A structural analysis of lead hydroxyvanadinite

Abstract

Hydroxyvanadinite, Pb₁₀(VO₄)₆(OH)₂, was prepared by the co-precipitation method and analyzed by X-ray absorption spectroscopy (XANES, EXAFS), infrared spectroscopy, Raman scattering and X-ray diffraction (XRD). The results showed that the structure is very similar to that of vanadinite, Pb₁₀(VO₄)₆Cl₂, with space group P6₃/m (176) and cell parameters a = 10.2242(3) Å and c = 7.4537(2) Å. A Rietveld refinement of the structure was performed using vanadinite as the starting model and fixing the geometry of the vanadate ion as a rigid body. First-principles Density Functional embedded cluster models are developed to analyze electronic structures, bonding, and densities of states. Interaction of Pb with the OH channel anion is examined in detail, as an important structural feature. A periodic band structure approach was used to obtain a further estimate of relaxed atomic coordinates.