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The structural phase transitions in LiK0.50Rb0.50SO4 mixed crystal

, , , , and . JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 67 (12): 4285-4290 (1998)
DOI: 10.1143/JPSJ.67.4285

Abstract

The structural phase transitions of the LiK0.50Rb0.50SO4 mixed crystal were investigated by Raman spectroscopy and neutron powder diffraction up to 800 K. The results show two first order structural transitions, quite analogous to the transitions in LiKSO4. Raman spectra and diffraction profiles were compatible with average symmetries C-3v(4), C-6(6) and D-2h(16) for the three observed phases, with increasing temperature. The transitions, both reconstructive, are smeared over large temperature intervals, leading to the coexistence of Raman bands and neutron peaks of the different phases and to an anomalous behavior of the lattice parameters into these intervals. In the hexagonal phase, the cell Volume presents a hysteretic behavior depending on the sample thermal history. Raman spectra of the orthorhombic phase shows the high rotational disorder of the SO4 ions, associated with the high Li positional disorder in this high conducting phase.

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