Phase Transition and Crystal Structure of CsHSeO4 and CsDSeO4 Crystals

Takanori Fukami, Shuta Tahara, Keiko Nakasone, Mitsuhiro Seino


DSC, TG-DTA and X-ray diffraction measurements have been performed on cesium hydrogen selenate CsHSeO4 and deuterated CsDSeO4 crystals. The superionic phase transitions for the proton and deuterated compounds were found to occur at 402.6 and 398.1 K, respectively. The thermal decomposition accompanied by hydrolysis in both compounds started at around the transition temperature, and the maximum rate of weight loss from the reaction was observed at around 490 K. The space group symmetry (monoclinic P21/c) and structural parameters were determined at 298 and 355 K. The expansion of the O-H-O hydrogen bond at room temperature by the substitution of deuterium for hydrogen was observed to be 0.015(7) Å. The geometric isotope effect on the hydrogen bond structure by deuteration was realized in the CsHSeO4 crystal. The experimental results denied the existence of a phase transition from phase II to III in the proton and deuterated compounds.

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International Journal of Chemistry   ISSN 1916-9698 (Print)   ISSN 1916-9701 (Online)

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