COMPOSITION DEPENDENT ELECTRONIC CONDUCTIVITIES AND HALL-COEFFICIENTS OF MIXED IONIC-ELECTRONIC CONDUCTORS .4. THE HIGH-TEMPERATURE PHASE OF SILVER TELLURIDE

The electronic conductivity, sigma-e, and the Hall coefficient, R(H), of Ag2 + sigma-Te are experimentally determined at temperatures from 200-degrees-C and at values of the composition parameter, sigma, covering the entire stability range. The composition is varied and monitored by in situ coulometric titration. The evaluation of the experimental data yields a harmonic conduction band, while the anharmonicity of the valence band becomes obvious at higher temperatures. The experimental data are consistent with predominant scattering of electrons and holes at longitudinal acoustic phonons. Accordingly, the electronic relaxation time depends on energy and temperature as tau-approximately-epsilon-1/2 . T-1.