OPTICAL-MODEL OF POSITRON AND EFFECTIVE CHARGES OF OXYGEN IONS IN METAL-OXIDES

The optical positron model allowing for the positron repulsion by a nu clear Coulomb field in the Landau-Lifshitz approximation is invoked to derive an equation for calculating the effective charges eta(-e) of o xygen ions in metal oxides (a) from measured half-widths Gamma (mrad) of angular distributions of annihilation photons arising in crystals b y two-quantum annihilation of positrons from bound states of positronanion systems and (b) from short lifetimes tau(1) of annihilation time distributions. Effective charges of oxygen ions calculated for a rich variety of metal oxides agree with their literature values gained by non-positron methods to within the scatter in these values. Effective charges calculated by the ''positron'' method vary in the series of ox ides in much the same way as their ''non-positron'' counterparts. The calculated ''positron'' effective charges of oxygen ions in metal oxid es may serve as reference data in solving theoretical and applied prob lems in physics and chemistry of solids and various problems of materi als science.