Light–induced charge transport processes in photorefractive barium titanate crystals doped with iron

3 ) are annealed in a hydrogen atmosphere at various temperatures. After these reducing treatments, absorption, light–induced absorption changes, two–beam coupling direction, photo electron paramagnetic resonance (photo EPR), dark and photoconductivity as well as bulk photovoltaic current density are investigated. The samples are electron conductive and the charge transport is governed by only one level, which is identified by photo EPR as Fe²⁺/Fe³⁺. The photoconductivity exceeds the dark conductivity for intensities above 1 kWm^-2. A relation between the absorption constant and the Fe²⁺ concentration is derived. From the known charge transport parameters the advantageous photorefractive properties of optimized reduced BaTiO₃:Fe are deduced; possible response times in the millisecond range at an intensity of 10 kWm^-2 are estimated. Received: 22 January 1997/Accepted: 23 January 1997