• Free-standing black LiNbO₃ and LiTaO₃ wafers were fabricated via a chemical reduction method under a mixed atmosphere of CO₂ and H₂.
• The volume conductivity and optical transmittance of the black LiNbO₃ and black LiTaO₃ wafers were measured. The results show that the pyroelectric effect of the wafers was essentially eliminated, and the transmittance decreased significantly.
• The reduction process did not alter the Curie temperature or piezoelectric properties of the LN and LT wafers, enabling charge neutralization even under instantaneous potential generation.
• Black lithium niobate (LiNbO₃) prepared using this reduction technique exhibits a high ability to neutralize charges even when a potential is generated instantaneously.
• The piezoelectric performance of black lithium niobate wafers shows no obvious difference from that of standard wafers. Therefore, black reduced lithium niobate wafers are widely used in the fabrication of high-frequency SAW devices.