well as the (gas) atmosphere for the activation of the catalyst were also considered. Q4.16.01 - Izdawe 1 A complete physico-chemical characterization of photocatalysts (investigation of textural, structural, morphological, thermal, surface properties of the catalysts) was performed. The catalysts were tested in the reactions of the photocatalytic degradation and/or conversion of selected dyes (methylene blue and crystal violet) and the degradation and/or conversion of the selected pesticide (2,4- dichlorophenoxyacetic acid). Various process parameters were investigated such as: the impact of the initial concentrations of pollutants, the number of repeated cycles of reaction, the catalyst amounts, the wavelength of radiation, duration of UV irradiation treatment, pH of the tested solution in order to optimize the process parameters. In addition, the antimicrobial activity, against selected bacterial species, of the synthesized TiO2-based materials in the form of powder and thin film was investigated. The obtained results were discussed in order to determine the optimum process parameters of the photocatalytic reactions, and to achieve a more favorable degradation effect or conversion of pollutants. Physico-chemical characteristics of the obtained catalyst materials have been associated (correlated) with photocatalytic efficiency/activity. Optimisation refers to the complete design and synthesis of (different) titania based catalysts, followed by physico-chemical properties of the catalysts and numerous process parameters of the photocatalytic process in the application of heterogeneous catalysts.

$α-MnO_2$ nanorods were synthesized via the hydrothermal decomposition of $KMnO_4$ in an acidic environment in the presence of $Co^{2+}$ and $Cr^{3+}$ ions. Reactions were carried out at three different temperatures: 90, 130 and 170 °C. All prepared samples exhibit a tetragonal $MnO_2$ crystalline phase. SEM–EDS analysis shows that cobalt cations are incorporated to a higher degree into the $MnO_2$ framework than chromium ions, and that the content of the dopant ions decreases with increasing reaction temperature. The oxidation of $Co^{2+}$ to $Co^{3+}$ during the reaction was proved by an XANES study, while EXAFS results confirm that both dopant ions substitute $Mn^{4+}$ in the center of an octahedron. The K/Mn ratio in the doped samples synthesized at 170 °C is significantly lower than in the undoped samples. Analysis of an individual cobalt-doped $α-MnO_2$ nanorod with HAADF-STEM reveals that the distribution of cobalt through the cross-section of the nanorod is uniform. The course of thermal decomposition of the doped nanorods is similar to that of the undoped ones. Dopant ions do not preserve the $MnO_2$ phase at higher temperatures nor do they destabilize the cryptomelane structure.

Cilja doktorske disertacije sta bila razvoj fotokatalitsko aktivnega TiO2 v rutilni kristalni modifikaciji na vidni svetlobi in razvoj UV absorberja rutilnega TiO2, ki je fotokatalitsko neaktiven. S tem namenom smo v okviru doktorske disertacije poiskali dopanta, ki sta ustrezno modificirala kristalno strukturo TiO2. Proučili smo vpliv kovinskih in nekovinskih dopantov na fotokatalitsko delovanje TiO2, za kar smo uporabili rutilno kristalno modifikacijo TiO2 in hidrotermalno metodo. Pred tem smo z uporabo hidrotermalne metode proučili različne pogoje za nastanek monokristaliničnih rutilnih TiO2 delcev. Za proučevanje kovinskih dopantov smo uporabili ione Fe, Mn in Cu. Ugotovili smo, da uporabljeni kovinski dopanti inhibirajo fotokatalitsko delovanje TiO2, vendar se v učinkovitosti inhibicije razlikujejo. Dopant, ki najučinkoviteje inhibira fotokatalitsko aktivnost TiO2, je Mn. Pri inkorporaciji kovinskih dopantov v kristalno rešetko TiO2 smo znižali energijsko vrzel in premaknili absorpcijski rob dopiranih vzorcev v vidni del svetlobnega spektra. Pri proučevanju vpliva nekovinskih dopantov na povišanje fotokatalitske aktivnosti rutilnega TiO2 smo proučili ione dopantov N in S. Pri nekovinskih dopantih ne velja splošno pravilo o povišanju fotokatalitske aktivnosti. Rezultati kažejo, da ioni dopanta S znižajo fotokatalitsko aktivnost TiO2, medtem ko ioni N učinkovito zvišajo fotokatalitsko aktivnost v UV in vidnem delu svetlobnega spektra. Ugotovili smo, da z dopiranjem rutilnega TiO2 z N lahko izdelamo fotokatalizator, ki deluje na vidni svetlobi. Pri inkorporaciji nekovinskih dopantov ne pride do znižanja energijske vrzeli, kot tudi ne do večjega premika absorpcijskega roba v vidni del svetlobnega spektra. Dopant N se intersticijsko vgradi v kristalno rešetko. Rutilna kristalna modifikacija je bila na področju razvoja fotokatalizatorja na vidni svetlobi do sedaj v ozadju, saj ni izkazovala dobrih fotokatalitskih lastnosti. Z našimi preliminarnimi raziskavami pa smo ugotovili, da rutilna kristalna modifikacija izkazuje višjo fotokatalitsko aktivnost kot anatasna. Z razvojem rutilnega vidnega fotokatalizatorja smo rutilni kristalni modifikaciji pripisali velik pomen na področju fotokatalize. Hkrati pa smo tudi razjasnili vpliv uporabe kovinskih in nekovinskih dopantov na fotokatalitsko aktivnost rutilnega TiO2 ob uporabi hidrotermalne sinteze. Naši izsledki imajo pomemben doprinos k razvoju znanosti na tem področju. The aim of the present work was to develop a photocatalytically active rutile TiO2 under visible light conditions. Furthermore, the aim was also to develop a UV absorber based on rutile TiO2 that would have no observable photocatalytic activity. To achieve the aims of the present work, we focused our examination on finding appropriate dopants that enable the modification of rutile crystal structure and thus influence its photocatalytic activity. We investigated incorporation of both metal and nonmetal dopants and their respective influence on the photocatalytic activity of rutile TiO2. The doping of rutile TiO2 was carried out using the hydrothermal method. The hydrothermal method was also used to study various synthesis parameters and their influence on the formation of monocrystalline particles. Metals dopants used in the present study were ions of Fe, Mn and Cu. We have determined that the used metal ions inhibit the photocatalytic activity of TiO2 and that the level of inhibition varies on the type of metal dopant. The most effective metal dopant to inhibit the photocatalytic activity is Mn. We have also found out that when metal ions are incorporated into the crystal lattice, the TiO2 bandgap is lowered and the absorption edge is shifted into the visible light range. To enhance the photocatalytic activity of TiO2, we used nonmetal dopants, N and S. We have found that there is no general rule on how the nonmetal dopants influence the photocatalytic activity of TiO2, since our results show that S dopant lowers, while N dopant effectively enhances the photocatalytic activity in both UV and visible light spectra, respectively. By incorporating N dopant into the TiO2 crystal lattice, we were able to produce a photocatalyst that is active in visible light spectra. We determined that nonmetal dopants do not lower the TiO2 bandgap and also do not shift the TiO2 absorption edge at the visible light wavelength position. We conclude that N ions are interstitially incorporated into the TiO2 crystal lattice. Based on the literature overview, it was clearly observed, that the rutile TiO2 modification was not regarded as a potentially suitable visible light photocatalyst, since the observed activities were mostly lower than with anatase. Our findings, however, have shown that by using appropriate dopants, rutile TiO2 can be transformed into a superior photocatalyst than anatase. Therefore, the rutile TiO2 can be a potentially very important material that enables visible light photocatalytic activity. In our work we have also clarified the influence of both metal and nonmetal dopants on the TiO2 photocatalytic activity of materials prepared by using the hydrothermal method. Our findings are therefore a major contribution in the field of heterogenous photocatalysis.

Kalcijum-fosfati čine neorganski deo kostiju i zuba sisara. Ova dobro poznata činjenica je ohrabrila istraživače da tokom prethodnih godina primene sintetisani kalcijum-hidroksiapatit (HAp, Ca10(PO4)6(OH)2) i kalcijum-fosfat (TCP, Ca3(PO4)2), α- i β-TCP faze, kao implantne materijale. Njihova sličnost sa neorganskim delom kostiju je potvrđena, a posebno je istaknuta njihova biokompatibilnost i osteokonduktivnost i dodatno bioaktivnost HAp-a i bioresorpcija TCP-a. Dvofazne forme (BCP): HAp/β-TCP i HAp/α-TCP, kao i trifazna forma HAp/β-TCP/α-TCP, pokazale su se kao bolji biomaterijali nego pojedinačne faze i posebno su interesantne za dalja istraživanja. U cilju dobijanja biomaterijala sa antimikrobnim efektom, prahovi HAp-a dopirani jonima Ag+, Cu2+ ili Zn2+ su sintetisani hidrotermalnom metodom pri čemu je odnos Ca/P iznosio 1,67. U sintezama molski udeo dopanata iznosio je 0,2, odnosno 0,4 mol% sa ciljem da se dobiju prahovi sa dobrom antimikrobnom aktivnošću uz očuvanje biokompatibilnosti. Dopirani prahovi HAp-a su kalcinisani na 1200 °C tokom 2 h sa namerom da se ispita uticaj dopiranja na stvaranje dvofaznih prahova HAp/α-TCP, kao i antimikrobna aktivnost i biokompatibilnost tako dobijenih prahova. Za analizu svih prahova, nedopiranih i dopiranih HAp i HAp/α-TCP, korišćeni su visokorezolucioni skenirajući elektronski mikroskop (FESEM), rendgenska difrakcija (XRD), infracrvena spektroskopija sa Furijeovom transformacijom (FTIR), atomska apsorpciona spektroskopija (AAS) i energetska disperziona spektroskopija (EDS). Termička analiza sintetisanih prahova je sprovedena u cilju određivanja faznih transformacija tokom zagrevanja do 1200 °C. Antibakterijska aktivnost prahova ispitana je u in vitro uslovima u odnosu na mikroorganizme: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) i Candida albicans (C. albicans). Svi prahovi su pokazali dobru antimikrobnu aktivnost, s tim da su prahovi dopiranih HAp/α-TCP dali malo bolje rezultate u odnosu na sve patogene mikroorganizme nego dopirani HAp prahovi. In vitro testovi biokompatibilnosti, kolorimetrijski test sa tetrazolijum solima (MTT) i test odbacivanja boje (DET), su korišćeni da bi se procenila biokompatibilnost dopiranih HAp/α-TCP prahova sa MRC-5 humanim fibroblastnim ćelijama. Ovi testovi su potvrdili da dati prahovi nemaju citotoksični efekat. Posebno dobru biokompatibilnost su pokazali prahovi HAp/α-TCP dopirani nižim udelom jona Ag+, Cu2+ i Zn2+. Na osnovu testova antimikrobne aktivnosti i biokompatibilnosti zaključeno je da su dopirani HAp/α-TCP prahovi obećavajući materijal za korišćenje u rekonstruktivnoj hirurgiji kostiju... Calcium phosphates constitute the inorganic part of bones and teeth of mammals. This fact is well known and has encouraged researchers to apply hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and tricalcium phosphate (TCP, Ca3(PO4)2), both α- and β-TCP, over the past years as implant materials. Their similarity to the inorganic part of hard tissues has been confirmed, highlighting their biocompatibility and osteoconductivity and, in addition, the bioactivity of HAp and the bioresorbability of TCP. The biphasic forms (BCP): HAp/β-TCP and HAp/α-TCP and the triphasic form HAp/β-TCP/α-TCP, which were proved to be even better biomaterial than single phases, are of particular interest. Hydroxyapatite (HAp) powders doped with Ag+, Cu2+ or Zn2+ were synthesized by a hydrothermal method, at a Ca/P ratio of 1.67, in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (0.2 or 0.4 mol %) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping on the creation of biphasic HAp/α-TCP and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), Atomic absorption spectroscopy (AAS) and Energy-dispersive X-Ray spectroscopy (EDS). Thermal analysis of the synthesized powders was performed to evaluate the phase transformations during heating up to 1200 °C. The in vitro antibacterial activities of the powders were evaluated against the pathogenic microorganisms: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP demonstrated better results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that the powders did not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag+, Cu2+ and Zn2+ ions showed especially good biocompatibility. The antimicrobial and biocompatibility tests recommend the doped HAp/α-TCP as promising material for use in reconstructive surgery of bones...

V magistrski nalogi je predstavljen OLED element in njegova uporaba v sodobnih aplikacijah. Na začetku je opisana kratka zgodovina raziskav OLED elementov in njihovega uvajanja v praktičnih aplikacijah. Nato je predstavljena osnovna in bolj kompleksna struktura OLED elementov ter njihovo delovanje. Definiran je tudi izkoristek OLED elementov in opisano, kako se da izkoristek povečati s pomočjo dopiranja. Podani so tudi najpogosteje uporabljeni materiali za posamezne sloje OLED elementov. V nadaljevanju je predstavljena ena glavnih aplikacij OLED elementov za TV zaslone in kratka primerjava OLED zaslonov z LCD zasloni. Opisan je proces izdelave OLED TV zaslonov in tudi tipi zaslonov, ki obstajajo na tržišču. V zaključnem delu naloge smo opisali, kako lahko OLED elemente uporabljamo kot velikopovršinske svetlobne panele, v kakšnih aplikacijah bi jih lahko uporabili in težave, ki jih srečujejo proizvajalci pri njihovi izdelavi. Narejena je tudi primerjava med organsko svetlečo diodo in anorgansko svetlečo diodo. In this master thesis is presented the OLED element and its use in modern application. In the beginning we describe a short history, when and how the first research in using OLED elements began and when and in which applications it first appeared. Then we presented the basic and more complex structure of the OLED element and how it works. We also defined the efficiency of the OLED element and describe how to increase this efficiency using a doping method. Given are also the most frequently used materials for each layer of the OLED element. Further we present one of the main applications of the OLED element, that is in TV screens and a short comparison between OLED displays and LCD displays. We described the process of making OLED TV screens and what types of displays exist on the market. In the final part of the paper we described how to use OLED elements for large area OLED lighting panels and in which applications we could use them in and the difficulties encountered by the manufacturers in their creation. Then there is a comparison made between an organic light emitting diode and an inorganic light emitting diode

Calcium phosphates constitute the inorganic part of bones and teeth of mammals. This fact is well known and has encouraged researchers to apply hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and tricalcium phosphate (TCP, Ca3(PO4)2), both α- and β-TCP, over the past years as implant materials. Their similarity to the inorganic part of hard tissues has been confirmed, highlighting their biocompatibility and osteoconductivity and, in addition, the bioactivity of HAp and the bioresorbability of TCP. The biphasic forms (BCP): HAp/β-TCP and HAp/α-TCP and the triphasic form HAp/β-TCP/α-TCP, which were proved to be even better biomaterial than single phases, are of particular interest. Hydroxyapatite (HAp) powders doped with Ag+, Cu2+ or Zn2+ were synthesized by a hydrothermal method, at a Ca/P ratio of 1.67, in order to obtain biomaterial with an antimicrobial effect. The synthesis was performed with two contents of dopant (0.2 or 0.4 mol %) by considering both the antimicrobial activities and biocompatibility of the powders. The doped HAp was annealed at 1200 °C for 2 h with the intention of investigating the influence of doping on the creation of biphasic HAp/α-TCP and determining the antimicrobial activity and biocompatibility of the obtained biphasic powders. Analyses of all powders, undoped and doped HAp and HAp/α-TCP, were performed by Field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), Atomic absorption spectroscopy (AAS) and Energy-dispersive X-Ray spectroscopy (EDS). Thermal analysis of the synthesized powders was performed to evaluate the phase transformations during heating up to 1200 °C. The in vitro antibacterial activities of the powders were evaluated against the pathogenic microorganisms: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. All powders showed good antimicrobial activity but generally the powders of doped HAp/α-TCP demonstrated better results against all pathogenic microorganisms than the powders of doped HAp. In vitro biocompatibility tests, MTT and DET, were used to evaluate the biocompatibility of doped HAp/α-TCP with MRC-5 human fibroblast cells. These tests confirmed that the powders did not have a cytotoxic effect. The HAp/α-TCP powders doped with the lower content of Ag+, Cu2+ and Zn2+ ions showed especially good biocompatibility. The antimicrobial and biocompatibility tests recommend the doped HAp/α-TCP as promising material for use in reconstructive surgery of bones... Kalcijum-fosfati čine neorganski deo kostiju i zuba sisara. Ova dobro poznata činjenica je ohrabrila istraživače da tokom prethodnih godina primene sintetisani kalcijum-hidroksiapatit (HAp, Ca10(PO4)6(OH)2) i kalcijum-fosfat (TCP, Ca3(PO4)2), α- i β-TCP faze, kao implantne materijale. Njihova sličnost sa neorganskim delom kostiju je potvrđena, a posebno je istaknuta njihova biokompatibilnost i osteokonduktivnost i dodatno bioaktivnost HAp-a i bioresorpcija TCP-a. Dvofazne forme (BCP): HAp/β-TCP i HAp/α-TCP, kao i trifazna forma HAp/β-TCP/α-TCP, pokazale su se kao bolji biomaterijali nego pojedinačne faze i posebno su interesantne za dalja istraživanja. U cilju dobijanja biomaterijala sa antimikrobnim efektom, prahovi HAp-a dopirani jonima Ag+, Cu2+ ili Zn2+ su sintetisani hidrotermalnom metodom pri čemu je odnos Ca/P iznosio 1,67. U sintezama molski udeo dopanata iznosio je 0,2, odnosno 0,4 mol% sa ciljem da se dobiju prahovi sa dobrom antimikrobnom aktivnošću uz očuvanje biokompatibilnosti. Dopirani prahovi HAp-a su kalcinisani na 1200 °C tokom 2 h sa namerom da se ispita uticaj dopiranja na stvaranje dvofaznih prahova HAp/α-TCP, kao i antimikrobna aktivnost i biokompatibilnost tako dobijenih prahova. Za analizu svih prahova, nedopiranih i dopiranih HAp i HAp/α-TCP, korišćeni su visokorezolucioni skenirajući elektronski mikroskop (FESEM), rendgenska difrakcija (XRD), infracrvena spektroskopija sa Furijeovom transformacijom (FTIR), atomska apsorpciona spektroskopija (AAS) i energetska disperziona spektroskopija (EDS). Termička analiza sintetisanih prahova je sprovedena u cilju određivanja faznih transformacija tokom zagrevanja do 1200 °C. Antibakterijska aktivnost prahova ispitana je u in vitro uslovima u odnosu na mikroorganizme: Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) i Candida albicans (C. albicans). Svi prahovi su pokazali dobru antimikrobnu aktivnost, s tim da su prahovi dopiranih HAp/α-TCP dali malo bolje rezultate u odnosu na sve patogene mikroorganizme nego dopirani HAp prahovi. In vitro testovi biokompatibilnosti, kolorimetrijski test sa tetrazolijum solima (MTT) i test odbacivanja boje (DET), su korišćeni da bi se procenila biokompatibilnost dopiranih HAp/α-TCP prahova sa MRC-5 humanim fibroblastnim ćelijama. Ovi testovi su potvrdili da dati prahovi nemaju citotoksični efekat. Posebno dobru biokompatibilnost su pokazali prahovi HAp/α-TCP dopirani nižim udelom jona Ag+, Cu2+ i Zn2+. Na osnovu testova antimikrobne aktivnosti i biokompatibilnosti zaključeno je da su dopirani HAp/α-TCP prahovi obećavajući materijal za korišćenje u rekonstruktivnoj hirurgiji kostiju...

Multiferoici su multifunkcionalni materijali koji pokazuju istovremeno više parametara uredenja. Međusobna povezanost tih uređenja, pogotovo fero- električnog i magnetskog otvara mogućnost tehnološe upotrebe. U ovom radu istraživana su magnetska svojstva perovskitnog multiferoika BiFeO3 dopiranog s različitim postotcima gadolinija pomoću MPMS SQUID magnetometra. Osim uobičajenih niskotemperaturnih magnetskih svojstava pomoću posebnog dodatka za MPMS SQUID magnetometar izmjerena su visokotemperaturna svojstva uzoraka, u intervalu od 2 do 800 K. Opažen je fazni prijelaz na 640 K koji opada do 635 K sa pove ćanjem koncentracije gadolinija te veliko razdvajanje ZFC i FC krivulja koje potječe od slabog feromagnetskog uredenja. Magnetske histereze su mjerene do polja od 5 T gdje nije bilo znakova saturacije. BiFeO3 ima antiferomagnetske histereze sa malim koercitivnim poljima koje opada sa porastom temperature, dok dopirani uzorci pokazuju veliko koercitivno polje koje u odredenom temperaturnom intervalu neuobičajeno raste sa porastom temperature. Mjerenja u električnom polju su pokazala male promjene u iznosu magnetizacije, ali ne i promjene u ponašanjima magnetizacije, ukazujući na čvrstu magnetsku strukturu. BiFeO3 dopiran gadolinijem ima veći magnetski moment od antiferomagnetskog, čistog, BiFeO3 , ali dopiranjem nije postignuto primjetljivo magnetoelektrično vezanje. Iako je BiFeO3 jedan od rijetkih multiferoika na sobnoj temperaturi, njegova tehnološka upotreba je stoga ograničena zbog malog magnetoelektričnog efekta, čak i u slučaju izazvanog slabog feromagnetizma prilikom provedenog dopiranja.

In the first part of dissertation structural, microstructural and phase analysis of the nanopowders with the general formula Ca1-xYxMnO3 (0 ≤ x ≤ 1) were performed using XRPD diffraction technique and Rietveld refinement. The most abundant crystal phases in these nanopowders are the members of ABO3 solid solutions with the perovskite structure type. Seven nanopowders of nominal composition CaMnO3 (Ca100), Ca0.95Y0.05MnO3 (Ca95), Ca0.85Y0.15MnO3 (Ca85), Ca0.75Y0.25MnO3 (Ca75), Ca0.5Y0.5MnO3 (Ca50), Ca0.25Y0.75MnO3 (Ca25) and YMnO3 (Y100) were prepared using a modified glycine/nitrate process. Yttrium doped CaMnO3 crystallizes in the space group Pnma, and one of the goals of the research is to investigate the stability of the perovskite structure type depending on the dopant concentration. Two phase composition of all samples and amount of each phase was revealed using XRPD diffraction and Rietveld refinement. The most abundant phase in all samples has the perovskite structure type. As a result of doping with Y, the XRPD analysis showed that all the perovskite phases are deformed, with symmetry reduced from cubic to orthorhombic, and that they crystallize in the Pnma space group. Unit cell parameters analysis showed that the increase of the unit cell parameters, which is related to the higher amount of Y in the structure, is a consequence of reduction of Mn4+ to Mn3+. Besides the reduction of the Mn and the effect of doping with Y, presence of vacancies in the structure also affects the mechanism of this transformation. The chemical compositions, calculated from the refined occupancy values, are compared with nominal compositions. Effect of yttrium on the bond lengths and bond angles, tilting and deformation of octahedra caused by presence of Mn3+ and Jahn-Teller effect, was analyzed. In order to investigate the coordination of the A and B sites, bond valence analysis was performed. In addition, concentration of yttrium in the doped perovskite phases was investigated using X-ray photoelectron spectroscopy (XPS). In the second part of dissertation we have performed a crystal structure prediction study of CaMnO3 focusing on structures generated by octahedral tilting according to group-subgroup relations from the ideal perovskite type ( Pm3m), which 173 is the aristotype of the experimentally known CaMnO3 compound in the Pnma space group. Using software SPuDS we obtained initial structure parameters for most of the perovskite structure candidates. Furthermore, additional structure candidates have been obtained using data mining. For each of the structure candidates, a local optimization on the ab initio level using density functional theory (LDA and hybrid B3LYP) and the Hartree-Fock (HF) method was performed, and we find that several of the modifications may be experimentally accessible. In the high-pressure regime, we have identified a post-perovskite phase in the CaIrO3 type, not previously observed in CaMnO3. Similarly, calculations at negative pressure predicted a phase transition from the orthorhombic perovskite to an ilmenite-type (FeTiO3) modification of CaMnO3.

U disertaciji je opisano dobijanje velikog broja faza sa silenitskom (γ-Bi2O3) i defektnom fluoritskom (δ-Bi2O3) strukturom, ispitivanih u pseudo-binarnim sistemima Bi2O3–MxOy, gde je M = Ag, Li, Pb, Zn, Al, Fe, Tm, Ce, Hf, Mn, Si, Ti, V, W i Cr, i pseudo-ternarnim sistemima Bi2O3–M1xOy–M2xOy, gde je M1 = Pb, Zn i Ti, M2 = Zn, Ti i Si. Glavni sintetski postupak bio je termohemijski, a korišćene su sledeće metode karakterizacije: rendgenska difrakcija na polikristalnim uzorcima, diferencijalna termijska analiza, skenirajuća elektronska mikroskopija, rendgenska spektroskopija sa skeniranjem energija, transmisiona elektronska mikroskopija visoke rezolucije, elektronska difrakcija i elektrohemijska impedansna spektroskopija... Numerous phases with sillenite (γ-Bi2O3) and defect fluorite (δ-Bi2O3) structure have been prepared in pseudo-binary Bi2O3–MxOy systems, where M = Ag, Li, Pb, Zn, Al, Fe, Tm, Ce, Hf, Mn, Si, Ti, V, W, Cr, and pseudo-ternary Bi2O3–M1xOy–M2xOy systems, where M1 = Pb, Zn, Ti and M2 = Zn, Ti, Si. The products mainly prepared by high-temperature reactions were characterized by the following techniques: X-ray powder diffraction, differential thermal analysis, scanning electron microscopy, energydispersive X-ray spectroscopy, high resolution transmission electron microscopy, selected area electron diffraction and electrochemical impedance spectroscopy...

Sintetisani su modifikovani TiO2 fotokatalizatori hidrotermalnom metodompotpomognutom mikrotalasima za tretman otpadne vode iz tekstilne industrije. Fotokatalitičkaaktivnost katalizatora je procenjena na osnovu dekolorizacije reaktivne tekstilne boje ReactiveBlue 52 pomoću lampe sa Sunčevim spektrom zračenja.U prvom delu rada sintetisani su TiO2 katalizatori dopirani jonima La i kodopiranijonima La i V. Utvrđeno je da svi sintetisani katalizatori imaju mezoporoznu strukturu i dajoni oba dopanta utiču na morfološke i teksturalne osobine, povećavaju specifičnu površinu izapreminu pora, a smanjuju veličinu agregata. Dodatak V utiče na produženje apsorpcijekatalizatora u vidljivi deo spektra. Optimalna količina jona La kao dopanta je 2% i daljepovećanje sadržaja La vodi do smanjenja efikasnosti katalizatora, pa je katalizator sa 2% Laodabran za kodopovanje vanadijumom. Dodatak jona V u kodopiranim uzorcima dodatnodoprinosi povećanju fotokatalitičke aktivnosti i kao najefikasniji se pokazao katalizator sa 2%La i 0,02% V. Ispitivanjem uticaja početne koncentracije boje i katalizatora na dekolorizacijusa najefikasnijim katalizatorom, pokazalo se da procenat dekolorizacije opada sa povećanjempočetne koncentracije boje, a da se dekolorizacija povećava sa povećanjem koncentracijekatalizatora do jedne određene tačke, gde dostiže maksimum. Ovaj katalizator je pokazaoveću aktivnost i brzinu sedimentacije od komercijalno dostupnog Degussa P25 i mogućnostkorišćenja u više ciklusa bez gubitka aktivnosti, što čini ovaj katalizator prihvatljivim i zaindustrijsku primenu.U drugom delu rada je ispitana mogućnost primene TiO2 katalizatora dopiranogjonima Fe u heterogenom foto-Fentonskom procesu. Dopiranjem TiO2 jonima Femikrotalasno hidrotermalnom metodom dobijeni su materijali velike specifične površine irazvijene strukture mezopora i mikropora. Uočeno je da povećanje sadržaja jona Fe dovodi dopomeranja apsorcije katalizatora ka većim talasnim dužinama, u vidljivi region. Rezultatiispitivanja efikasnosti katalizatora za dekolorizaciju tekstilne boje su pokazali da katalizatordopiran Fe jonima ima veću aktivnost od nedopiranog TiO2. Prisustvo H2O2 povećavafotokatalitičku efikasnost kada se upotrebi u procesu sa TiO2, a u slučaju dopiranogkatalizatora sa 3,4% Fe, dodatak H2O2 povećava efikasnost u većoj meri nego za čist TiO2. Toznači da H2O2 zajedno sa dopiranim katalizatorom učestvuje u heterogenom foto-Fentonskomprocesu. Ispitivanjem uticaja količine dopanta na procenat dekolorizacije, došlo se dozaključka da je optimalna količina Fe 3,4% i pri višim koncentracijama dolazi do padaaktivnosti katalizatora. Rezultati ispitivanja uticaja pH su pokazali da se efikasnost povećavasa smanjenjem pH vrednosti i najbolji rezultati su dobijeni za pH vrednost 3, ali je curenje Fejona izraženo na ovako niskom pH, tako da je pH 4 odabran kao optimalna vrednost. Rezultatisu pokazali da koncentracija H2O2 ima uticaj na procenat dekolorizacije: procenatdekolorizacije se povećava sa povećanjem koncentracije H2O2 do 20 mM, nakon čega daljepovećanje nema značajan uticaj. Ispitivanje uticaja početne koncentracije boje i katalizatora jedalo iste rezultate kao i u slučaju katalizatora kodopiranog jonima La i V. Povećanjekoncentracije boje izaziva smanjenje procenta dekolorizacije, dok veća količina katalizatorapovećava efikasnost do jedne granične vrednosti, kada daljim povećanjem ne doprinosiefikasnosti procesa. Ispitivanjem degradacija 4-hlorfenola u heterogenom foto-Fentonskomprocesu sa najefikasnijim dopiranim TiO2 katalizatorom, 3,4% Fe, došlo se do zaključka da jekatalizator sposoban i za degradacije bezbojnih zagađivača. Ovaj katalizator je pokazao imogućnost ponovne upotrebe u više ciklusa bez gubitka aktivnosti. Uzimajući u obzir svenavedene osobine katalizatora, može se smatrati kao dobar kandidat za upotrebu uremedijaciji zagađenih voda. Modified TiO2 photocatalysts were prepared by a microwave-assisted hydrothermalmethod for the treatment of textile industry wastewater. The photocatalytic activity of thesamples was evaluated by the decolorization of textile dye Reactive Blue 52 in aqueoussolutions under sun-like radiation.La doped and V-La co-doped TiO2 photocatalysts were synthesized. It was found thatall the synthesized catalysts had the mesoporous structure and ions of both dopants influencedmorphological and textural characteristics of the synthesized photocatalysts, increase specificsurface area and pore volume, as well as, reduce the size of aggregates. Vanadium dopingplays a role in extending light absorption into the visible region. The optimal amount oflanthanum doping is 2% and further increase of the lanthanum content leads to the decrease ofphotoactivity. Therefore, the catalyst with 2% of the lanthanum was chosen for co-dopingwith vanadium. The presence of V ions in the co-doped samples additionally contributes toenhancement of photoactivity and the photocatalyst with 2% La and 0.02% V appeared to bethe most photoactive. The effect of the initial dye concentration and catalyst loading with themost efficient catalyst were examined. It was found that percentage of dye removal decreaseswith the increase of initial dye concentration and the degradation increases with the increasingconcentration of the catalyst to a certain point, where it reaches its maximum. The V-La codopedcatalyst showed better photocatalytic activity and sedimentation properties thanDegussa P25 and also, excellent photostability and reusability, which make the V-La codopedcatalyst acceptable for industrial application.It was investigated the applicability of TiO2 catalyst doped with Fe ions inheterogeneous photo-Fenton process. It was found that all Fe doped materials prepared bymicrowave-assisted hydrothermal method have high specific surface area and mesoporousstructure. Fe doping influenced the extension of light absorption into the visible region. Theresults indicate that the addition of Fe contributes to the catalytic activity. The presence ofH2O2 increased the photocatalytic activity with TiO2, but with 3,4% Fe doped TiO2 increasedefficiency to a higher extent. It means that H2O2 has a part in the heterogeneous photo-Fentonprocess. It was found that the optimal amount of Fe doping is 3,4% and further increase of theFe content leads to the decrease of photoactivity. Results indicate that the efficiency increasewith decreasing the pH value and the best results are obtained for pH value 3, but leakage ofFe ions was observed at such low pH, therefore pH 4 was chosen as optimal. The resultsshowed that percentage of dye removal increases with the increase of H2O2 concentration to acertain point, where it reaches its maximum. The effect of the initial dye concentration andcatalyst loading gave the same results as in the case of V-La co-doped catalyst. Degradationof 4-chlorophenol in heterogeneous photo-Fenton process with 3,4% Fe doped catalyst wasexamined. Under the optimal experimental conditions, the catalyst was able to degrade evencolorless pollutant. The catalyst also showed the possibility of recycling without loss ofactivity. Therefore it can be considered as good candidate for wastewaters remediationpurpose.

Numerous phases with sillenite (γ-Bi2O3) and defect fluorite (δ-Bi2O3) structure have been prepared in pseudo-binary Bi2O3–MxOy systems, where M = Ag, Li, Pb, Zn, Al, Fe, Tm, Ce, Hf, Mn, Si, Ti, V, W, Cr, and pseudo-ternary Bi2O3–M1xOy–M2xOy systems, where M1 = Pb, Zn, Ti and M2 = Zn, Ti, Si. The products mainly prepared by high-temperature reactions were characterized by the following techniques: X-ray powder diffraction, differential thermal analysis, scanning electron microscopy, energydispersive X-ray spectroscopy, high resolution transmission electron microscopy, selected area electron diffraction and electrochemical impedance spectroscopy... U disertaciji je opisano dobijanje velikog broja faza sa silenitskom (γ-Bi2O3) i defektnom fluoritskom (δ-Bi2O3) strukturom, ispitivanih u pseudo-binarnim sistemima Bi2O3–MxOy, gde je M = Ag, Li, Pb, Zn, Al, Fe, Tm, Ce, Hf, Mn, Si, Ti, V, W i Cr, i pseudo-ternarnim sistemima Bi2O3–M1xOy–M2xOy, gde je M1 = Pb, Zn i Ti, M2 = Zn, Ti i Si. Glavni sintetski postupak bio je termohemijski, a korišćene su sledeće metode karakterizacije: rendgenska difrakcija na polikristalnim uzorcima, diferencijalna termijska analiza, skenirajuća elektronska mikroskopija, rendgenska spektroskopija sa skeniranjem energija, transmisiona elektronska mikroskopija visoke rezolucije, elektronska difrakcija i elektrohemijska impedansna spektroskopija...