Microstructures and microwave dielectric properties of (Ba1−x Sr x )4(Sm0.4Nd0.6)28/3Ti18O54 solid solutions

Abstract (Ba1−x Sr x )4(Sm0.4Nd0.6)28/3Ti18O54 (x = 0.02, 0.04, 0.06, 0.08, 0.1) solid solutions were prepared by the conventional solid-state reaction process. It was found that (Ba1−x Sr x )4(Sm0.4Nd0.6)28/3Ti18O54 ceramics are fully composed of BaSm2Ti4O12 and BaNd2Ti5O14 phases for all the compositions. The increasing x value (0.02 ≤ x ≤ 0.1) in ((Ba1−x Sr x )4(Sm0.4Nd0.6)28/3Ti18O54 ceramics can not only obtain high Q × f value but also effectively enhance the permittivity (ε r). The (Ba1−x Sr x )4(Sm0.4Nd0.6)28/3Ti18O54 ceramic with x = 0.08, sintered at 1440 °C for 4 h, shows excellent microwave dielectric properties of permittivity (ε r) ≈ 93.19, quality factor (Q × f) ≈ 9770.14 GHz (at 3.415 GHz), and almost near-zero temperature coefficient of resonant frequency (τ f ) ≈ +4.56 ppm/°C