Electrochemical Properties of Silver Halides and their Relation to Photography

A survey is given on the properties of AgCl, AgBr, and Ag! as ionic conductors, as electronic conductors and as mixed conductors. The equilibria of disorder are discussed and the relaxation time of point imperfections is estimated. The electrochemical mechanism of dissolution and etching is outlined. The electronic equilibria and their dependence on the surroundings are described by the dependence between the Fermi energy and the halogen pressure or the silver activity. The mobilities of electrons and holes are discussed, especially the drift mobilities and the different kinds of traps ·in light of the formation kinetics of the latent image. Some reasons for the high sensitivity of silver halides are given. Photographic development i:s a surface reaction catalyzed by a low overpotential at the latent image speck, not a redox process at a semiconductor electrode. Bleaching and latensification of inner latent images, however, can be explained by injection processes. The origin and sign of space charges in the surface region of the compounds, their experimental evidence and their influence on the electrochemical and photographic behaviour is considered. Some measurements of instationary polarization at silver halide-metal or -carbon contacts are described