Date of Award

1994

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

This investigation describes a theoretical and experimental examination of the defect properties of rubidium chloride. A theoretical study of the defect properties of RbBr and RbI is also presented.;Defect energy calculations were carried out on RbCl, RbBr and RbI using the HADES code and electron-gas potentials that were fitted to the crystal properties. Damping of the long-range dispersion energy was introduced during fitting of the potential and in the calculation of perfect lattice and defect properties.;In addition, defect energy calculations were done on Rb{dollar}\sb2{dollar}S using potentials developed for the RbCl:S{dollar}\sp{lcub}2-{rcub}{dollar} system. These calculations represent the first theoretical study of the defect energies of Rb{dollar}\sb2{dollar}S.;Ionic conductivity measurements were made on pure, strontium-doped and sulphide-doped rubidium chloride using a new automated system. The data were analysed by means of a nonlinear least squares fitting routine. The analysis of the data suggested that both Schottky and anion Frenkel defects play a role in matter transport in RbCl. Cation interstitials were also found to be present in a small concentration. Vacancy pairs were found to contribute to diffusion, as had been indicated previously in diffusion studies of RbCl{dollar}\sp{lcub}1,2{rcub}{dollar}.;The calculated defect energies and the experimental enthalpies were in good agreement, suggesting the reliability of both the data analysis and the calculation methods used.

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