We have studied the pressure-induced phase transformation in a large single crystal of ReO3 at 300 K and (06)-kbar hydrostatic pressure. Inelastic measurements at 1 bar show a pronounced minimum in the T1 mode near the Brillouin-zone boundary (M point). Above Pc=5.2 kbar superlattice reflections with intensities consistent with M3-like rotations of ReO6 octahedra appear. The transformation seems to be continuous (second order), but an anomaly in the superlattice intensity at P=5.4 kbar suggests a further transformation. The M3 phonon softens dramatically as PPc from below, but no substantial changes occur in the long-wavelength acoustic velocities between 0 and 6 kbar.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics