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.
Users
Please
log in to take part in the discussion (add own reviews or comments).