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Příprava Fe-Ti kompozitů mletím v kulovém mlýnku
Roupcová, Pavla ; Schneeweiss, Oldřich
The materials were prepared by mechanical alloying in the ball mill. The first type of sample consists of pure commercial precursors (TiH2 and ferrihydride). The slightly changes of phase composition of the powder were under the detection limit of X-ray powder diffraction. The MS determined the changes from the first step of milling. The second type of sample was prepared from turnings. The reduction of the splinters volume and the mechanical alloying was running simultaneously. The huge crystalline size differences decreased the credibility of computation of phase composition by XRD. MS was able determined phase composition more exactly and in additional to differentiate crystalline and amorphous FeTi phase.
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X-ray diffraction studies of crystals
Hybler, Jiří
The study brings short review of methods of X-ray diffraction, namely rotation, Weissenberg, precession, Laue, and single crystal diffractometry. Methods of X-ray topography (Schulz, Berg-Barrett and Lang) are briefly mentioned. The lecture and paper are intended to inform researchers non-familiar with methods about their current developments.
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Strmé InAs/GaAs heteropřechody a velmi tenké kvantové jámy vypěstované pomocí MOVPE
Hulicius, Eduard ; Pacherová, Oliva ; Oswald, Jiří ; Hospodková, Alice ; Pangrác, Jiří ; Šimeček, Tomislav ; Melichar, Karel ; Petříček, Otto ; Chráska, T. ; Holý, V. ; Vávra, I. ; Ouattara, L.
We have found that the abruptness and symmetry on monoatomic scale is achievable with MOVPE technique as well. We are able to find only the periodicity in these structures while atomic resolution pictures give reliable thickness values.
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Charge densities and topological analysis
Šlouf, Miroslav
Lecture compares conventional X-ray diffraction analysis on single crystals with more precise techniques based on kappa-refinement and multipole refinement. The results that can be obtained from precise charge denstity studies and topological analysis are listed. Examples taken from practice show how to calculate atomic charges, double-bond characters etc. from both experimental X-ray data and theoretical quantum chemistry calculations.
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