Pressure-Induced Phase Transitions in the Spin-Peierls Compound CuGeO_3
Abstract
We have carried out extensive high pressure studies on CuGeO3 using Raman spectroscopy and optical microscopy up to 30 GPa. The pressure-induced transitions in CuGeO3 are sensitively dependent up on the nature of the stress near 7 GPa. When the pressure is strictly hydrostatic, as with methanol/ethanol mixture or helium, Phase I goes to Phase II near 7 GPa and then amorphizes near 18 GPa. With quasihydrostatic media like argon Phase I transforms to a blue-phase (Phase III) near 7 GPa and then to a green colored phase (Phase IV) near 8 GPa. The latter phase is stable up to 20 GPa and transforms to another phase at higher pressures. On pressure release, Phase IV reverses to Phase III, near 5 GPa, which can be quenched and retained, whereas Phase II reverts to Phase I. All the phases have distinct and different Raman spectral features. This complex behavior will be presented and discussed in terms of possible structural changes.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1997
- Bibcode:
- 1997APS..MAR.A2304J