First-Principles Study on the Electronic Structures for Y3+:PbWO Crystals
First-Principles Study on the Electronic Structures for Y^3＋：PbWO4 Crystals

The possible defect models of Y3+:PbWO crystals are discussed by defect chemistry and the most possible substituting positions of the impurity Y3+ ions are studied by using the general utility lattice program (GULP). The calculated results indicate that in the lightly doped Y3+:PWO crystal, the main compensating mechanism is 2YPb++VPb2-], and in the heavily doped Y3+:PWO crystal, it will bring interstitial oxygen ions to compensate the positive electricity caused by YPb+, forming defect clusters of 2YPb++Oi2-] in the crystal. The electronic structures of Y3+:PWO with different defect models are calculated using the DV-X method. It can be concluded from the electronic structures that, for lightly doped cases, the energy gap of the crystal would be broadened and the 420 nm absorption band will be restricted; for heavily doped cases, because of the existence of interstitial oxygen ions, it can bring a new absorption band and reduce the radiation hardness of the crystal.