Thermoelectric Power of CuCl Containing CdCl₂

The thermoelectric power of CuCl has been measured as a function of temperature between 200° and 400°C, using Cu‐metal electrodes. Measurements were made on pure material, and also on material doped with CdCl₂ in concentrations between 0.01 and 1.0 mole %. The results for pure CuCl are intermediate between previous results for AgBr and AgCl, and the effect of doping is very similar to that in AgBr. Comparison of the CuCl results with those for the silver halides suggests that in CuCl cation Frenkel defects are predominant, with the Cu⁺ interstitial more mobile. Quantitative values for the defect parameters could not be derived, apparently because of the limited solubility of CdCl₂, but they are probably comparable with the silver halides. Additions of CaCl₂, SrCl₂, ZnCl₂, and PbCl₂ gave less informative results; PbCl₂ showed what is believed to be an electronic effect at high temperatures. Conductivity measurements were also made on all specimens. The activation energy for pure CuCl was 1.06 eV.