Phototropic effects in oxides. I. Titanium dioxide

Abstract

Abstract The previously known photoropic effect caused by iron impurity in titanium dioxide was studied in some detail. In addition, nickel, chromium, and copper were shown to give rise to marked effects, while slight effects were caused by cobalt, manganese, and certain rare earths. The necessity of water for the promotion of the effect was demonstrated, and evidence was obtained that suggests that the phototropism is a phenomenon taking place at the surfaces or interfaces of the host oxide. A mechanism is discussed.