Computer simulation of Nb-doping PBWO4 crystal

The existing forms of the impurity Nb5+ ions in the Nb:PWO crystals are simulated by the computer simulation technology. The various kinds of defects and substitution reactions in the Nb:PWO crystals are also simulated. By analyzing the calculated results of defect formation energies and solution energies, the optimal positions of the Nb5+ ions and the charge compensating mechanism [NbO3+VO]+–[NbO4]− in the Nb:PWO crystals are obtained; this charge compensating mechanism change the compensating form of oxygen vacancies which relates to 350 nm absorption band, then the 350 nm absorption band is depressed.