Electrical polarization of lead bromide crystals. II

Abstract

Electrical currents are measured as a function of time after application of a dc voltage on a cell arragement +C/PbBr2/C-. The presence of nonlinear polarization phenomena has been established from a test of Ohm's law, the superposition principle, and from initial and steady-state conductivities calculated from the polarization curves. In addition, nonlinear potential profiles were measured. The polarization effects are attributed to the build-up of space charge regions near the electrodes in view of the fact that the electrode process is slow compared to the velocity of the charge carriers in the bulk of the crystal. The steady-state current is limited by an electrode process with an activation enthalpy of 0.45 ± 0.05 eV. The cathode is more effective in blocking than the anode.