Search

M20 M21

/ 709 699 43 M20 M21 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).

An order-disorder phase transition of nanosize Li-ferrite (Li0.50Fe2.50O4) was studied by DSC measurements and in situ XRPD technique. The phase transition temperature is found to be 762 °C (DSC) and (745±5) °C (XRPD). Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 2004

Many properties of chalcogenide amorphous semiconductors, such as electric conductivity, optical constants etc. depend on the type of the structural unit in the amorphous structure i.e. distribution of the nearest neighbor atoms. Obviously the identification of the type of the structural units is of great importance. Cu-25 [AsSe1.4I0.2](75) amorphous system and its crystalline phase prepared by slow cooling of the melt were analyzed on automatic X-ray diffractometer equipment. Using X-ray diffraction data we obtained the structure factor (SF). The reduced radial distribution function (RDF) was obtained in two ways: using standard method, Fourier transformation of SF, and maximum-entropy method. RDF analysis results are in agreement with model calculation, which proves the domination of tetrahedral structural units. 7th European Powder Diffraction Conference (EPDIC 7), May 20-23, 2000, Barcelona, Spain

Istraživanje u okviru doktorske disertacije obuhvata uzorkovanja inhalativne frakcije praškastih materija generisane u zubotehničkoj laboratoriji i procesom brušenja čelika EN 90MnCrV8, primenu savremenih metodologija uzorkovanja, analizu uzorka laserskom difrakcijom i analizom slike, zasnovanom na mikrografijama skenirajućeg elektronskog mikroskopa i statističku obradu podataka. Osnovni cilj istraživanja je razvoj funkcionalnog modela za evaluaciju rezultata merenja karakteristika praškastih materija, koji je obuhvatio identifikaciju, procenu i vrednovanje karakteristika prahova, u cilju unapređenja tačnosti rezultata u vezi sa karakterizacijom čestica. Složena geometrija čestica je ispitana analizom 14 parametara, 6 koji definišu veličinu i 8 parametara koji opisuju morfološke karakteristike, upotrebom dva softvera za analizu slike. Dobijeni rezultati obrađeni su primenom metode analize glavnih komponenti i hijerarhijske klaster analize, čime se prevazišao problem subjektivnog prilaza i izvršila redukcija i selekcije reprezantativnih parametara na osnovu kojih se može dovoljno dobro definisati i okarakterisati uzorak. Тhis PhD thesis presented the development of the functional model for evaluation оf measuring results of powder materials’ characteristics, which involved the identification, assessment and evaluation of particles characteristics, in order to improve the accuracy of the results. Sampling of inhalation fraction of the powder materials’ was done in the dental laboratory and grinding process of the EN 90MnCrV8 steel. Particle analysis was performed whit laser diffraction and image analysis based on micrographics from scanning electron microscopy and data were statistically analyzed. The complex particle geometry was examined by analyzing 14 parameters, 6 which define the size and 8 parameters that describe the morphological characteristics, using two image analysis software. To deal with a large number of the numerical parameters used to characterise the particle geometry and the nonlinear relationships among these parameters, principal component analysis (PCA) and hierarchical cluster analysis (CA) algorithm was applied to identify representative numerical descriptors within each group.

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.