Studies on Aging of Precipitates and Coprecipitation XXXIX. Low Temperature Conductivity of Silver Bromide

Abstract

The following expression is proposed for the electrical conductivity of silver bromide χ=(Ae−W/2kT+KS)e−U/kT,in which S is the magnitude of the active surface. When Ae−W/2kT≫KS the high temperature kind of conductivity predominates. In the opposite case the low temperature kind of conductance predominates. Conductivity-temperature curves of fresh (large S) and well-aged (small s) silver bromide have been determined. In agreement with theoretical expectations it is found that χ=3.0×105e−18,000/RT+Aie−8300/RTin which Ai varies in proportion to the active surface of the product. A pellet prepared from freshly precipitated silver bromide was found to have about 500 times as large a conductance as a pellet prepared from the fused product. At a given temperature the following relation exists between χ and the pressure p applied to the pellet: dlnχ/dp=−k. The value of k increases with decreasing active surface and with increasing temperature. The temperature effect is accounted for by the contribution of the active surface.