Sinterability and Dielectric Properties of LiTaO₃-Based Ceramics with Addition of CoO

Lithium tantalite (LiTaO₃) is a common piezoelectric and ferroelectric crystal, but the LiTaO₃ polycrystalline ceramics have rarely been reported, and their refractory character presents difficulties in their fabrication. In this study, LiTaO₃-based ceramics with different amounts of CoO were prepared by pressureless sintering at 1250 °C, and the effects of the amount of sintering aid on the sinterability, microstructure, and dielectric properties of the ceramics were investigated. The relative densities of the LiTaO₃-based ceramics were significantly improved by the addition of CoO powder. The LiTaO₃-based ceramics achieved the highest relative density (89.4%) and obtained a well-grained microstructure when the added amount of CoO was 5 wt.%. Only the LiTaO₃ phase in the ceramics was observed, indicating that the ions Co diffused into the LiTaO₃ lattices and mainly existed in two forms: Co²⁺ and Co³⁺. The effects of the added amount of CoO on the dielectric properties of the LiTaO₃-based ceramics were studied thoroughly. Consequently, the dielectric constant was enhanced, and the dielectric loss decreased in the LiTaO₃-based ceramics with the addition of CoO. The optimal value was obtained at 5 wt.% of CoO-added LiTaO₃-based ceramics.