Influence of chemical reduction on optical and electrical properties of LiTaO3 crystal

Reduced lithium tantalate (LiTaO3, LT) wafers were prepared by chemically reducing regular congruent LT wafers in mixed iron and lithium carbonate powders under a flowing nitrogen atmosphere. The electrical conductivity, Curie temperature, infrared spectrum, UV–vis transmittance, piezoelectric constants and dielectric properties of the LT wafers before and after reduction were measured. In comparison with regular LT wafers, it was found that both the electrical conductivity and the optical absorption in the visible region are greatly increased after reduction, which is beneficial for eliminating pyroelectric discharge and for high accuracy device processing. In addition, we also found that the piezoelectric and dielectric properties of the chemically reduced wafers remain almost the same, a prerequisite for fabricating SAW devices. The effects of mechanisms related to chemical reduction on the evolution of the physical properties of LT wafers are also discussed.