HIGH-PRESSURE PHASE-TRANSITION AND EQUATION OF STATE OF CSI

Structural properties of CsI at high pressure have been investigated by the use of synchrotron x-ray diffraction techniques with the diamond-anvil cell at 300 K. The results indicate that the material undergoes a continuous distortion from B2 to an hcp-like phase, which is stable to at least 302 GPa. The intermediate orthorhombic phase is geometrically different from previous assignments and 10% denser. With the new structure, the p-V results of static pressure experiments, shock-wave studies, and theoretical calculations are now in good agreement. © 1990 The American Physical Society.