Inorganic photochromic and cathodochromic recording materials.

Photochromic materials have the property of changing color under light illumination. Inorganic photochromic materials are frequently cathodochromic as well, that is, they can be colored by electron beam irradiation. This paper describes recent studies at RCA Laboratories of three classes of inorganic photochromic materials: (1) rare-earth-doped CaF(2); (2) transition-metal-doped SrTiO(3) and CaTiO(3); and (3) iron- or sulfurdoped sodalite. Photochromic properties of these materials in both single crystal and powder form, and cathodochromic properties of powders, are discussed.