Charge transfer in mixed-valence solids. Part VI. Spectra and semiconductivity of mixed crystals of hexachloroplumbates(II,IV) and hexachloroindates(III)
Abstract
A series of hexachloroplumbate(II,IV) salts, Co(NH3)6PbxIn1–xCl6, has been prepared and characterised by chemical analysis and X-ray powder diffraction. Diffuse reflectance spectra of all the compounds have been measured, and the mixed-valence absorption band identified. Two-probe D.C. conductivity measurements are reported. All the compounds with x > 0·1 are ohmic semiconductors; the specific conductivities at room temperature are proportional to x2, indicating that carrier formation requires pairs of PbCl62– and PbCl64–. The semiconduction activation energy is independent of concentration for x > 0·2 and equal to 0·73 eV. The Seebeck coefficient of Co(NH3)6PbCl6 is + 0·9 mV/°C at room temperature. The optical and conductivity data are discussed in the light of the model put forward previously to explain the comparable properties of hexachloroantimonates(III,V).
 
                



 Please wait while we load your content...
                                            Please wait while we load your content...
                                        