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High-entropy spinel oxides (HESOs) are oxides with 5 or more cations with the general formula AB2O4 and the spinel ( Fd 3m ) structure. Due to their unique structure and properties, HESOs have shown great potential in various technological applications, i.e. they can be used as catalysts, adsorbents and photocatalysts. Since the first successful synthesis in 2018, researchers have been experimenting with different precursors and synthesis methods. However, further research is still needed in order to fully understand their capabilities and exploit their properties. The aim of this research is to synthesize novel HESOs using the self-propagating room temperature (SPRT) method, which is time and cost-effective and has not been utilized so far. Our results indicate that chlorides are not good precursors, since the formation of spinel structure has not been achieved. On the other hand, the use of nitrates has successfully led to a primary spinel ( Fd 3m ) phase. Still, certain issues persist, as secondary phases are commonly formed, especially in the presence of Mg or Cu. A potential solution that could ensure the formation of a single phase is the use of quenching from high temperatures (1000 °C), instead of gradual cooling.

Alumina composite was prepared via simple route. Alumina ceramics that resembels seashells are made of aligned micron-sized monocrystalline platelets joined together by silica secondary phase. SiO2 was added to improve mechanical properties of composite. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD) and thermal analyses. Effect of sintering temperature on mechanical properties, due to the increase of sintering temperature that can produce a higher strength and higher density, was also investigated. SEM observation of composite was also included. Ceramics composites such as this are good candidates for high temperature oxidation atmosphere applications, as they have excellent mechanical and other performance requirements.

In modern industry, there is an increasing demand for environmentally friendly and light structural materials with good physical and mechanical properties, produced from cheap natural raw materials available in large quantities. One of the materials that meet the mentioned criteria is basalt. Basalt is a natural igneous rock of volcanic origin, created by the pouring of magma on the Earth's surface, the amount of which is significant in the territory of Serbia. Since basalt does not exhibit toxic, carcinogenic, or mutagenic effects, it is in the true sense a non-hazardous material and belongs to the group of eco-friendly materials. In this research, andesite basalt aggregate from the "Donje Jarinje" site, in Serbia, was used to obtain high-density glass-ceramic materials. High-density glass-ceramic materials were obtained by powder metallurgy process, which consisted of the following methods: dry grinding, homogenization, cold uniaxial and isostatic powder pressing and sintering in the air. In order to achieve a high-density of the materials, the green compacts were sintered in the temperature range from 1040 to 1080 °C. After confirming that the highest density materials were achieved at the sintering temperature of 1060 °C, the sintering time was optimized in the time interval from 30 to 240 min. After the experimental test, the optimal sintering parameters for obtaining high-density glass-ceramic material at the temperature of 1060 °C for 60 min were achieved, whose relative density is 99.50%, and hardness is 6.70 GPa. The characterization of andesite basalt powder was performed using the laser light diffraction method, scanning electron microscopy and X-ray diffraction method, while the characterization of sintered glass-ceramic materials was performed using the Archimedes method, X-ray diffraction method, optical light microscopy and Vickers hardness test. The results of this research confirmed that by applying powder metallurgy and sintering in the air, high-d

Two series of glass-ceramic composites (basalt/mine tailings, basalt/basalt fibers) as well as one pure glass-ceramic were prepared from basalt rocks located in the SE part of Serbia (Lukovska Banja). Both composites contained 85, 90 and 95 wt.% basalt glass respectively. The basalt glass was obtained from initial melting of basalt at 1300 °C. In the present study, the crystallization process of basalt glass contained in the glass-ceramic composite, achieved by thermal treatment, was observed, and analyzed. The thermal treatment was done at 900 °C, 950 °C, 1000 °C and 1050 °C respectively, with the retention times of 1, 3, 6, 8 and 16 hours. It was found that the addition of mine tailings and basalt fibers caused a change in the density and microstructure. The study also showed that the best mechanical and structural characteristics of the examined glassceramics were attained at the temperature of 1050 °C, with the retention time of 1 hour. Additionally, structural and optical characteristics of the glass-ceramics were assessed.

The industrial requirements in the 21st century are environmentally friendly and light construction materials with good physical-mechanical properties manufactured from cheap natural raw materials available in large quantities. One of these materials is basalt. Basalt is a natural igneous rock of volcanic origin, with a significant amount in Serbia. Basalt belongs to the group of non-hazardous and eco-friendly materials. Andesite basalt aggregate from the "Donje Jarinje" site, Serbia, was used as the starting natural raw material for obtaining the glass-ceramic material. The aggregate is from 2 to 5 mm in size. The aggregate was milled in the tungsten-carbide vibrating cup mill for 30 min to obtain a fine powder for synthesis. The homogenization of andesite basalt powder and binder was carried out in the mortar and pestle for 10 min. The paraplast was used as a binder with a content of 0.6 wt.%. After that, uniaxial pressing of the powder at a pressure of 50 MPa was performed. A forming green compact, cold isostatic pressing was performed with a pressure of 230 MPa to increase its density. The sintering was carried out at the temperature of 1060 °C for 60 min in the air. The sintered glass-ceramic sample was a relative density of 99.5%, a macrohardness of 6.7 GPa and a fracture toughness of 2.2 MPa·m1/2 [1]. The andesite basalt powder was characterized using the laser light diffraction method, X-ray diffraction method and scanning electron microscopy. Sintered glassceramic material was characterized using the X-ray diffraction method, Archimedes principle, scanning electron and optical light microscopy and the Vickers hardness test. The glass-ceramic material obtained by sintering andesite basalt powder could be used for various industrial applications in the civil engineering, mechanical, chemical, and petrochemical industries, as well as for the making of containers to store nuclear waste.

Oxynitrides of cerium are expected to have many useful properties but have not been synthesized so far. We identified possible modifications of a not-yet-synthesized Ce3O3N compound, combining global search (GS) and data mining (DM) methods. Employing empirical potentials, structure candidates were obtained via global optimization on the energy landscape of Ce3O3N for different pressure values. Furthermore, additional feasible structure candidates were found using data mining of the ICSD database. The most promising structure candidates obtained were locally optimized at the ab initio level, and their E(V) curves were computed. The structure lowest in total energy, Ce3O3N-DM1, was found via local optimization starting from a data mining candidate and should be thermodynamically metastable up to high pressures.

The effect of laser (532 nm line of Verdi G) heating during the Raman measurements, on partial decomposition of Bi12SiO20 single crystal, was addressed in this study. The degree of decomposition directly depends on the power density and duration of the laser treatment, which are registered by the phonon Raman spectra. After laser treatment, AFM measurements register additional small spherical islands on the surface. Analysis performed on irradiated and unirradiated samples showed significant changes in transmission spectra, X-ray diffraction (XRD) pattern, Verdet constant, magneto-optical property, and absorption coefficient. The material obtained after laser irradiation can be described as specific nanocomposite consisting of bismuth oxide and silicon oxide-based nano-objects (dimensions below 15 nm in diameter), which are arranged in a matrix of Bi12SiO20.

In the present study, andesite basalt originated from the deposit site “Donje Jarinje”, Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070 and 1080°C, and afterwards the sintering duration was varied from 30 to 240min at the optimal sintering temperature of 1060°C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardness and fracture toughness complemented with X-ray diffraction, optical light microscopy, scanning electron microscopy and energy dispersive spectroscopy analysis. Phase transformations did not occur during processing in the investigated temperature range from 1040 to 1080°C. The obtained research results showed that 99.5% of relative density and the highest hardness and fracture toughness values of 6.7GPa and 2.2MPa•m1/2, respectively, were achieved for the andesite basalt sintered at 1060°C for 60min in the air. The results of the present study confirmed that the sintered andesite basalt can be used as a high-density ceramic material for various industrial applications.

Nanoemulsion technique based on Ouzo effect was applied for the fast and simple synthesis of Ag3PO4 at room temperature. X-ray powder diffraction analysis and Raman spectroscopy reviled that synthesized powder was single-phase. Using scanning electron microscopy analysis, it was found that the synthesized Ag3PO4 particles were near-spherical shape with an average diameter of 100 nm. The high value for the specific surface area of obtained powder was measured by Brunauer–Emmet–Teller method. Finally, the Ag3PO4 product was used as a photocatalyst for the photodegradation of crystal violet dye in an aqueous solution. Nanoemulsion strategy procedure provides a simple pathway to obtain a highly efficient single-phase Ag3PO4 photocatalyst.

Spider silk-maghemite (SS-gamma-Fe2O3) composite was obtained by simple and fast co-precipitation method at room temperature. The fibers were coated with maghemite nanoparticles with the average size of 25 nm. According to DTA, maghemite NPs contributed the thermal stability of the composite. Magnetic properties of as obtained composite were estimated. At room temperature, the system was is in a superparamagnetic state, while at temperature of 5 K the magnetic moments were blocked. This composite is seen as a novel hybrid material with superparamagnetic properties for possible applications in bioseparation, biosensors, magnetographic printing, magnetic screens, and magnetic filters as well as sensing/actuating components of MEMS.

Rare earth luminescent materials based on alkali metal oxides such as calcium aluminates have grabbed the attention due to their high luminescent efficiency, non-toxic and eco-friendly nature. Calcium aluminates as host materials for luminescent applications are extremely stable, suppressing the release of non-radiative energy resulting in the characteristic emission of rare earth luminescent centre. Moreover, calcium aluminates are inexpensive for their use as host material for luminescent applications. With texture and color giving the aesthetic contribution, Europium (Eu) doped single phase Mayenite may find potential applications in the design of energy efficient buildings when used as a coating material. Eu doped single phase Mayenite powders in varying concentrations (0%, 0.5%, 1%, and 1.5%) were prepared using self-propagating combustion synthesis method using metal nitrates and glycine as the fuel. The X-ray diffractograms confirmed the formation of single phase Mayenite with some of the Ca2+ ions getting replaced by Eu3+ ions. The photoluminescence emission spectra revealed 5D0 → 7F2 transition due to the crystal field effect and was characterized by the bright red luminescence. The doping of Eu resulted in a decrease of band gap from 4.8 ​eV for undoped Mayenite to 3.5 ​eV for 1.5% Eu doped Mayenite. The samples were found to exhibit excellent fluorescent properties under UV irradiation.

Supporting information of the article Metal-Like Thermal Conductivity Possessed By Atmosphere Assisted Synthesis Of Spark Plasma Sintered Mayenite (Ca12Al14O33).

In the last decade, an immense progress has been made in white LEDs, mainly due to the development of red-emitting phosphors. In this paper, we report on the synthesis of Eu3+ activated Y2MoO6 by a self-initiated and self-sustained method. The obtained powder was calcined at various temperatures in the 600–1400 °C range and examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL). The results revealed that all powders are single phase Y2MoO6:Eu3+, with particle size in the nanorange at lower treatment temperatures (600 and 800 °C) and in the microrange at higher calcination temperatures (1000–1400 °C). The obtained powders are promising materials for white light-emitting diodes as they can efficiently absorb energy in 324–425 nm region (near-UV to blue light region) and emit at 611 nm in the red region of the spectrum, while exhibiting high thermal and chemical stability.

There are no available data about direct burkeite formation on the geothermal waters pipelines in Europe. Data about accompanying minerals of burkeite are also scarce. This mineral has been found in the scale on pipelines of VG-2 and VG-3 boreholes at Vranjska Banja, Serbia. Geothermal waters from these boreholes have temperatures in the range of 103 and 105 °C which classifies them to the warmest waters in the continental Europe. Based on physicochemical and geochemical data, VG-2 and VG-3 geothermal waters can be classified as Na–Alk–SO4Cl type of waters. According to their temperatures, total hardness and pH values, these waters belong to hyperthermal, very soft and moderately alkaline. Calculated LSI (0.4 and 1.7) and RSI (6.5 and 4.8) values indicate their scale formation tendency. Results of the spectrometric scale examination from the pipe deposits provide a clear qualitative and quantitative burkeite characterization with its accompanying minerals. FTIR analysis points to the presence of carbonate (1766, 1458, 877 and 705 cm−1) and sulfate bands (1139, 1116 and 617 cm−1). Apart from the qualitative analysis, XRD also shows the burkeite mass part in the scale. VG-2 geothermal water contains about 50% of burkeite, which is associated with trona mineral (40%) and smaller amount of halite of about 10%. Burkeite is a dominant phase (> 60%) in VG-3 water, with the presence of a significant halite quantity (> 35%) and a minor calcite quantity (2%). © 2019, International Association for Mathematical Geosciences.

Surface modification of CeO2 nano-powder, synthesized by a self-propagating room temperature method with salicylate-type ligands (salicylic acid and 5-aminosalicylic acid) as well as catecholate-type ligands (catechol, 3,4-dihydroxybenzoic acid, caffeic acid and 2,3-dihydroxy naphthalene), induces the appearance of absorption in the visible spectral region due to the interfacial charge transfer (ICT) complex formation. Thorough characterization involving transmission electron microscopy, XRD analysis, and nitrogen adsorption-desorption isotherms, revealed that loosely agglomerated CeO2 particles of the size ranging from 2 to 4 nm have cubic fluorite structure and specific surface area of 140 m2/g. The attachment of salicylate- and catecholate-type of ligands to the surface of CeO2 powders leads to the formation of colored powders with tunable absorption in the visible spectral region. The density functional theory calculations with properly design model systems were performed to estimate the alignment of energy levels of various inorganic/organic hybrids. A reasonably good agreement between calculated values and experimental data was found. © 2019

Surface modification of CeO2 nano-powder, synthesized by a self-propagating room temperature method with salicylate-type ligands (salicylic acid and 5-aminosalicylic acid) as well as catecholate-type ligands (catechol, 3,4-dihydroxybenzoic acid, caffeic acid and 2,3-dihydroxy naphthalene), induces the appearance of absorption in the visible spectral region due to the interfacial charge transfer (ICT) complex formation. Thorough characterization involving transmission electron microscopy, XRD analysis, and nitrogen adsorption-desorption isotherms, revealed that loosely agglomerated CeO2 particles of the size ranging from 2 to 4 nm have cubic fluorite structure and specific surface area of 140 m2/g. The attachment of salicylate- and catecholate-type of ligands to the surface of CeO2 powders leads to the formation of colored powders with tunable absorption in the visible spectral region. The density functional theory calculations with properly design model systems were performed to estimate the alignment of energy levels of various inorganic/organic hybrids. A reasonably good agreement between calculated values and experimental data was found.

Cerium oxide nanoparticles (nCeO2) are biomaterials with numerous applications in biomedicine, fuel additives and electronics. Since their low stability in aqueous media limited their practical application, the aim of this study was to improve the suspension stability of nCeO2 by coating the particles. Glucose, monosaccharide, and levan and pullulan, microbial polysaccharides, were used as coating material. The coating was attempted under different synthesis conditions, by adding the carbohydrates during (direct coating) or after (subsequent coating) the synthesis of nCeO2. X-Ray diffraction analysis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization of nanoparticles’ powders. Measuring of hydrodynamic size, zeta potential and turbidity was used for the estimation of nanoparticles’ suspension stability in aqueous media. The success of subsequent coating with carbohydrates and the differences between coated nCeO2 have been proven with FT-IR spectra. Turbidity measurement showed the best stability of levan- and glucose-coated nCeO2 suspensions. It can be concluded that coating with carbohydrates improved the stability of the nCeO2 suspension by decreasing the size of aggregated particles. The obtained results open new horizons for further ecotoxicity investigation and nCeO2 application.

Cerium oxide nanoparticles (nCeO2) are nanomaterial with various applications in biomedicine, electronics and cosmetics. The aim of this research was to improve their low suspension stability by coating with carbohydrates - glucose, levan, and pullulan. The coating was performed at different temperatures and coating times, by adding the carbohydrates during or after the synthesis of nCeO2. Characterization of nanoparticles’ powders was performed by X-Ray diffraction analysis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Nanoparticles’ suspension stability was estimated by measuring of zeta potential, hydrodynamic size and turbidity. The difference among coated nCeO2 have been confirmed with FT-IR spectra. The results showed improved stability of the nCeO2 suspension and decreased size of aggregates after carbohydrate coating. Levan- and glucose-coated nCeO2 suspensions showed the best stability. The obtained nCeO2 were used for the investigation of their ecotoxicity on different plant species.

Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase) as well as magnesium hydroxide (Mg(OH)2, brucite) fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2) in the presence of the spider silk fibers, while magnesium hydroxidefibers were synthesized by hydration of MgO fibers at 50 °C, 70°C and 90 °C, for 48 and 96 h. According to Scanning electron microscopy (SEM), dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH)2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH)2 fibers was noticed to be covered with brucite in a form of plates. X-ray diffraction (XRD) analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained), while Mg(OH)2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature., Vlakna paukove mreže sakupljena od Pholcus phalangioides pauka korišćena su kao matrica za dobijanje vlakana magnezijum oksida (MgO, periklas) i magnezijum-hidroksida (Mg(OH)2, brucit). Vlakna magnezijum oksida jednostavno su dobijena termičkim razlaganjem soli magnezijuma (MgCl2) u prisustvu vlakana paukove mreže, dok su vlakna magnezijum hidroksida sintetisana hidratacijom MgO vlakana na temperaturama: 50, 70 i 90 °C u trajanju od 48 i 96 h. Na osnovu rezultata skenirajuće elektronske mikroskopije (SEM), veličina sintetisanih MgO vlakana bila je određena dimenzijama vlakana pauka, dok je za Mg(OH)2 vlakna prosečan dijametar rastao sa produženjem perioda hidratacije. Na površini Mg(OH)2 vlakana uočeni su tabličasti kristali brucita. Difrakcija X zraka (XRD) pokazala je da su vlakna periklasa jednofazna (dobijen je čist magnezijum-oksid), dok su brucitna vlakna bila dvofazna ili jednofazna, u zavisnosti od inkubacionog perioda i/ili teperature na kojoj je vršena inkubacija.

Hydroxyapatite was used as the inert matrix for in-situ immobilization of strontium (Sr) radioactive isotopes at room temperature. A nano-emulsification method was applied to synthesize Sr-substituted calcium hydroxyapatite (Ca1-xSrx)PO4)(6)(OH)(2). The concentration of incorporated Sr was in the range of 0 LT = x LT = 1. Immobilization of Sr was evaluated using a stable isotope instead of radioactive isotope. The effect of strontium concentration on the crystal structure was studied and the results have showed that in the whole concentration range, Sr forms solid solutions with the host hydroxyapatite crystal structure. Powders comprised of nanometre sized particles were obtained and their properties, such as crystallite and particle size, changes in lattice parameters as function of dopant content and thermal stability, were further examined. It was found that the crystal structure of obtained powders is thermally stable at high temperatures. No secondary phases were formed in as-prepared powders or during calcination. The results in this study showed that nano-emulsion strategy provides a simple pathway for synthesis of a single-phase Sr-substituted hydroxyapatite, which can be used for immobilization of Sr radioactive isotopes.

U ovoj doktorskoj disertaciji ispitane su mogućnosti dobijanja monetita (CaHPO4) i nanosferičnog karbonatno stroncijskog hidroksiapatita [Sr10(PO4)6(OH)(2-2x)(CO3)x ] bržim, jednostavnijim i ekonomski isplativijim postupcima sinteze od dosada korišćenih. Sinteza monetita (CaHPO4) urađena je korišćenjem tehnike mlevenja brušita (CaHPO4∙2H2O) u vibracionom mlinu pri čemu dolazi do njegove fazne transformacije. Ispitivan je uticaj dužine mlevenja na fazni sastav i mikrostrukturne parametre tretiranog materijala. Prikazan je i mehanizam fazne transformacije brušit - monetit pri kratkom vremenu mlevenja (ukupno 12,5 min.). Uočeno je da se monetit formira nakon 5,0 minuta mlevenja u vibracionom mlinu faznim prelazom brušit-monetit. Primenom metode rendgenske difrakcije na polikristalnim materijalima izučavan je fazni sastav i mikrostrukturni parametri sintetisanih i mlevenih kalcijum fosfatnih (CaP) materijala. Ramanska spektroskopija, kao komplementarna metoda rendgenskoj difrakcionoj analizi, upotrebljena je za ispitivanje početnog brušitnog materijala. Infracrvena spektroskopija sa Furijeovom transformacijom iskorišćena je za ispitivanje i praćenje toka promena faznog sastava tokom mlevenja. Adsorpciono-desorpciona metoda (BET) korišćena je za određivanje poroznosti materijala mlevenog 5,0 min, dok su morfološke karakteristike materijala i semikvantitativni sastav ispitane korišćenjem metodom skenirajuće elektronske mikroskopije sa energijsko disperzivnom analizom (SEM-EDS). Mezoporozni monetitski material dobijen je nakon 5,0 minuta mlevenja u vibracionom mlinu. Ovako dobijen material korišćen je za adsorpciju fosfatnog pesticida-malationa iz vodenog rastvora. Rezultati adsorpcije pokazali su da se malation može uspešno odstraniti iz vodenog rastvora korišćenjem monetita kao adsorbenta..., In this doctoral dissertation the main goal was to examine the possibilities for obtaining monetite (CaHPO4) and nanospheric strontium carbonate hydroxyapatite [Sr10(PO4)6(OH)(2-2x)(CO3)x ] materials by using faster, easier and cost-effective methods for synthesis. Monetite (CaHPO4) material was obtained by milling previously synthesized brushite (CaHPO4∙2H2O), in a vibratory mill resulting in its phase transformation occures. The effect of the different time periods of milling treatment on the phase composition and microstructural parameters of the treated material was also examined. The mechanism of phase transformation brushite-monetite during short time milling (12.5 minutes in total) was also shown. It was found that after 5.0 minutes of milling monetite phase starts to form, after brushite-monetite phase transition. The X-Ray powder diffraction (XRPD) method was used to investigate microstructural and phase properties of synthesized and milled calcium phosphate (CaP) samples. Raman spectroscopy, as a complementary method to XRPD analysis was used to confirm the purity of synthesized initial brushite material. Fourier transformation infra red spectroscopy (FTIR) was used for investigation and monitoring of the phase composition changes during milling treatment. The adsorption-desorption method (BET) was used to determine the porosity of the material milled for 5,0 min., whereas the morphological characteristics and semiquantitative analysis of obtained materials was observed using the method of scanning electron microscopy with energy dispersive analysis (SEM-EDS). Monetite material with mesoporous properties was obtained after 5,0 minutes of milling in a vibratory mill. This material was further applied as adsorbent for adsorption of phosphate-pesticides i.e. malathion from aqueous solution...

Nanometric-sized gadolinia (Gd2O3) powders were obtained by applying solid-state displacement reaction at room temperature and low temperature calcination. The XRD analysis revealed that the room temperature product was gadolinium hydroxide, Gd(OH)(3). In order to induce crystallization of Gd2O3, the subsequent calcination at 600 similar to 1200 degrees C of the room temperature reaction products was studied. Calculation of average crystallite size (D) as well as separation of the effect of crystallite size and strain of nanocrystals was performed on the basic of Williamson-Hall plots. The morphologies of powders calcined at different temperatures were followed by scanning electron microscopy. The pure cubic Gd2O3 phase was made at 600 degrees C which converted to monoclinic Gd2O3 phase between 1400 and 1600 degrees C. High density (96% of theoretical density) ceramic pellet free of any additives was obtained after pressureless sintering at 1600 degrees C for 4 h in air, using calcined powder at 600 degrees C. (C) 2017 Elsevier Ltd. All rights reserved.

Simple route was used for synthesis of nanostructured titania samples doped with 3 and 6 mol% of Cr3+ Titanium(IV)-isopropoxide and water were used as starting materials and as an agents for controlling hydrolysis and condensation reactions. The phase evolution of titania (TiO2) was followed by calcination at 400, 600 and 800 degrees C. The synthesized powders were examined by field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). Single-phase anatase was obtained at low temperature (400 degrees C) in all cases. The photocatalytic activity of TiO2 doped nanopowders was evaluated by the photocatalytic degradation of crystal violet in aqueous solution. The present study indicates that this simple synthesis method can be an effective route to produce efficient photoactive doped anatase nanopowders. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Titanium dioxide nanopowders, doped with different amounts of Fe3+ ions (0.3-5 mass%), were synthesized by acid-catalyzed sol-gel method in a non-aqueous medium. The obtained powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and determination of izoelectric points as well as particle diameters. Careful investigation of porous structure was provided by application of nitrogen adsorption-desorption method. Structure analysis showed that the obtained nanopowders exhibited the anatase crystal structure, independent of the amount of iron dopants. The presence of Fe3+ ions in anatase decreases the value of isoelectric point of undoped TiO2. Unlike crystal structure, porosity parameters are strongly affected by the amount of iron ions incorporated in TiO2 lattice. The mesoporosity of TiO2 can be successfully controlled by changing the amount of iron dopants. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The interaction between charge carriers and phonons is the primary mechanism through which charge carriers exchange energy with the crystal lattice. A proper understanding of the electron-phonon interaction is of great importance. We conducted a comprehensive investigation to examine the electron-phonon interaction in semiconductor crystals of Zn1-xCdxGeAs2 (0 ≤ x ≤ 1). For this objective, X-ray diffraction, far-infrared reflection, and Raman scattering studies were employed. In addition to the two primary phases, namely ZnGeAs2 and CdGeAs2, four component phases were also identified: ZnAs2, CdAs2, GeAs, and GeAs2. A spatially inhomogeneous distribution of charge carriers was detected, with the highest concentration in the vicinity of the formed GeAs. Analysis of the Far-infrared reflection spectrum of ZnGeAs2 (x = 0) revealed that plasmon-4 phonon interaction occurs, while in CdGeAs2 (x = 1), there is a plasmon-3 phonon interaction. All other samples have both of these interactions, according to their percentage in the composition. Raman measurements revealed that due to the influence of free charge carriers, there is an increase in the intensity of phonon modes, their displacement, or their splitting into two modes. The intensity and the way the electron-phonon interaction vary depending on the local concentration of free carriers, and it is the strongest in the areas around the formed GeAs. The obtained results and performed analyses revealed the existence of different phases in the material, inhomogeneous charge distribution, and electron-phonon interaction, which are essential properties of thermoelectric materials.