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

Abstract Microstructure and microwave dielectric properties of (1− x )CaTiO 3 – x (La 1 − θ Nd θ )(Ga 0.5 Al 0.5 )O 3 were investigated in this work. The crystal structure of 0.64CaTiO 3 –0.36(La 1 − θ Nd θ )(Ga 0.5 Al 0.5 )O 3 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 La 3+ substitution by Nd 3+ . The excellent microwave dielectric properties with e r = 43.6, Q  ×  f  = 49,091 GHz, and τ f = −8.68 ppm/°C were obtained at 50 at.% substitution of La 3+ by Nd 3+ in 0.64CaTiO 3 –0.36La(Ga 0.5 Al 0.5 )O 3 . Moreover, the results displayed that all the samples of (1− x )CaTiO 3 – x (La 0.5 Nd 0.5 )(Ga 0.5 Al 0.5 )O 3 ( x  = 0.33 – 0.37) exhibited Q  ×  f  ⩾ 33,449 GHz, 43 ⩽  e r ⩽ 46.1, and −12 ppm/°C ⩽  τ f ⩽ −0.73 ppm/°C.