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Study of Alit structure and stability
Pernicová, Kateřina ; Všianský,, Dalibor (referee) ; Dvořák, Karel (advisor)
The diploma thesis deals with the laboratory preparation of the main clinker mineral alite. The theoretical part summarizes the main findings of recent research. The practical part is devoted to the preparation and optimization of the methodology for the preparation of alite polymorph. The main goal was to prepare monoclinic phases of M1 and M3 alites and analyze their properties by available analytical methods.
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Crystal and molecular structure study of garnets from selected localities of the České středohoří Mts.
Píšová, Barbora ; Skála, Roman (advisor) ; Laufek, František (referee)
Major and minor element contents of garnets from mantle peridotites and eclogites brought to the surface by volcanic rocks of the České středohoří Mts. were determined by an electron probe microanalyzer. Garnets are homogenous and their chemical composition corresponds to solid solution containing 65-71 % pyrope, other end members significantly present are almandine, uvarovite and grosulare. This method also help to discover polyphase inclusions chemically corresponding to amphiboles (pargasite, cummingtonite, magnesio-hornblende and katophorite). Next to amphiboles following minerals were found in inclusions: omphacite, carbonates, phlogopite, clinochlore, olivine, apatite, spinel group minerals, and sulfidic phases potentially close to pentlandite. Samples were also analyzed by powder X-ray diffraction. Qualitative phase analysis confirmed pyrope homogeneity. The refinement of crystal structure parameters was performed by the Rietveld method. Raman microspectroscopy showed shifts of individual bands in the Raman spectra compared to those of pure pyrope. Position of bands in spectra differs due to the substitution of Ca for Mg at the dodecahedral sites of the structure. Mutual positive correlations among elements Cr, Ca, Mg, Al, Si, Mn, Ti and Na were observed. Correlations were found also between...
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Crystal and molecular structure study of garnets from selected localities of the České středohoří Mts.
Píšová, Barbora ; Skála, Roman (advisor) ; Laufek, František (referee)
Major and minor element contents of garnets from mantle peridotites and eclogites brought to the surface by volcanic rocks of the České středohoří Mts. were determined by an electron probe microanalyzer. Garnets are homogenous and their chemical composition corresponds to solid solution containing 65-71 % pyrope, other end members significantly present are almandine, uvarovite and grosulare. This method also help to discover polyphase inclusions chemically corresponding to amphiboles (pargasite, cummingtonite, magnesio-hornblende and katophorite). Next to amphiboles following minerals were found in inclusions: omphacite, carbonates, phlogopite, clinochlore, olivine, apatite, spinel group minerals, and sulfidic phases potentially close to pentlandite. Samples were also analyzed by powder X-ray diffraction. Qualitative phase analysis confirmed pyrope homogeneity. The refinement of crystal structure parameters was performed by the Rietveld method. Raman microspectroscopy showed shifts of individual bands in the Raman spectra compared to those of pure pyrope. Position of bands in spectra differs due to the substitution of Ca for Mg at the dodecahedral sites of the structure. Mutual positive correlations among elements Cr, Ca, Mg, Al, Si, Mn, Ti and Na were observed. Correlations were found also between...
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Accuracy of internal and external standard method in quantitative analysis by X-ray powder diffraction
Pérez-Estébanez, Marta ; Viani, Alberto
The X-ray powder diffraction method is known to convey information on the phase composition of samples. Obtaining an accurate quantification of these phases has been long precluded. With the advent of the Rietveld method [1] this became possible. Hedemonstrated the possibility to extract accurate structural information from neutron powder diffraction data. Later, his approach has been extended to x-ray powder diffraction data with successful results. The basics of the Rietveld method lays on the complete exploitation of the whole powder profile without extracting the integrated intensities. The structural information are obtained by fitting the entire profile of the measured diffraction pattern to a calculated diffraction profile. The refinement procedure implements the least square regression and it requires a reasonable scheme of starting values that approximate the real datum.
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