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Snow samples were collected near crossroads in Novi Sad, Serbia, during December 2009 to assess metal concentrations (Ca, K, Zn, Fe, Cu, Mn, Al, Pb and Na), fine particle distribution and pH value. The filtered samples of melted snow were analysed, with a focus on particles smaller than a few mu m. The most common values of the frequency number distribution curve were either in the range of 0.05-0.07 mu m or one order of magnitude higher (mu m). At examined locations metal concentrations varied from 0.0004 mg L-1 for Pb to 18.9 mg L-1 for Na. Besides Na, which mostly originated from de-icing salt, Ca is found to be the most abundant element in snow indicating the dominant influence of natural factors on snow chemistry. No significant difference was found in concentration of the elements at locations near crossroads with either low or high traffic volume, except for Na and Zn. To investigate how metals were related a correlation analysis was done for the concentrations of metals and with respect to the particle size distribution parameters and pH values. The major influence on the fine particle volume (mass) was concluded to be due to the elements from anthropogenic sources. This conclusion was based on the significant positive correlation between Fe, Zn and Al and the fine particle volume based distribution parameters.

У овој докторској дисертацији је испитано пет аморфних легура на бази гвожђа, различитог хемијског састава, са циљем да се код ових легура механизам и кинетика кристализације појединачних фаза разјасне и повежу са променама микроструктуре и морфологије, које наступају при загревању. Узорци свих испитиваних аморфних легура су добијени методом брзог хлађења на ротирајућем диску. Њихов хемијски састав у ат.% се може представити формулама Fe73,5Cu1Nb3Si15,5B7, Fe75Ni2Si8B13C2, Fe79,8Ni1,5Si5,2B13C0,5, Fe81B13Si4C2 и Fe40Ni40P14B6. Применом инструменталних структурних метода, XRD, Мезбауерове спектроскопије и електронске дифракције, идентификоване су кристалне фазе које настају загревањем и одређене су њихове количине, за сваку од легура. Рендгеноструктурном анализом нађени су микроструктурни параметри различитих фаза и праћене њихове промене услед изотермског загревања. TEM снимци узорака легура који су загревани на највишим температурама показују да су зрна различитих кристалних фаза величина од неколико десетина до неколико стотина нанометара и неправилних облика, при чему долази до срастања суседних зрна, на шта су указали и SEM снимци. Морфологија узорака загреваних неизотермски мења се при промени брзине загревања и максималне температуре до које се врши загревање, односно зависи од термичке историје узорака, што је утврђено методама SEM и AFM. У циљу испитивања термичке стабилности и процеса термичке стабилизације аморфних легура, примењена је метода диференцијалне скенирајуће калориметрије. Сложени кристализациони пикови разложени су до појединачних ступњева одговарајућим математичким поступком, при чему је примена изоконверзионих метода показала да пикови добијени разлагањем одговарају процесима који се одвијају у једном ступњу. Појединачни ступњеви су идентификовани у корелацији са фазним дијаграмима и уоченим..., In this dissertation, five iron-based amorphous alloys with different chemical compositions were examined to clarify the crystallization mechanism and kinetics corresponding to the formation of individual phases, and to correlate these properties with the changes in microstructure and morphology, which occur during heating. All of the examined alloy samples were prepared by using the melt-spinning method. Their chemical compositions can be represented as follows (at.%): Fe73,5Cu1Nb3Si15,5B7, Fe75Ni2Si8B13C2, Fe79,8Ni1,5Si5,2B13C0,5, Fe81B13Si4C2, and Fe40Ni40P14B6. Using structural characterization techniques including XRD, Mössbauer spectroscopy and electron diffraction, the crystalline phases formed during heating were identified and their quantities were determined for each of the alloys. XRD analysis yielded values of microstructural parameters of individual phases, and their changes induced by isothermal heating were monitored. TEM images of the alloy samples heated at the highest temperatures showed irregular-shaped grains of different crystalline phases ranging in size from several tens to several hundreds of nanometers, with visible coalescence of neighbouring grains, which was observed in SEM measurements as well. Morphology of non-isothermally treated samples changed with the heating rate and the maximum heating temperature, that is, it depends on the thermal history of the sample, which was observed using SEM and AFM methods. With a view to examining thermal stability of the amorphous alloys and thermal stabilization processes, differential scanning calorimetry was applied. Complex crystallization peaks were deconvoluted into individual steps by using appropriate mathematical procedure, while the application of isoconversional methods showed that the peaks obtained by deconvolution correspond to single-step processes. Individual crystallization steps were identified by correlating deconvoluted data with the phase composition diagrams and the observed micr

Thermal degradation of ternary transition metal complex containing tetraanion of pyromellitic acid, pyr, and ethylenediamine, en, [Ni-2(en)(2)(H2O)(6)(pyr)]center dot 4H(2)O, 1, was investigated under non-isothermal conditions. The mechanism of thermal degradation, which occurs in three steps, was clarified by TG/DSC measurements in conjunction with FT-IR spectroscopy and XRPD analysis. The complexity of all degradation steps has been revealed using isoconversional methods. Dehydration comprises the loss of ten water molecules in a relatively narrow temperature interval, resulting in a very complicated reaction mechanism. In addition, density functional theory calculations have been applied for better understanding of dehydration. The second degradation step, related to loss of en, was separated into two single-step processes with Fraser-Suzuki function. The obtained individual steps were described by Johnson-Mehl-Avrami A2 model and estak-Berggren model, respectively. Validation of the proposed kinetic triplets for individual steps was performed using master plot and P,rez-Maqueda criteria. The third degradation step is related to the fragmentation of pyr ion most likely followed with the release of a number of gaseous products.

The main objective of this study is to investigate the potential utilization of some organic additives in clay bricks. It is examined the effects of adding soy crust, wood cutting and coal dust on both durability and mechanical properties of the bricks. In the first set the additives were added and the second set was used for comparing. The main conclusion is that these materials can be used in the above mentioned process.

Uzorci zemljišta iz povšinskog sloja dubine 0 - 10 cm prikupljeni su sa 121 lokacije na gradskom području Novog Sada. Ispitivano područje obuhvatilo je površinu (4 x 5)km2, koja je podeljena na mrežna polja veličine (400 x 400) m2 i u svakom polju uzet je po jedan uzorak. Za 121 uzorak gradskog zemljišta Novog Sada ispitana su fizičko-hemijska svojstva zemljišta, ukupni i pristupačni sadržaj metala (As, Co, Cr, Cu, Mn, Ni, Pb, Zn) i njihova prostorna raspodela. Konturne mape prostorne raspodele metala u zemljištu dobijene su korišćenjem interpolacijske metode običnog kriginga. Za pojedine uzorke izvršeno je razdvajanje čestica po veličinama frakcionisanjem u vodi pomoću sita različitih veličina i identifikovani su minerali prisutni u frakciji prah + glina. Aktivnosti radionuklida „unsupported” 210Pb i 137Cs određene su za jedan deo uzoraka zemljišta u Novom Sadu i za uzorke zemljišta pored fabrike akumulatora u Somboru. Ispitana je i vertikalna distribucija stabilnog i radioaktivnog Pb u zemljištu. Na 14 lokacija u Novom Sadu prikupljeno je 35 uzoraka snega direktno sa asfaltnih puteva i sa zemljanih površina u okolini puteva i na pešačkim ostrvima. Raspodela čestica po veličinama i ukupne koncentracije metala (Al, Ca, Cu, Fe, K, Na, Mn, Ni, Pb, Zn) određene su analizom filtriranih uzoraka, a za 4 uzorka ispitana je morfologija čestica i urađena semikvantitativna analiza čestica u suvoj materiji. Prilikom obrade rezultata merenja primenjene su metode deskriptivne statistike i multivarijacione statističke analize u cilju identifikacije izvora zagađenja i određivanja povezanosti između samih metala i drugih parametara., A total of 121 surface soil samples were collected across the central part of Novi Sad covering a surface area (4 km x 5 km). The physicochemical properties, pseudo total and available metal concentrations (As, Co, Cr, Cu, Mn, Ni, Pb, and Zn) were determined. Contour maps of spatial distribution of the investigated metals were obtained using ordinary kriging interpolation method. Separation of different particle size fractions by wet sieving and identification of minerals in the clay and silt fraction for some soil samples were performed. Specific activities of radionuclides “unsupported” 210Pb and 137Cs were measured in forty soil samples collected in urban area of Novi Sad and industrial area of Sombor (near a battery manufacturer). Vertical distribution of stable and radioactive Pb for two samples from the industrial soil was examined. Thirty five snow samples were collected at fourteen locations near crossroads in Novi Sad. The samples were taken directly from the road surface and from the ground surface in the vicinity of roads and on pedestrian islands. Particle size distribution and total concentration of the metals (Al, Ca, Cu, Fe, K, Na, Mn, Ni, Pb, Zn) were determined for filtered samples. Semi-quantitative analysis of the particles was conducted and morphology of the particles was examined for dry matter of four snow samples. Methods of descriptive and multivariate statistics and geostatistics were carried out for the analysis and interpretation of the data.

A series of nanostructured fluorite-type Ce1-xYxO2-delta(0 LT = x LT = 0.35) solid solutions, prepared via high-energy milling of the CeO2/Y2O3 mixtures, are investigated by XRD, HR-TEM, EDS and Raman spectroscopy. For the first time, complementary information on both the long-range and short-range structural features of mechanosynthesized Ce1-xYxO2-delta, obtained by Rietveld analysis of XRD data and Raman spectroscopy, is provided. The lattice parameters of the as-prepared solid solutions decrease with increasing yttrium content. Rietveld refinements of the XRD data reveal increase in microstrains in the host ceria lattice as a consequence of yttrium incorporation. Raman spectra are directly affected by the presence of oxygen vacancies; their existence is evidenced by the presence of vibration modes at similar to 560 and similar to 600 cm(-1). The detailed spectroscopic investigations enable us to separate extrinsic and intrinsic origin of oxygen vacancies. It is demonstrated that mechanosynthesis can be successfully employed in the one-step preparation of nanocrystalline Ce1-xYxO2-delta solid solutions. (C) 2015 Elsevier Inc. All rights reserved.

Metal concentrations in urban soils of Novi Sad, Serbia were measured and the pollution sources were identified using multivariate statistical methods. During July and August 2010, a total of 121 surface soil samples were collected across the central part of the city covering a surface area of 20 km(2) (4 km x 5 km). Concentrations of As, Co, Cr, Cu, Mn, Ni, Pb, and Zn were determined using the ICP-OES device. Pb concentration varied from 8.9 mg kg(-1) to 999,1 mg kg(-1) at the examined locations. A hierarchical cluster analysis was performed on the available data sets in order to identify associations among metals. GIS mapping technique was applied to produce geochemical maps showing the hot-spots of metal contamination. The elemental relationship in correlation matrix and the results of multivariate statistics supported a natural origin of As, Co, Cr, Mn, and Ni, while Cu, Pb, and Zn originated from anthropogenic inputs. Distribution patterns obtained using GIS mapping technique implied that traffic was the most important source of pollution.

Influence of thermal-annealing-controlled crystallite size on the magnetic/electric properties of Yb substituted Zn-ferrite nanoparticles (ZnFe1.95Yb0.05O4) is studied, and results of the analysis are presented here. Room temperature Mossbauer spectrum of as-prepared sample shows coexistence of the sextet/doublet structure due to the particle size distribution. The central doublet originating from superparamagnetic relaxations of smaller particles is found to constitute the major fraction of the Fe-57 signal in samples obtained by thermal annealing of as-prepared sample at various temperatures in 300 degrees C-800 degrees C range. The determined quadrupole splitting (QS) parameters are significantly higher compared to corresponding bulk counterpart value and display decreasing trend with the crystallite size increase. The similar to 29 nm-sample, obtained by annealing at 800 degrees C, shows bulk-like properties, both in terms of the observed QS value and observed distribution of iron ions within the spinel lattice. Electric resistivity has non-monotonic dependence on crystallite-size, which could be attributed to enhanced disorder in as-prepared material. Partial substitution of iron by ytterbium in Zn-ferrite is found to increase the dielectric constant.

Homogeneous and crack-free TiO2 films with templated mesoporosity were prepared by the dip coating technique using an evaporation-induced, self-assembly method. The synthesized mesoporous TiO2 films were characterized using SEM/TEM, BET and XRD techniques. Degradation reactions of methylene blue and crystal violet dyes were used to test the photocatalytic capability of mesoporous TiO2 films. The degradation kinetics of methylene blue and crystal violet were investigated over a broad range of initial concentrations of the organic dyes. The kinetic data were correlated with the specific surface area and thickness of mesoporous TiO2 films, as well as number of reaction cycles. (C) 2014 Elsevier Ltd. All rights reserved.

Airborne Pb-210, daughter of Rn-222, is frequently used as a tracer in different studies concerning atmospheric transport, sedimentation, soil erosion, dating, etc. Concentration of Pb-210 was measured in 40 soil samples collected in urban and industrial areas in order to get evidence of possible influence of some factors on accumulation of airborne Pb-210 in soil. Different soil properties such as the content of organic matter, free CaCO3, and available phosphorus (P2O5) were measured to explore their possible correlation with the amount of Pb-210 Special attention was given to the correlation between 210Pb and stable lead accumulated in the soil. Several samples were taken near a battery manufacturer to check if extremely high concentrations of lead can affect the uptake of the airborne Pb-210 in soil. Soil samples were also taken at different depths to investigate the penetration of lead through the soil.

During December 2009, snow was collected at twenty two locations across the urban area of Novi Sad, directly from roads and from traffic islands near crossroads. The total metal concentration was determined for each of ten metals (Al, Ca, Cu, Fe, K, Mn, Na, Ni, Pb and Zn) using the ICP-OES analytical technique. Ni was found to have the lowest concentration (0.0265 mg dm(-3)). Na was the metal with the highest concentration (10786 mg dm(-3)), which was the consequence of sodium chloride being used as a de-icing salt on the roads. The metal with the second highest concentration at all locations was Ca; this was most likely the result of soil dust. The Spearman rank correlation coefficients between analyzed metals were calculated to determine how the concentrations of the metals were related. Cluster analysis was performed on the obtained data sets, using both the hierarchical and partitioning methods in order to identify associations among metals and/or locations. It was shown that traffic density was not the most important factor that caused the differences between the concentrations of the metals in the samples.

Антрополошко проучавање Интернет порнографије може да се односи на културну комуникацију између твораца садржаја и аутора порнографских сајтова, као и између аутора сајтова и корисника, при чему је, у случају овог рада, потоња битнија, пошто подразумева надкултурно деловање на Интернету и обухвата кориснике Интернет порнографије као посебну популацију. Циљ овог истраживања је да се кроз категоризације порнографских исечака на Интернету одреде когнитивне шеме и културни модели који објашњавају принципе таквог класификовања и носе информацију о културној мисли, која стоји иза тумачења Интернет порнографије приликом организовања тог дела виртуелне стварности од стране аутора порографских сајтова и корисника. Као методолошка средства, примењена су етнотаксономска анализа и Дандрадеов фолк модел ума. Категорије на сајтовима нису хијерархијски организоване, тако да су међусобне релације проналажене. Резулатати показују да категорије саме по себи не носе довољно значење, већ помоћу блиских категорија учествују у опису концепата, а сами концепти своје значење често одређују у поређењу са осталим концептима. Корисници, такође, врше поделу овог простора, користећи сличне веће сегменте, док су категорије преференције унутар сегмента коме је тренутно посвећена пажња. Једно од уочених понашања корисника које утиче на њихово одређење према катогрисању је представа о односу реално-спектакуларно. Већину исечака корсисници посматрају као одглумљену фикцију за коју учесници имају интерес да је спроводе, што са једне стране, имплицира већу компетeнцију популације корисника, а са друге је повезано са потребом да се представа о личној сексуалности дефинише, оправда и нађе у друштвено прихватљивим оквирима, уз тврдњу: „ниједна животиња није повређена приликом снимања филма“, што донекле одговара контексту изван порнографије у коме је легитимно било које понашање на Интернету, зато што је све виртуелно, те се као вредносни параметри јављају естетска компонента и физичка неугроженост, а св, Anthropological study of the Internet pornography can refer to the cultural communication between the creators of the contents and authors of pornographic sites, as well as between the authors of sites and users, the latter being more relevant to this work as it assumes supracultural activities on the Internet and comprises the pornography users as a distinct population. The aim of this study is to determine, through the categorization of porn clips in the Internet, cognitive schemes and cultural models which explain the principles of such classification and provide the information on the cultural thought that lies behind the interpretation of the Internet pornography during the organization of that particular part of virtual reality by the pornographic sites’ authors and their users. Following methodological means have been applied: ethno-taxonomic analysis and D’Andrade’s folk model of the mind. Categories which appear on web sites are not organized in hierarchies, which means their interrelations had to be inferred. Results showed that categories do not carry sufficient meaning by themselves. Rather, related categories are used to describe concepts, and those concepts frequently derive their meaning from their relation with other concepts. Users also perform the partition of this space by using similar larger segments, whereas the categories themselves are merely preferences within the segment which is currently in focus. One of the observed user behaviours which affects their approach to categorization is their perception of the realistic-spectacular relationship. The users perceive most clips as a staged fiction whose actors take part in it for reasons of self-interest. On one hand, this implies a higher competence of users population; on the other, this relates to the need to define, justify and place the perception of one’s own sexuality within the framework of what is socially acceptable supporting it with the assertion that “no animal was harmed during the

Zirconia-based catalysts were promoted by acid functions (sulfate and phosphate anions) and tested in order to establish catalyst efficiency in test reaction of n-hexane isomerization. The impact of surface and structural properties on the final catalytic performance is also investigated. It is proven that well-established balance between total catalyst acidity, acidic surface density and crystal phase nano-structure determines the catalytic activity in the reaction towards isomerized products. Type of acidic promoter strongly affects the resulted catalytic act. This stands for pyrosylfate groups in sulfated zirconia catalysts and orthophosphate groups in phosphated zirconia catalysts both essential in the favorable reaction run.

Herein a comparative study of five nanocrystalline cerium oxides (CeO2-delta) synthesised by different methods and calcined at 500 degrees C is reported. XRPD analysis showed that stoichiometry parameter delta, crystallite size/strain and lattice constant were only slightly affected by the method utilized. All ceria nanoparticles are nearly spherical in shape with faceted morphology, free of defects and with a relatively uniform size distribution. The average microstrain was found to be approximately 10 times higher than that of bulk counterpart. The absorption edge of nanocrystalline materials was shifted towards a higher wavelengths (red shift) in comparison with bulk counterpart, and band gap values were in the range 2.7-3.24 eV (3.33 eV for bulk counterpart).

Evolution of the structural and magnetic properties of ZnFe1.95Yb0.05O4 nanoparticles, prepared via a high-energy ball milling route and exposed to further thermal annealing/heating, was assessed in detail and correlation of these properties explored. inversion, heating of the sample to similar to 500 degrees C is found to rapidly alter the cation distribution from mixed to normal, in agreement with the known cation preferences. Under the same conditions the crystallite size only slowly grows. By further thermal treatment appreciably. An interrelationship among the lattice parameter, octahedral site occupancy, and crystallite size has been established. The observations are (a) both the site occupancy of Fe3+ at octahedral 16d spinel sites (N-16d(Fe3+)) and the cubic lattice parameter rapidly increase with an initial increase of the crystallite size, (b) the lattice parameter increases with increasing occupancy, N-16d(Fe3+), and (c) there appears to be a critical nanoparticle diameter (approximately 15 nm) above which both the site occupancy and lattice parameter values are saturated. The magnetic behavior of the annealed samples appears to be correlated to the evolution of both the cation distribution and crystallite size, as follows. As-prepared samples and those annealed at lower temperatures show superparamagnetic behavior at room temperature, presumably as a consequence of the Fe3+ distribution and strong Fe3+(8a)-O-Fe3+(16d) superexchange interactions. Samples with a nanopartide diameter greater than 12 nm and with almost normal distributions exhibit the paramagnetic state. The coercive field is found to decrease with an increase of the crystallite size. Partial Yb3+/Fe3+ substitution is found to increase the inversion parameter and saturation magnetization. Detailed knowledge of the thermal evolution of structural/microstructural parameters allows control over the cation distribution and crystallite size and hence the magnetic properties of nanoferrites.

Transition-metal-oxide/transition-metal nanocomposites, such as NiO/Ni, FeO/Fe, and CoO/Co, have been the subject of much recent investigation (i) because of their potential applications and (ii) because they are good model systems for studies of some effects on the nanoscale. They are used, for example, as catalysts, fuel-cell electrodes, magnetic memories, etc. When a nanocomposite is composed of both ferromagnetic (FM) and antiferromagnetic (AFM) nanoparticles, interesting physical properties can occur, such as the phenomenon of exchange bias (EB). A Ni/NiO nanocomposite obtained by the thermal decomposition of nickel(II) acetate tetrahydrate, Ni(CH3COO)(2)center dot 4H(2)O, at 300 degrees C, is composed of NiO (62%) and Ni (38%) with crystallite sizes of 11 and 278 nm, respectively. We observed an increase in the crystallite size for NiO and decrease of crystallite size for Ni, a decrease in the microstrain for both and an increase in the NiO phase content with thermal annealing in air, while high-energy ball milling leads to a decrease of the crystallite size, an increase in the size of the agglomerates, and microstrain as well as reduction, NiO - gt Ni. The lattice parameters of the nanosized NiO and Ni show a deviation from the value for the bulk counterparts as a consequence of crystallite size reduction and the grain-surface relaxation effect. The exchange bias found in a milled sample with particles of 10 nm (NiO) and 11 nm (Ni) disappears for larger particles as a consequence of a coupling-area decrease between the antiferromagnetic and ferromagnetic particles. Due to reduction/oxidation (NiO lt - gt Ni) and size as well as surface-relaxation effects the saturation magnetization value increases/decreases with milling/annealing, respectively. Having in mind the effect of size on the exchange bias, coercivity, and magnetization values, it is possible, by annealing/milling, to tailor the composition and particle size and then control the exchange bias and im

Transition-metal-oxide/transition-metal nanocomposites, such as NiO/Ni, FeO/Fe, and CoO/Co, have been the subject of much recent investigation (i) because of their potential applications and (ii) because they are good model systems for studies of some effects on the nanoscale. They are used, for example, as catalysts, fuel-cell electrodes, magnetic memories, etc. When a nanocomposite is composed of both ferromagnetic (FM) and antiferromagnetic (AFM) nanoparticles, interesting physical properties can occur, such as the phenomenon of exchange bias (EB). A Ni/NiO nanocomposite obtained by the thermal decomposition of nickel(II) acetate tetrahydrate, Ni(CH3COO)(2)center dot 4H(2)O, at 300 degrees C, is composed of NiO (62%) and Ni (38%) with crystallite sizes of 11 and 278 nm, respectively. We observed an increase in the crystallite size for NiO and decrease of crystallite size for Ni, a decrease in the microstrain for both and an increase in the NiO phase content with thermal annealing in air, while high-energy ball milling leads to a decrease of the crystallite size, an increase in the size of the agglomerates, and microstrain as well as reduction, NiO - GT Ni. The lattice parameters of the nanosized NiO and Ni show a deviation from the value for the bulk counterparts as a consequence of crystallite size reduction and the grain-surface relaxation effect. The exchange bias found in a milled sample with particles of 10 nm (NiO) and 11 nm (Ni) disappears for larger particles as a consequence of a coupling-area decrease between the antiferromagnetic and ferromagnetic particles. Due to reduction/oxidation (NiO LT - GT Ni) and size as well as surface-relaxation effects the saturation magnetization value increases/decreases with milling/annealing, respectively. Having in mind the effect of size on the exchange bias, coercivity, and magnetization values, it is possible, by annealing/milling, to tailor the composition and particle size and then control the exchange bias and im

Spherical shaped nanoparticles of series Y2-xEuxO3 (x = 0.06, 0.10, 0.20, and 2) and Gd2-xEuxO3 (x = 0.06, 0.10) were prepared by thermolysis of 2,4-pentanedione complexes of Y, Gd, and Eu. The bixbyite phase of Gd2-xEuxO3 samples was formed at 500 degrees C, whereas the thermal decomposition of Y and Eu complexes' mixtures occurred at higher temperatures. Linearity in the concentration dependence on lattice parameter confirmed the formation of solid solutions. The distribution of Eu3+ in Gd2-xEuxO3 was changed with thermal annealing: in the as-prepared sample (x = 0.10) the distribution was preferential at C-3i sites while in the annealed samples, Eu3+ were distributed at both C-2 and C-3i sites. Rietveld refinement of site occupancies as well as emission spectra showed a random distribution of cations in Y2-xEuxO3. The photoluminescence (PL) measurements of the sample showed red emission with the main peak at 614 nm (D-5(0)-F-7(2)). The PL intensity increased with increasing concentration of Eu3+ in both series. Infrared excitation was required to obtain good Raman spectra. The linear dependence of the main Raman peak wavenumber offers a non-destructive method for monitoring the substitution level and its homogeneity at the micron scale.

The crystal structure and microstructure of as-prepared and annealed Ni0.9Zn0.1O were refined at room temperature in both the Fm (3) over barm and R (3) over barm space groups. It is shown that below the Neel point (458 K), where magnetic ordering triggers the presence of a trigonal strain, the common usage of a higher-symmetry non-admissible space group for crystal structure and microstructure analysis via the Rietveld method may result in both an incorrect structure description and incorrect microstructure parameters (size and strain). More realistic microstructure data can be obtained by whole powder pattern modelling of the powder diffraction data. Increasing the annealing temperature causes a reduction of the trigonal distortion as well as an increase in domain size. Simultaneously, the Raman spectra become less resolved, a clear indication of domain growth and structural evolution of the structure towards cubic symmetry (R (3) over barm - GT Fm (3) over barm).

After controlled thermal degradation of acetylacetonato (AA) complexes, mixtures of monodisperse similar to 5 nm large isometric particles of Y2-xYbxO3 (x = 0.06, 0.10, 0.20, 0.40) were synthesized. Detailed information on nanoparticles microstructure and core crystal structure is reported. The Yb3+ ions occupy preferently C-3i sites for low Yb3+ concentrations, while for 20 at.% Yb3+, a random distribution was found. It was shown that the particle/crystallite size and strain as well as Raman modes positions and widths are influenced by Yb3+ concentration. Crystallographic and Raman spectroscopy results indicate that the particles are core/shell structured with cubic crystalline core and monoclinic-like disordered shell. Most probable particles shell/core volume ratio decreased with annealing at 500 degrees C and the shell disappeared when annealed at 1000 degrees C. (C) 2010 Elsevier B.V. All rights reserved.

In this paper we report results of structural, spectroscopic, and magnetic investigations of MgFe2O4 nanoparticles prepared by soft mechanochemical synthesis. MgFe2O4 nanoparticles crystallize in Fd3m space group with mixed cation distribution and reduced percentage of Fe3+ at tetrahedral (8a) sites. Discrepancy in the cation distribution compared to that in the bulk Mg-ferrite is one of the highest known. X-ray line broadening analysis reveals crystallite size and strain anisotropy. The saturation magnetization, M-sat=62 emu/g measured at 5 K is twice higher than that found in the bulk counterparts. Such high value of M-sat is attributed to the low value of cation inversion parameter (delta=0.69), to the core/shell structure of the nanoparticles and to the surface/volume ratio. Moumlssbauer spectrum collected at room temperature reveals ferrimagnetic ordering between Fe3+ ions in 8a and 16d sites, while zero-field-cooled (ZFC) and field-cooled (FC) M(T) measurements were shown superparamagnetic state above 350 K.

Nanocrystalline LiZn0.5Ti1.5O4 disordered spinel (S.G. Fd (3) over barm) was synthesized by high energy ball milling (HEBM). TEM analysis of the sample has shown that the particle size distribution is broad ranging from 10 to 60 nm. By X-ray line broadening analysis, the average apparent size of the crystallites is found to be 19(1) nm, while the average apparent strain is 26(4) x 10(-4). The cation distribution was found to be metastable, with Zn in octahedral 16d and Ti in tetrahedral 8a position, against their known site preference. After annealing the sample at 650 degrees C for 3 h and slow cooling down to room temperature, superstructure reflections (110), (210), (211) have been observed, indicating a cation ordering in the octahedral sublattice and a combined symmetry reduction (S.G. P4(3)32). The reverse symmetry change P4(3)32 - GT Fd (3) over barm caused by increasing the temperature was studied by in situ XRPD, DSC/DTA, Landaus theory of phase transitions and Raman spectroscopy. An analysis of the topology of the order parameter vector space indicates a biquadratic or linear-quadratic coupling between the order parameters Q(1) and Q(2). In LiZn0.5Ti1.5O4 dilatation expansion of crystal lattice as well as spontaneous strain values are rather small (order of 10(-4)), comparing to e.g. Li1.33xCo2-2xTi1+0.67xO4. (C) 2009 Elsevier B.V. All rights reserved.

Applying a new synthesis route based on the thermal decomposition of a mixture acetylacetonato complexes, Li(AA), La(AA)(3) and Fe(AA)(3), Li, La ferrite (Li0.5La0.08Fe2.42O4) was formed. The element analysis performed by ICP technique and the Rietveld refinement data indicate that the sample is composed of three phases: Li0.5La0.008Fe2.42O4 (69%, SG P4(3)32, a = 8.3445(3) angstrom), La0.14Fe3O4 (16%, SG Fd (3) over barm, a = 8.403(1) angstrom) and LiFeO2 (15%, SG Fm (3) over barm, a = 4.2291(8) angstrom). A partial substitution Fe3+ - GT La3+ in Li ferrite and La insertion at 16c site in Fe3O4 occur at low concentrations. A partial cation ordering at 4b and 12d octahedral sites in Li0.5La0.08Fe2.42O4 was noticed. TEM micrograph shows that the nanoparticles are spherically shaped and that the particle distribution is in the range between 7 and 33 nm. The sample exhibits superparamagnetic behavior, thus the composite has potential industrial applications. (c) 2006 Elsevier B.V. All rights reserved.