Effects of annealing atmosphere on photorefractive BaTiO3

Nominally undoped BaTiO3 crystals, processed in atmospheres of various oxygen partial pressure at 900degreesC and 1000degreesC, respectively, were fabricated and systematically investigated. The photorefractive properties are sequentially controlled by the factor from dark decay, deep/shallow trap, deep/shallow trap with hole/electron competition to dark conductivity, as the oxygen partial pressure is reduced. The trend is similar for both of the processing temperature, however, the compensation point is shifted about three of oxygen partial pressure. This can be attributed to a higher oxygen vacancy concentration at higher processing temperature.