Nonisothermal transport properties of alpha-Ag2 + deltaS : Partial thermopowers of electrons and ions, the soret effect and heats of transport

Abstract

The ionic and electronic partial thermopowers and the Soret effect of alpha-Ag2 + deltaS (low temperature phase) have been studied as functions of temperature and deviation from stoichiometry delta by means of a nonisothermal galvanic cell. From a combination of these data with results from additional measurements of the partial entropy of silver metal in alpha-Ag2 + deltaS, the heat of transport of silver metal is determined. The measured transport properties are discussed in respect to the defect structure and isothermal transport properties of alpha-Ag2 + deltaS and information on the individual heats of transport of the mobile point defects is extracted. We observe a strong composition dependence of QAg* which can be explained within our formal analysis. The electronic properties can be interpreted within the model of a non-degenerate electron gas. The scattering factor of electronic defects in the statistical description of thermopower is equivalent to the electronic heat of transport in the phenomenological description.