Pressure-induced phase transitions in antiferroelectric CsBi(MoO4)2

The high-pressure Raman spectra of antiferroelectric CsBi(MoO4)2 were measured at room temperature. These studies indicated that this crystal exhibits two pressure-induced phase transitions at 0.6 and 1.0 GPa. The stable phase in the 0.6–1.0 GPa range was identified as having the same structure as the ambient-pressure ferroelastic phase observed below 125 K. The transition at 1.0 GPa is connected with significant distortion of the MoO42− tetrahedra and Bi3+ coordination sphere. The results suggest that the phase above 1.0 GPa may have the same structure as the high-pressure phase observed in KDy(MoO4)2, KY(MoO4)2 and KTb(MoO4)2 crystals. Upon releasing pressure, the high-pressure phase transforms directly into the ambient-pressure phase. The origin of the observed suppression of the intermediate phase is discussed. Copyright © 2004 John Wiley & Sons, Ltd.