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Numerous methods have been utilized for molecular detection, including optical, calorimetric, acoustic, and techniques based on changes in electrical properties, such as metal oxide semiconductor sensors [1,2]. Recent research endeavors have led to a significant rise in sensitivity, detecting parts per billion (ppb) [3], but the challenges of selectivity and cross-sensing remain crucial areas of investigation. Developing a gas sensor with high selectivity to efficiently analyze multi-gas mixtures would be of great significance, with potential applications in various fields such as technology, environmental control, biology, and medicine. Quantum sensors are a promising new technology for the detection of gas mixtures. They offer a number of advantages over traditional methods, including high sensitivity, selectivity, and response time. In the presentation, we propose a new method based on the resonant interaction of dipole molecules with ac fields, in the presence of a dc electric and magnetic field that creates Zeeman and Stark splitting of molecular levels specific to certain molecules, ensuring selectivity [4]. In this talk, we present some preliminary experimental results obtained for the molecule NO on the use of quantum sensors for the detection of gas mixtures. Our results demonstrate the potential of quantum sensors for a variety of applications in gas sensing. We believe that quantum sensors have the potential to revolutionize the field of gas sensing. 1. X. Liu, et al. Sensors (Basel), 12 (2012) 9635–9665. 2. S. Lakkis, R. Younes, Y. Alayli, M. Sawan, Sensor Review, 34 (2014) 24–35. 3. J.-H. Lee, J.-Y. Kim, J.-H. Kim, S. S. Kim, Sensors (Basel), 19 (2019) 726. 4. Z. Branković, Y. Rostovtsev, Sci. Rep., 10 (2020) 1537.

Dyes released from textile industries present a big threat to the environment, and remediation of wastewaters became one of the major scientific challenges. In recent years, there has been a great need for catalysts that would oxidize pollutants under dark ambient conditions without the use of external stimulants like light, temperature, or additional chemicals such as O3, H2O2. Efficient work of these catalysts would significantly reduce the energy consumption. Among other materials, perovskite-type oxides with general formula ABO3 emerged as possible catalysts for dye degradation in the dark conditions. Lanthanum nickelates with single (LaNiO3) and layered perovskite structure (La4Ni3O10, La3Ni2O7, La2NiO4) showed good catalytic properties, due to the existence of nickel in two oxidation states (Ni2+ and Ni3+) and the oxygen non-stoichiometry in these materials [1]. This study presents structural, microstructural and catalytic properties of the LaNi1-xNbxO3-based (xNb = 0.000, 0,005 and 0,010; La-Ni-Nb-O) powders prepared by mechanical activation method. The XRD (X-Ray Diffraction) analysis revealed the existence of a multiphase oxide system, including layered structures of nickelates Lan+1NinO3n+1 (n = 3, 2, 1, 0) and NiO phase in all La-Ni-Nb-O-based powders. Also, the HRTEM (High Resolution Transmission Electron Microscopy) analysis confirmed the presence of structural polytypes in these powders. The catalytic properties of La-Ni-Nb-O-based powders were investigated by degradation of the anionic azo dye, Reactive Orange 16 (RO16), under dark ambient conditions at different pH values (3, 6.5, 9.5 and 11) and temperature of 20 °C. The best catalytic efficiency in the degradation of RO16 dye showed the sample with x(Nb) = 0.010 in acidic solution, where the residual of RO16 dye was about 4.5 % after 330 minutes. The reusability test for this powder in degradation process of RO16 dye showed that the sample with x(Nb) = 0.010 retained its catalytic activity during t

Ovo tehničko rešenje je na 11. redovnoj sednici Matičnog naučnog odbora za biotehnologiju i poljoprivredu, održanoj 23.11.2022 godine, svrstano u kategoriju M82.

Intergranular and intragranular cracks that usually form during sintering of yttrium manganite (YMnO3) ceramic samples hinder the densification process of this ceramic and deteriorate its magnetic and ferroelectric properties. To overcome this problem, mechanochemically synthesized YMnO3 powder was sintered using two different processes: Conventional Sintering (CS) and Pulsed Electric Current Sintering (PECS). All samples were characterized by XRD, SEM and FESEM and their magnetic and ferroelectric properties were investigated. Apart from their phase composition, conventionally sintered ceramic samples showed cracks throughout their whole volume, reaching a maximum relative density of 85 %. However, it was found that PECS process could significantly reduce the presence of cracks within samples whose relative density reached 99.8 %.

Yttrium manganite (YMnO3) is widely investigated multiferroic material with potential use in many technological applications. In this paper, we report on the preparation and characterization of multiferroic hexagonal YMnO3 ceramics obtained by chemical synthesis route. Precursor powders were prepared by the polymerizable complex method from citrate precursors. After calcination at 900 degrees C the powders contained mixture of Y-Mn-O phases which were further sintered at different temperatures. XRD analysis revealed that sintering at 1400 degrees C resulted in the formation of pure hexagonal YMnO3. Density of the obtained ceramics was 96 %TD. The ceramic samples proved to have multiferroic properties - they are antiferromagnetic below 42 K with linear dependence of magnetization as a function of applied magnetic field. The ferroelectric measurements performed at room temperature showed remanent polarization of 0.21 mu C/cm(2) and the coercive field of 6.0 kV/cm for the YMnO3 sample sintered at 1400 degrees C. The magnetization curves measured at 2 and 5 K for the powder samples calcined at 900 degrees C and ceramic samples sintered at 1300 degrees C exhibited a hysteresis loop due to a small concentration of Mn3O4 in the samples.

Mesoporous TiO2 films with spherical architectures and promising performance in dye-sensitized solar cells (DSSCs) were prepared. The morphology of the films was investigated by scanning electron microscopy. Transmission electron microscopy analysis of the spheres disclosed the elongated shape of sub-20 nm primary particles, while BET analysis revealed their high surface area of 135m2/g. Anatase presence was observed in the films based on X-ray diffractometry, selected-area electron diffraction analysis and Raman spectroscopy analyses. Increased light scattering of the spheres in visible region was observed by UV-VIS-NIR spectroscopy. Photovoltaic performance of the operating N719-sensitized cells was tested using electrochemical impedance spectroscopy and current density-voltage (J-V) curves under simulated AM1.5 spectrum. The 0.25 cm2 cells exhibited photo-to-electric power efficiency of 4.9%, which is among noteworthy values for DSSCs with similar photoanodic structures

Multiferroic materials simultaneously possess two or more ferroic orders, and enable a coupling interaction between them. Multiferroic bismuth manganite is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. Unfortunately, preparation of BiMnO3 is not possible by conventional solid state reaction and BiMnO3 has been synthesized from the mixture of oxides only at high pressures (>40 kbar). The aim of this work was to synthesize BiMnO3 (BMO) without additional heating or application of high pressures. Nanocrystalline single-phased BMnO3 was prepared for the first time by mechanochemical synthesis directly from the highly activated constituent oxides, Bi2O3 and Mn2O3, in a planetary ball mill. The obtained materials were characterized by X-ray diffraction, SEM with EDS analysis, HRTEM and magnetization measurements. All the samples were found to be tetragonal perovskite with P4mm crystallographic group. The broad maxima reflections of BMO samples can be ascribed to an amorphous/disordered phase. HRTEM micrographs give clear evidence of core-shell structure with amorphous shell around the nanocrystalline BMO particles. The magnetic hysteresis behavior is similar to that of a soft ferromagnet. The magnetic properties of the obtained BMO powders were found to change as a function of milling time in a manner consistent with the variation in the nanocomposite microstructure.

Multiferroic yttrium manganite (YMnO3) is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. In this work single-phased YMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. The YMnO3 can be formed directly from the highly activated constituent oxides, Y2O3 and Mn2O3, after 60 min of milling time and subsequently grows during prolonged milling. The cumulative energy introduced into the system during milling for 60 min was 86 kJ/g. X-ray analysis indicates that the as-prepared samples crystallize majority with hexagonal (P63cm) and minorly with orthorhombic (Pnma) YMnO3 structure. The morphology, structure and chemical composition of the powder were investigated by SEM with EDS and TEM. The magnetic properties of the obtained YMnO3 powders were found to change as a function of milling time in a manner consistent with the variation in the nanocomposite microstructure.

Bi1-xGdxFeO3 (x = 0.01; 0.05; 0.075; 0.09; 0.10; 0.20; 0.30) powders were synthesized by hydro-evaporation method. The optimization of sintering conditions indicated that temperature of 870 °C and time of 6 hours (after pressing at 9 t/cm2) provided the densest ceramics samples (up to 88 % of theoretical density) and the lowest amount of secondary phases ( 5.5 wt%). The increase of gadolinium content resulted in polar-to-nonpolar (R3c  Pnma) structural phase transition at about x = 0.10, which was reflected on deterioration of ferroelectric property. Structural analysis indicated decrease of unit cell volume with the increase of x, but the (Bi,Gd)–Fe distance did not exhibit regularity in change. The bismuth ferrite ceramics samples doped with x = 0.075 and x = 0.09 of gadolinium showed the greatest lattice distortion along the [111] axis. These samples also exhibited larger values of remnant electric polarization and less leakage processes than the pure bismuth ferrite ceramics samples. Magnetic behavior of Bi1-xGdxFeO3 samples revealed that the weak ferromagnetic moment strengthened with increase of the gadolinium content.

U okviru ove doktorske disertacije ispitivan je uticaj parametara mehanohemijske i hemijske sinteze na strukturu i svojstva prahova i keramičkih uzoraka itrijum- -manganita (YMnO3, YMO).Smeša prahova Y2O3 i Mn2O3 mlevena je u planetarnom mlinu tokom vremenskih perioda od 60 – 720 min. Rendgenska analiza dobijenih prahova pokazala je da su tokom mlevenja od 240, 360 i 720 min dobijeni jednofazni pahovi rombičnog YMnO3 (o-YMO). Primarne čestice u prahovima su ispod 100 nm, a produžavanje vremena mlevenja dovodi do aglomeracije. Magnetna svojstva ukazuju da su prahovi u osnovi antiferomagnetični, uz delimično narušeno uređenje spinova prisustvom Mn4+-jona..., Within this doctoral dissertation, the influence of mechanochemical and chemical synthesis parameters on the structure and properties of yttrium manganite (YMnO3, YMO) powders and ceramics was investigated. Mixture of Y2O3 and Mn2O3 was milled in a planetary ball mill for periods of 60 – 720 min. X-ray analysis of the resulting powders showed that single-phased orthorhombic YMnO3 (o-YMO) powders were obtained for milling periods of 240, 360 and 720 min. The size of primary particles in the powders was below 100 nm, while a prolongation of the milling time led to agglomeration. The magnetic properties indicated that the powders were basically antiferromagnetic with partially disordered spins by the presence of Mn4+ ions...

Background In the Unites States of America, near 10% of women in their lifetime will be hospitalized and operated on because of ovarian mass suspected for an ovarian cancer. Diagnostic options are limited for a gynecologist to detect ovarian cancer in its early stages. As a result, around 70% of ovarian cancer cases are diagnosed in the advanced disease stages, when 5-year survival is sometimes less than 30%. The prognosis is better, if the surgery is performed by gynecological oncologist in specialized cancer care centers. In that direction, a proper triage is of pivotal importance for an optimal surgical treatment and consequently a better survival. Objectives To find out the validity of tumor marker HE4 in diagnosis of ovarian cancer and compare it with the validities of CA125 and ultrasound. To find out the validity of our Algorithm for prediction of ovarian malignancy (APOM) and compare it with validities of biochemical tumor markers previously mentioned, algorithms, ultrasound scores and doppler indices (ROMA, CPH-I, RMI, MI, PI and RI). Material and methods Prospective clinical trial included 200 cases in the study group with detected ovarian tumor by ultrasound. Inclusion criteria were: women 18 years of age and older with an ovarian mass, scheduled for surgical intervention. Exclusion criteria: pregnant women, women during lactation, women with prior unilateral and/or bilateral oophorectomy, women with history of current or past malignancy and advanced chronic diseases. The control group represented by healthy women included 100 women with normal ultrasound scan of the ovaries. Ultrasonography was performed using GE Voluson Е8 ultrasound machine with a transvaginal ultrasound probe RIC5-9D, 4-9 MHz (ovarian tumor morphology and doppler of the tumor vasculature). Afterward, patients were scheduled for vein blood sampling for HE4 and CA125 determination. After the surgery and histology verification of the operative material, patients were grouped according to

BiFeO3 powders were synthesized by sonochemically assisted hydrothermal and hydro-evaporation methods. The X-ray diffraction confirmed the presence of secondary phases, Bi25FeO39 and Bi2Fe4O9, in as prepared BiFeO3 powders. Optimization of sintering conditions indicated that temperature of 800 degrees C and time of 2 h after pressing at 9 t/cm(2) provided ceramics samples with"the highest density (up to 96% of theoretical density) and the lowest content of secondary phases. Ferroelectric and magnetic characterization was performed on two selected ceramics samples with the highest densities. Ceramics obtained from the powder synthesized by the hydrothermal method showed greater lattice distortion along [1 1 1] axis and smaller grains, which resulted in larger values of electric polarization at room temperature. It also exhibited less Fe(3d)-O(2p) orbital overlapping due to a larger Fe-O-Fe bond angle, causing lower antiferromagnetic ordering and weak ferromagnetic behavior at low temperatures.

BiFeO3 powders were synthesized by sonochemically assisted hydrothermal and hydro-evaporation methods. The X-ray diffraction confirmed the presence of secondary phases, Bi25FeO39 and Bi2Fe4O9, in as prepared BiFeO3 powders. Optimization of sintering conditions indicated that temperature of 800 °C and time of 2 h after pressing at 9 t/cm2 provided ceramics samples with the highest density (up to 96% of theoretical density) and the lowest content of secondary phases. Ferroelectric and magnetic characterization was performed on two selected ceramics samples with the highest densities. Ceramics obtained from the powder synthesized by the hydrothermal method showed greater lattice distortion along [1 1 1] axis and smaller grains, which resulted in larger values of electric polarization at room temperature. It also exhibited less Fe(3d)–O(2p) orbital overlapping due to a larger FeOFe bond angle, causing lower antiferromagnetic ordering and weak ferromagnetic behavior at low temperatures.

Bismuth ferrite, BiFeO3 (BFO), powder was synthesized by hydrothermal method from Bi(NO3)(3)center dot 5H(2)O and Fe(NO3)(3)center dot 9H(2)O as precursors. The synthesized powder was further sintered using spark plasma sintering (SPS). The sintering conditions were optimized in order to achieve high density, minimal amount of secondary phases and improved ferroelectric andmagnetic properties. The optimal structure and properties were achieved after spark plasma sintering at 630 degrees C for 20min, under uniaxial pressure of 90MPa. The composition, microstructure, ferroelectric and magnetic properties of the SPS samples were characterized and compared to those of conventionally sintered ceramics obtained from the same powder. Although the samples sintered using conventional method showed slightly lower amount of secondary phases, the spark plasma sintered samples exhibited favourable microstructure and better ferroelectric properties.

Previously synthesized nanocrystalline ZnO doped with cobalt and manganese, Bi2O3 and Sb2O3 were the precursors for high voltage varistors preparation. Varistor ceramics were sintered at 750 degrees C, 770 degrees C or 900 degrees C for 1 h. An amount of 30 mass% of secondary phases and sintering temperature of 770 degrees C were found to be optimal for obtaining varistor with prominent properties. Achieved density was 97% of the theoretical value. Post-sintering phase composition included ZnO, gamma-Bi2O3 and pyrochlore-type with Zn2Bi3Sb3O14 nominal formula. Fine grained microstructure was accompanied with good phase distribution and excellent electrical characteristics: extraordinary high breakdown field of 3200 V mm(-1), high nonlinearity coefficients of 71 and 51 in 0.1-1 and 1-10 mA cm(-2) current density ranges, respectively, and low leakage current of 7.7 mu A cm(-2).

In this work single phase hexagonal YMnO3 powders were prepared starting from Y(CH3COO)(3)center dot xH(2)O, Mn(CH3COO)(2)center dot 4H(2)O, KMnO4 and KOH using methods of conventional (280 degrees C for 6 h) or microwave assisted hydrothermal synthesis (200 degrees C for 2 h) followed by calcination at 1200 degrees C for 2 h. According to FESEM analysis the calcined powders consisted of submicronic YMnO3 particles, which were uniform in shape and size. Ceramic samples were obtained by sintering the as-synthesized powders at 1400 degrees C for 2 h. XRD analysis confirmed the presence of the single phase hexagonal YMnO3. SEM analysis showed a dense and homogeneous microstructure with typical inter- and intra-grain cracks. Magnetic measurements indicated ferrimagnetic properties that were explained by non-stoichiometry of the obtained compound and an excess of manganese that was confirmed by ICP analysis.

Introduction: According to the frequency of malignant tumours in the world, ovarian carcinoma takes the eighth place; it is also the fifth most frequent tumour in women and the fourth cause of cancer death in women. In early discovering and treatment of ovarian carcinoma, before it expends out of the primary localisation, the five-year relative survival rate is 92%. Unfortunately, only 15% of all ovarian carcinomas are discovered in the early stage. It has been noticed that the survival rate is higher in women under the age of 65 than in the older ones and it varies depending on the morphological type of ovarian carcinoma, patient’s over-all health condition and the stage of the disease diffusion at the time of setting the diagnosis. The exact cause of ovarian carcinoma occurrence is still unknown, but many risk factors are related to the occurrence of this malignoma. The aim of this research was to analyze the clinical and pathological characteristics of ovarian carcinoma, as well as to determine Nanog, Sox2, Oct3/4, Sox4, CD44. CD117, Ezh2 and Stat3 expressions in paraffin sections of ovarian carcinoma and to compare the Nanog, Sox2, Oct3/4, Sox4, CD44, Ezh2 and Stat3 expressions with the clinical and pathological characteristics of ovarian carcinoma. Methods: During the research, the immunohistochemical method was applied. Paraffin sections of the tissue of ovarian carcinoma 5μm thick were used. Conclusion: Unfavourable clinical course of ovarian carcinoma was related to the positive Nanog, Sox2 and Oct3/4 expression, as well as with the absence or low expression of Sox4, CD117 and CD44, while the loss of Ezh2 and Stat3 expressions in ovarian carcinoma, indicated significantly longer survival.

Nanostructured single layered (pure TiO2 , pure α-Fe2O3 and mixed Fe2O3 /TiO2 with two different oxide ratios, 2 : 3 and 3 : 2) and double layered (TiO2 layer over a Fe2O3 layer) thick films have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100 °C and sintered at 650 °C/60 minutes. Structural, morphological and optical studies have been carried out using XRD, SEM analyses and UV/Vis spectroscopy. The prepared pure and mixed Fe2O3 /TiO2 thick films had a homogenous nanostructure without secondary phases. Indirect band gaps were determined from the measured transmission spectra and the obtained values are in the range of literature data. [Projekat Ministarstva nauke Republike Srbije, br. III45007]

Cink-oksid je poluprovodni materijal koji je zbog svojih specifičnih fizičkih i hemijskih svojstava (širok energijski procep, hemijska i fotohemijska stabilnost, optička propustljivost, piezoelektricitet, netoksičnost, antibakterijska svojstva) našao primenu u izradi optoelektronskih uređaja, uređaja na bazi površinskih akustičnih talasa, emitera polja, piezoelektričnih uređaja, propustljivih provodnih materijala, solarnih ćelija, kozmetičkih preparata i slično. U okviru ove doktorske disertacije detaljno je proučen uticaj uslova sol-gel sinteze modifikovanim Španhelovim postupkom i sinteze solvotermalnim postupkom na strukturna i mikrostrukturna svojstva dobijenih prahova ZnO. Ispitivan je uticaj pHvrednosti u modifikovanom Španhelovom postupku, kao i temperature, vremena trajanja i pH-vrednosti koloidnih prekursora primenjenih u solvotermalnoj sintezi na veličinu i morfologiju čestica praha ZnO na nano- i mikroskali. U karakterizaciji prahova korišćene su: rendgenska strukturna analiza, termijska analiza, skenirajuća i transmisiona elektronska mikroskopija, ramanska i infracrvena spektroskopija. Pokazano je da su prahovi dobijeni sol-gel sintezom višefazni i da osim ZnO sadrže cink-hidroksid-acetate. Ustanovljeno je da su kod takvih prahova nanočestice ZnO (dm ≈ 4 nm) sa jednakim orijentacijama samouređene u monokristalne domene. Prahovi dobijeni solvotermalnim postupkom predstavljaju fazno čist ZnO. Njihova morfologija pri konstantnoj temperaturi i vremenu sinteze (200 °C, 2 h) za pH-vrednosti prekursora u intervalu od 8 do 12 menja se od pravilnih heksagonalnih prizmi do zaobljenih nanočestica. Pokazano je da produžavanje vremena sinteze pri konstantnoj temperaturi (200 °C) i pH-vrednosti (8) uslovljava promenu oblika čestica od heksagonalnih ka štapićastim, submikronske veličine, uključujući i formiranje mezokristalnih čestica ZnO. Prah čije čestice pokazuju najveći stepen homogenosti po veličini i obliku sintetisan je iz slabo kiselog koloidnog prekursora (pH, Zinc oxide is a semiconductor material, which has been found useful in many applications, such as optoelectronic devices, surface acoustic wave devices, field emitters, piezoelectric devices, transparent conducting materials, sollar cells, cosmetics etc., due to its interesting properties, especially wide band gap, chemical and photochemical stability, optical transparency, piezoelectricity, nontoxicity, antibacterial and UV-protection properties. In this work, an influence of sol-gel (modified Spanhel method) and solvothermal synthetic conditions on structural and microstructural properties of ZnO powders was studied in detail. Precisely, the effect of pH value in modified Spanhel procedure, as well as temperature, time and pH value in solvothermal syntheses, on particle size and morphology was considered. The prepared powders were characterized by X-ray Diffraction Analysis, Thermal Analysis, Scanning and Transmission Electron Microscopy, Raman and Infrared Spectroscopy. The results showed that the powders obtained from sol-gel process are multiphase systems containing ZnO and zinc hydroxide acetates. These powders consist of ZnO nanoparticles (dm ≈ 4 nm) with the same orientation, which were self-assembled into single crystal domains. The powders from solvothermal syntheses are phase-pure ZnO. The morphology of these particles obtained at 200 °C, during 2 h with pH values in the range 8 – – 12, changes from regular, hexagonal prisms to rounded nanoparticles. At 200 °C and pH = 8, the extending of reaction time results in changing of particle shape from hexagonal prisms to rods of submicron scale, including mesocrystal particles. The powder synthesized from slightly acidic precursor (pH = 6) at 200 °C, during 6 h revealed the highest homogeneity of particles shape and size. The most probable growth mechanisms of particles at different reaction conditions were proposed. It was shown that it is completely possible to control morphology and size of ZnO particles by a

Thick films of nanostructured pure TiO2, -Fe2O3, Fe2O3/TiO2 (ratio 2:3 and 3:2) and a hetero-junction in the form of a TiO2 layer over a Fe2O3 layer have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100oC and sintered at 650oC/60 minutes. Structural, morphological and optical studies have been carried out using XRD, SEM, EDS analysis and UV/Vis spectroscopy. Fe2O3/TiO2 thick films had a homogenous nanostructure and no new compounds were formed. Indirect band gaps were determined from the measured transmission spectra.

A powder mixture of Bi2O3 and Fe2O3 was mechanically treated in a planetary ball mill in an air from 30 to 720 minutes. It was shown that the mechanochemical formation of BiFeO3 (BFO) phase was initiated after 60 min and its amount increased gradually with increasing milling time. A detailed XRPD structural analysis is realized by Rietveld's structure refinement method. The resulting lattice parameters, relative phase abundances, crystallite sizes and crystal lattice microstrains were determined as a function of milling time. Microstructural analysis showed a little difference in morphology of obtained powders. The primary particles, irregular in shape and smaller than 400 nm are observed clearly, although they have assembled together to form agglomerates with varying size and morphology. Dense BFO ceramics were prepared by conventional solid-state reaction at the temperature of 810oC for 1h followed immediately by quenching process.

Yttrium manganite (YMnO3) is a multiferroic material, which means that it exhibits both ferromagnetic and ferroelectric properties, so making it interesting for a variety of technological applications. In this work, single-phase YMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. The YMnO3 was formed directly from the highly activated constituent oxides, Y2O3 and Mn2O3, after 60 min of milling time. During prolonged milling, the growth of the particles occurred. The cumulative energy introduced into the system during milling for 60 min was 86 kJ/g. The X-ray powder-diffraction analysis indicates that the as-prepared samples crystallize with an orthorhombic (Pnma) YMnO3 structure. The morphology and chemical composition of the powder were investigated by SEM and FESEM. The magnetic properties of the obtained YMnO3 powders were found to change as a function of the milling time in a manner consistent with the variation in the nanocomposite microstructure.

Nanostructured single layered (pure TiO2, pure alpha-Fe2O3 and mixed Fe2O3/TiO2 with two different oxide ratios, 2 : 3 and 3 : 2) and double layered (TiO2 layer over a Fe2O3 layer) thick films have been fabricated by screen printing technology on a glass substrate. The pastes used for film preparation were obtained by adding an organic vehicle to the oxide powders together with a small percentage of binding glass frit. Samples were dried up to 100 degrees C and sintered at 650 degrees C/60 minutes. Structural, morphological and optical studies have been carried out using XRD, SEM analyses and UV/Vis spectroscopy. The prepared pure and mixed Fe2O3/TiO2 thick films had a homogenous nanostructure without secondary phases. Indirect band gaps were determined from the measured transmission spectra and the obtained values are in the range of literature data.

Titanium(IV) oxide in the form of anatase has proven to be the best choice for photoanodic material in dye-sensitized solar cells (DSCs). The aim of the work was to study the influence of binder molecular weight on the morphology of deposited films, and consequently, DSC parameters. For this study, five different TiO2 tape casting slips were prepared from commercially available nanoanatase powder and polyethylene glycol (PEG) as a binder. The process of drying and sintering was carefully designed, so that the organic template was slowly decomposed, leaving favorable crack-free, porous structure. It was found that there is an optimal region of binder molecular weight for obtaining homogeneous, non-agglomerated and porous microstructure which is a necessary condition for application of TiO2 films in DSCs.

Multiferroic bismuth manganite (BiMnO3) is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. Unfortunately, preparation of BiMnO3 is not possible by a conventional solid-state reaction and it can form only from mixture of oxides at high pressures (>40 kbar). In this work single-phased BiMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. A mixture of Bi2O3 and Mn2O3 was intensively milled in air atmosphere, using stainless steel vials and balls. According to analysis of XPRD results BiMnO3 obtained after milling for 240 min has a tetragonal structure with lattice parameters a = 3.9230 angstrom, c = 3.920 angstrom and a crystallite size of 16.8 nm. The cumulative energy introduced into the system during milling for 240 min was 401 kJ/g. It was found that the obtained powders were agglomerated. Corresponding agglomeration factors were calculated from the results of BET and particle size distribution analysis.

In this article the solid state reaction of BaTiO3 formation from a mechanically activated BaCO3-TiO2 system has been investigated. An equimolar mixture of BaCO3 and TiO2 powders was activated in a planetary ball mill in a continual regime for 0, 30 and 90 min, pressed and thermally treated up to 1200°C. The efect of the milling and firing regime on the phase formation was investigated by the X-ray diffraction (XRD) method and differential thermal analysis (DTA). Deconvolution of the experimental DTA curve corresponding to the BaTiO3 synthesis process has been performed. The influence of the activation time on the change of characteristic temperature for each elementary step in the complete solid-state reaction of BaTiO3 formation, was analyzed. These results were correlated with the ones obtained by SEM characterization and by XRD analysis.

U ovome radu je analiziran uticaj mehaničke aktivacije sistema BaCO3- TiO2 na formiranje BaTiO3. Ekvimolarne smeše praha BaCO3 i TiO2 su aktivirane u planetarnom mlinu u kontinualnom režimu tokom 0, 30 i 90 min. Uzorci su zatim presovani i termički tretirani do 1200oC. Efekat mlevenja i zagrevanja na promene faza je analiziran primenom rendgenske fazne analize i diferencijalne termijske analize. Izvršena je dekonvolucija eksperimentalno dobijene DTA krive koja odgovara procesu sinteze BaTiO3, kao i analiza uticaja vremena aktivacije na promene karakteristične temperature za svaki pojedinačni elementarni proces tokom sinteze barijum titanata. Ovi rezultati su korelisani sa rezultatima dobijenim SEM i XRD analizom., In this article the solid state reaction of BaTiO3 formation from a mechanically activated BaCO3-TiO2 system has been investigated. An equimolar mixture of BaCO3 and TiO2 powders was activated in a planetary ball mill in a continual regime for 0, 30 and 90 min, pressed and thermally treated up to 1200°C. The effect of the milling and firing regime on the phase formation was investigated by the X-ray diffraction (XRD) method and differential thermal analysis (DTA). Deconvolution of the experimental DTA curve corresponding to the BaTiO3 synthesis process has been performed. The influence of the activation time on the change of characteristic temperature for each elementary step in the complete solid-state reaction of BaTiO3 formation, was analyzed. These results were correlated with the ones obtained by SEM characterization and by XRD analysis.

In this article the solid state reaction of BaTiO3 formation from a mechanically activated BaCO3-TiO2 system has been investigated. An equimolar mixture of BaCO3 and TiO2 powders was activated in a planetary ball mill in a continual regime for 0, 30 and 90 min, pressed and thermally treated up to 1200 degrees C. The eject of the milling and firing regime on the phase formation was investigated by the X-ray diffraction (XRD) method and differential thermal analysis (DTA). Deconvolution of the experimental DTA curve corresponding to the BaTiO3 synthesis process has been performed. The influence of the activation time on the change of characteristic temperature for each elementary step in the complete solid-state reaction of BaTiO3 formation, was analyzed. These results were correlated with the ones obtained by SEM characterization and by XRD analysis.

The common nitrates precursor solution leading to the Y3Al5O12:Ce3+ (YAG:Ce) composition with 2 at.% of cerium, is ultrasonically atomised and introduced into the tubular flow reactor at 320 degrees C. Having in mind that extremely high heating rates and short residence time are associated with spray pyrolysis, the low temperature regime is used for aerosol decomposition for the production of segregation-free precursor powder that is additionally heated at 900 and 1000 degrees C (2-6h) for the purpose to determine the phase evolution. Formation of uniform and submicron-sized spherical particles with nano-clustered inner structure is proved by different analysing techniques (X-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopy). The effect of processing parameters and post-annealing treatment is discussed from the viewpoint of the targeted garnet phase formation.

A mixture of starting ZnO and Cr2O3 powders in equimolar quantities was mechanically activated by grinding using a high energy vibro-mil I for 0, 40 and 80 min. The spinet ZnCr2O4 was prepared from activated mixtures by a conventional solid-state reaction at the temperature of 900 degrees C during 240 min. Raman scattering (RS) and Far-infrared (IR) spectroscopy were applied to study the local structure of zinc chromium oxide spinels. We report on an analysis of the vibrational spectra of the spinet ZnCr2O4 structure using both the classical factor-group theory (O-h(7) spectroscopic symmetry) and a local environmental model. The structural modifications were studied on the basis of vibrations of ZnO4 tetrahedral and CrO6 octahedral units building the crystal lattice. The RS and IR line intensities and positions remained in good agreement with the Fd3m space group. The broadness of IR and Raman bands and the fact that more vibration modes than expected were observed, may be attributed to certain disorder in the crystal symmetry of cubic spinet ZnCr2O4. Formation of the defect spinel structure can be assigned to mechanical activation of the starting oxide mixture.