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Characterization of phase transitions by the analysis of crystal structures
(2009)
- In this thesis results of the investigations of the mechanisms of solid-solid phase transitions are reported on basis of the exemplary characterization of the phase transition of the metalorganic compound Eu(SC36H49)2 and of the inorganic transition-metal compounds TiI3 and CrOCl. The phase transitions were surveyed temperature dependently by the performance of single-crystal X-ray diffraction experiments and measurements of the magnetic susceptibility. The X-ray diffraction experiments were carried out as data collections of integrated intensities of reflections and as measurements of profiles on selected reflections in so-called omega-2theta maps. The data sets of the integrated intensities were used to determine the crystal structures at different temperatures. By the comparison of the high- and the low-temperature crystal structures the mechanisms of the phase transitions of the compounds Eu(SC36H49)2 and TiI3 were determined. Furthermore the transition temperatures of all three compounds were determined by temperature-dependent measurements of intensities of superstructure reflections. From the omega-2theta maps the monoclinic lattice distortion of the low-temperature phase of CrOCl was determined.
