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

The ionic and electronic partial thermopowers and the Soret effect of α-Ag2 + δS (low temperature phase) have been studied as functions of temperature and deviation from stoichiometry δ 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 α-Ag2 + δS, 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 α-Ag2 + δS 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.