O⁻⁻-Lücken-Dipole in Rubidiumhalogenidkristallen

Abstract

Dielectric loss measurements are reported for RbCl, RbBr, and RbJ crystals containing O⁻⁻ions. The frequency and temperature dependence can be approximated by a Debye curve. The dipole moment is interpreted as being due to O⁻⁻ ions associated with anion vacancies. Activation energies for reorientation of the dipole are 0.60 eV for RbCl, 0.56 eV for RbBr, and 0.50 eV for RbJ.

The deviations of the experimental dielectric loss curves from a Debye curve are interpreted. The dielectric losses decrease and the center uv absorption changes during annealing due to association of the centers into aggregates. A detailed analysis of the kinetics for RbBr indicates the formation of O⁻⁻-pair centers as the first step. The activation energy for association isE ₂=0.79 eV.