The hole trappers related to lead vacancy in PbWO4 crystal

Several lattice structures around a lead vacancy VPb2− in PbWO4 (PWO) are optimized using a plane-wave pseudo-potential formulation within the framework of density function theory, with generalized gradient correction in the form of Perdew–Wang-91. The electronic structures around VPb2− in the PWO crystal are studied using the molecular-cluster model within the framework of the fully relativistic self-consistent Dirac-Slater theory by using a numerically discrete variational (DV-Xα) method. By analyzing the lattice relaxation and electronic structures around VPb2− we can reasonably believe that once VPb2− is formed in PWO crystal, O2− turns to be prior to trap holes to compensate the electrical negativity of VPb2− Pb2+ may never be the hole-trap compensating VPb2− and Pb3+ and Pb4+ in PWO crystal may not actually exist. The possible defect micro-model caused by VPb2− in the as-grown PWO crystal is that each VPb2− creates a VK+−VF− aggregate color center.