Structure of Cu6PbO8

ABSTRACT

First-principles quantum mechanical calculations based on density functional theory were performed for Cu6PbO8, hexacopper lead octaoxide, murdochite. The computed lattice parameter, density and bond lengths at ambient pressure are in good agreement with experimental data for murdochite. At about 18 GPa a phase transition is predicted, when a polymorph with a Suzuki-type structure, i.e. a close-packed structure with ordered vacancies, is proposed to become stable. The pressure dependence of the structural parameters has been calculated for the two polymorphs and their bulk moduli have been predicted. It is argued that the incorporation of halogen atoms is not a precondition for the stability of murdochite.