Effects of A-site La3+ substitution by Nd3+ on microwave dielectric properties and microstructure of CaTiO3-La(Ga0.5Al0.5)O3 ceramics

Microstructure and microwave dielectric properties of (1−x)CaTiO3-x(La1−θNdθ)(Ga0.5Al0.5)O3 were investigated in this work. The crystal structure of 0.64CaTiO3-0.36(La1−θNdθ)(Ga0.5Al0.5)O3 transformed from the orthorhombic crystal system into the tetragonal when θ = 0.4. It was found that the Q × f value has been promoted by the partial La3+ substitution by Nd3+. The excellent microwave dielectric properties with εr = 43.6, Q × f = 49,091 GHz, and τf = −8.68 ppm/°C were obtained at 50 at.% substitution of La3+ by Nd3+ in 0.64CaTiO3-0.36La(Ga0.5Al0.5)O3. Moreover, the results displayed that all the samples of (1−x)CaTiO3-x(La0.5Nd0.5)(Ga0.5Al0.5)O3 (x = 0.33 - 0.37) exhibited Q × f ⩾ 33,449 GHz, 43 ⩽ εr ⩽ 46.1, and −12 ppm/°C ⩽ τf ⩽ −0.73 ppm/°C.