First-principles study of pressure-induced phase transition and electronic property of PbCrO3

Abstract

We have performed a systematic first-principles investigation to calculate the structural, electronic, and magnetic properties of PbCrO3, CrPbO3 as well as their equiproportional combination. The local density approximation (LDA) + U and the generalized gradient approximation + U theoretical formalisms have been used to account for the strong on-site Coulomb repulsion among the localized Cr 3d electrons. By choosing the Hubbard U parameter around 4 eV within LDA + U approach, ferromagnetic, and/or antiferromagnetic ground states can be achieved and our calculated volumes, bulk moduli, and equation of states for PCO-CPO in R3 phase and PCO in Pm3¯m or R3c phases are in good agreement with recent experimental Phase I and Phase II [W. Xiao etal., PNAS 107, 14026 (2010)], respectively. Under pressure, phase transitions of R3 PCO-CPO to Pm3¯m PCO at 1.5 GPa and R3 PCO-CPO to R3c PCO at −6.7 GPa have been predicted. The abnormally large volume and compressibility of Phase I are due to the content of CrPbO3 in the experimental sample and the transition of PbO6/2 octahedron to CrO6/2 upon compression. Our electronic structure study showed that there will occur an insulator-metal transition upon the phase transitions. Clear hybridization of Cr 3d and O 2p orbitals in wide energy range has been observed.