The effect of LnAlO3 (Ln = Nd, Sm) additives on the densification, phase evolution, microstructure and dielectric properties of BaO-Nd2O3-5TiO2 (BNT5) ceramics was investigated. The LnAlO3 (Ln = Nd, Sm) had greatly influence on the densification behavior of the BNT5 ceramics and the grain sizes of BNT5 ceramics could be effectively refined by LnAlO3 additive. The microstructure of BNT5 ceramics was transformed from quasi-rectangular grain to columnar grain while the content of LnAlO3 was increasing. The dielectric constant (εr) and the temperature coefficient of resonant frequency (τf) were reduced with the increase of LnAlO3 content, whereas the Q×f values showed a non-linear behaviour with LnAlO3 content increasing. The BNT5 ceramics doped with 12.5 wt% SmAlO3, sintered at 1320°C for 4 h, had the excellent dielectric properties of εr = 62.78, Q×f = 11108 GHz and τf = -1.55 ppm/°.
Densification behavior and phase evolution of Mg-doped sialon