A simulation study was made of extrinsic defects in lead tungstate crystal. The results revealed that monovalent ions preferentially entered the Pb sites, whereas pentavalent ions preferentially occupied the W sites, and both of them simultaneously produced O vacancies in order to maintain charge neutrality. The solution energy of trivalent dopants was a strong function of the dopant cation radius. They generally occupied Pb sites, with the excessive charge balanced mainly by Pb vacancies. In some cases, however, an O interstitial ion might also coexist. Binding energy calculations demonstrated a strong tendency towards cluster formation among trivalent dopant ions and Pb vacancies.

Computer Simulation Study of Extrinsic Defects in PbWO4 Crystals. Q.Lin, X.Feng: Journal of Physics - Condensed Matter, 2003, 15[12], 1963-73