A new, layered monoclinic phase of Co3O4 at high pressure
Abstract
We present the crystal structures and electronic properties of a Co3O4 spinel under high pressure. Co3O4 undergoes a first-order transition from a cubic (CB) Fdm to a lower-symmetry monoclinic (MC) P21/c phase at 35 GPa, occurring after the local high-spin to low-spin phase transition. The high-pressure phase exhibits the octahedral coordination of Co(II) and Co(III), whereas the CB phase contains the fourfold coordination of Co(II) and the sixfold coordination of Co(III). The CB-to-MC transition is attributed to the charge-transfer between the di- and trivalent cations via the enhanced 3d–3d interactions.