Optical and photorefractive properties of strongly reduced BaTiO3

Strong reduction of BaTiO3 induced the appearance of an absorption peak around 600-610 nm and a high dark conductivity, both of which increase with increasing reduction level. The carriers change from holes to electrons after reduction. Because of the influence of the high dark conductivity, beam coupling gain becomes highly dependent on incident light intensity, and response time changes little with intensity. For the sample reduced at 10(-15) atm oxygen partial pressure and a temperature of 900 degrees C, the dark conductivity is estimated to be 1.6 x 10(-10) (Ohm.cm)(-1), which increases by about four orders of magnitude after reduction.