X-RAY-ABSORPTION FINE-STRUCTURE STUDY OF THE B1-TO-B2 PHASE-TRANSITION IN RBCL

Pressure-induced changes in the local structure about Rb atoms in RbCl are investigated by means of x-ray-absorption fine-structure spectros copy. Rb K-edge data were taken in fine steps across the pressure indu ced NaCl-structure (B1)-to-CsCl-structure (B2) transition at 0.55 GPa. Previous diffraction studies of this phase transition indicate severa l martensiticlike properties, including the coexistence of both phases at 0.49 GPa. Our results are consistent with this coexistence of phas es at the transition. In addition, we find no evidence for an intermed iate phase.