Effect of LiTaO3 grain sizes on microstructure and properties of Al2O3

Abstract

To investigate the relationship in LiTaO₃ between the non-180° domains and the grain size, nano LiTaO₃ powders were synthesized by sol–gel methods and added into Al₂O₃ to prepare LiTaO₃–Al₂O₃ ceramic composites by hot pressing. The effect of LiTaO₃ grain size on microstructure and properties of Al₂O₃ was investigated. The addition of nano LiTaO₃ powders contributed to the sintering of Al₂O₃ and the relative density of the LiTaO₃–Al₂O₃ ceramic composites was more than 96%. Non-180° domains also formed in the composite and were nearly independent on the grain sizes of LiTaO₃. The bending strength and fracture toughness of Al₂O₃ were improved by adding nano LiTaO₃. A typical “second-phase grain size threshold effect” at around 310 nm grain size of LiTaO₃ additions appeared for the mechanical properties of LiTaO₃–Al₂O₃ ceramic composites.