High-pressure Raman spectroscopic study of magnetite Fe₃O₄

Abstract

We report in situ Raman spectroscopic studies of magnetite in a diamond-anvil cell under hydrostatic conditions up to 40 GPa at room temperature. With increasing pressure, the frequencies of the three modes A_1g, F_2g and E_g increase continuously up to about 24 GPa with pressure derivatives of 2.7, 4.5 and 1.4 cm^-1/GPa, respectively. Upon elevation of pressure to nearby 30 GPa, the F_2g mode starts to display a variation in the spectra and its intensity gradually decreases due to the cubic-orthorhombic phase transition. The split mode into B_1g, B_2g, B_3g from F_2g completely disappears at a pressure of 30 GPa.