Pressure- and temperature-dependent Raman spectra of CaFeO oxygen defect perovskite.

The Raman spectra of CaFeO were investigated up to 21.8 GPa at room temperature and up to 1073 K at ambient pressure, respectively. A phase transition begins around 13.6 GPa and it is reversible after decompression. No temperature-induced phase transition was observed due to the quality of Raman spectra at temperatures above 773 K. The effects of pressure and temperature on the Raman vibration were quantitatively analyzed. All the observed Raman active vibrations of CaFeO show positive linear pressure dependences and negative temperature dependences with different slopes. Combined with previous experimental results, the isothermal and isobaric mode Grüneisen parameters of CaFeO were estimated, and the intrinsic anharmonicity was discussed.