Non-isothermal stationary states, thermoelectric powers and transport processes in α-Ag2Se in a temperature gradient

Abstract

Investigations on non-isothermal steady states, thermoelectric powers and transport processes in the mixed conductor α-Ag2Se have been carried out using the following solid state thermogalvanic cell: ▪ Measurements of the emf E21 between the Pt-leads Pt2 and Pt1 and of E34 between Pt3 and Pt4 yield quantitative informations about the silver activities at the cold and hot end of the α-Ag2Se sample and thus about the Soret-effect, i.e. about the stationary gradient of the silver activity or of the stoichiometry respectively along the sample corresponding to the imposed temperature gradient. From these values the sum of the partial molar entropy of mixing and of the entropy of transport of silver in α-Ag2Se can be calculatedMeasurements of the different thermo-emf's E14 and E23 under the above conditions give values for the corresponding thermopowers in α-Ag2Se. From these thermopowers the Soret-effect can be evaluated, which is in good agreement with the results of the activity measurements.The rate of transport of silver through the sample being subjected to a temperature gradient has been measured for constant silver activities in α-Ag2Se. The silver flux can also be calculated using the results of the Soret-effect. Preliminary measurements show, that experimental findings and calculated values are in agreement within the experimental uncertainties.