Characteristic features of the structural properties, phase transitions, and ferroelastic properties in LiK1−xRbxSO4 (x=0, 0.2, and 1) crystals

We report a systematic nuclear magnetic resonance (NMR) study of alkaline ions in LiK1−x RbxSO4 (x=0, 0.2, and 1) crystals, which was performed to investigate the effects of the random distribution of the Rb substitutional cation on the sequence of phase transitions. When a fraction of potassium ions in the pure LiKSO4 crystal is partially replaced by rubidium ions, we compare the structural properties of LiKSO4, LiK0.8Rb0.2SO4, and LiRbSO4 single crystals. The presence of the Rb ions stabilizes the trigonal structure and prevents the breaking of trigonal symmetry at low temperature. The partial substitution of Rb for K changes the transition temperature, and the ferroelastic property of pure LiKSO4 at low temperatures does not appear in the LiK0.8Rb0.2SO4 crystal down to 100 K.