LAUSR

Abstract Crystal structures and microwave dielectric properties of (1-x) LaGaO3-x SrTiO3 (x = 0.4, 0.5, 0.6) and 0.4SrTiO30.6LaGaO3-yCeO2 (y = 0, 0.05, 0.1, 0.2) ceramics were investigated. As the x values increased, the orthorhombic changed to tetragonal perovskite structure at x = 0.6 in LaGaO3-SrTiO3 system ceramics. However, numerous secondary phases were detected in LaGaO3-SrTiO3 system ceramics. Surprisingly, CeO2 additives could effectively suppress formation of secondary phases of 0.4SrTiO3-0.6LaGaO3 ceramics as Ce ions could be incorporated into host crystal lattices, leading to significantly improvement of optimal Q × f values from 35,354 GHz to 62,150 GHz. The Raman spectra exhibited that the modes associated with CeO2 phase became more obvious with increasing CeO2 additives. The 0.4SrTiO30.6LaGaO3-0.05CeO2 ceramics, sintered at 1475 °C/4 h, exhibited superior microwave dielectric properties with er = 32.9, Q × f = 62,150 GHz and τf = − 26.6 ppm/°C.