Phase Transitions in CsH 2 PO 4 Under High Pressure

Abstract

Dielectric constant measurements at low temperature and X-ray diffraction measurements at room temperature were carried out under high pressure up to 1.42 GPa and 10 GPa, respectively, for a hydrogen-bonded crystal CsH 2 PO 4 . By the dielectric measurements, we found a new antiferroelectric phase (AFE II), that is probably the phase predicted theoretically by Schuele and Schmidt. The locations of the two triple points were determined at m 153.4C and 0.59 GPa for PE, FE and AFE I, and at m 168.5C and 1.11 GPa for of PE, AFE I and AFE II. By X-ray diffraction, we confirmed the high-pressure phase V proposed by Rapoport et al. and found a new high-pressure phase VII. Keywords: Csh 2 PO 4FerroelectricsDielectric ConstantX-ray DiffractionHigh-pressure Transition