Study of the high pressure phase evolution of Co3O4

This work presents a detailed study of the crystal structure of Co${}₃$O${}₄$ under pressure. $I\phantom{\rule{0}{0ex}}n\phantom{\rule{0.333em}{0ex}}s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u$ high-resolution x-ray diffraction coupled with Raman spectroscopy at pressure up to 60 GPa reveals the occurrence of three phase transitions. The ambient-pressure cubic Fd-3m structure distorts to an Fddd orthorhombic lattice, followed by the monoclinic C2/m and P2${}₁$/c phases at higher pressure. This systematic experimental approach leads to the determination of so far unreported phase transitions and equations of state as well as to the solution of contradictory results reported in the literature.