80.
We report the results of an X-ray diffraction study of CdAl
2Se
4 and of Raman studies of HgAl
2Se
4 and ZnAl
2Se
4 at room temperature, and of CdAl
2S
4 and CdAl
2Se
4 at 80 K at high pressure. The ambient pressure phase of CdAl
2Se
4 is stable up to a pressure of 9.1 GPa above which a phase transition to a disordered rock salt phase is observed. A fit of the volume pressure data to a Birch-Murnaghan type equation of state yields a bulk modulus of 52.1 GPa. The relative volume change at the phase transition at ∼9 GPa is about 10%. The analysis of the Raman data of HgAl
2Se
4 and ZnAl
2Se
4 reveals a general trend observed for different defect chalcopyrite materials. The line widths of the Raman peaks change at intermediate pressures between 4 and 6 GPa as an indication of the pressure induced two stage order-disorder transition observed in these materials. In addition, we include results of a low temperature Raman study of CdAl
2S
4 and CdAl
2Se
4, which shows a very weak temperature dependence of the Raman-active phonon modes.
相似文献