Charge transfer in mixed-valence solids. Part III. Spectra and semiconductivity of chlorocuprates(I,II)

Abstract

Visible and ultraviolet spectra of hexamminecobalt(III) chlorocuprates(I,II) containing copper(I) and copper(II) in all proportions have been measured by diffuse reflectance. The intensities of the intramolecular transitions (ligand field and charge transfer) vary monotonically with the mole fraction of copper(I), but a new absorption band, assigned to intermolecular charge transfer, has the greatest intensity when copper(I) and copper(II) are present in equal proportions. The electrical conductivity of the compounds, both as crystals and compressed powders, is reported. All the mixed-valence compounds behave as ohmic semiconductors, the specific conductivity being greatest for the 50% copper(I) compound, though the activation energy does not vary with composition.