Study on Free-Pyro Black LiNbO_3 and LiTaO_3 Crystals

Free-pyro black LiNbO_3 and LiTaO_3 wafers were prepared successfully by chemical reduction at (700 °C) and 450 °C respectively under a mixed atmosphere of CO_2 and H_2. Bulk conductivity and optical transmittance of the wafers were measured. The results showed that the pyroelectric effect for the reduced wafers was almost eliminated and the transmittance decreased considerably. The reduction process did not change Curie temperatures of LN and LT wafers