Effect of Al₂O₃ content on dielectric properties of Al₂O₃/LiTaO₃ composite ceramics

The effect of Al₂O₃ addition (5vol%, 10vol%, 15vol% and 20 vol%) on the dielectric properties of Al₂O₃/LiTaO₃(ALT) composite ceramics prepared by hot-press sintering were investigated. The results show that the dielectric constant and dielectric loss of ALT composite ceramics decrease with the increasing frequency. Comparing with pure LiTaO₃ ceramics, adding 5vol% Al₂O₃ can increase its dielectric constant and decrease its dielectric loss, while the dielectric constant and dielectric loss of ALT composite ceramics increase consequently with more Al₂O₃ adding. With Al₂O₃ contents increasing, the Curie temperature initiately increases and then decreases, reaching the maximum at 5vol% Al₂O₃. Thus, Al₂O₃/LiTaO₃(ALT) composite ceramics is a good composite system because the addition of the second phase Al₂O₃ promotes sintering of LiTaO₃, and slightly improves its dielectric properties.