Calorimetric and optical studies of orthorhombic and cubic CsLiCrO4 crystals

Careful calorimetric and polarization optical studies of a metastable cubic modification of a CsLiCrO₄ crystal (space group ( $F\overline 4 3m$ )) are performed. Anomalies of the heat capacity indicative of structural distortions at 92.4 and 69.1 K were revealed, and the values of the thermodynamic parameters of the phase transitions were determined. The crystal twinning in the intermediate phase was studied. A comparative analysis of the phase transitions occurring in a series of ALiMO₄ crystals (A = NH₄, Cs; M = S, Cr, Mo, W) was performed. First studies of the monotropic structural transformation $F\overline 4 3m$ → Pmcn and the enantiotropic phase transition Pmcn ? P112₁/n were carried out using scanning calorimetry, and the thermodynamic parameters of these transitions were determined.