Effects of Sm substitution on microwave dielectric properties of Ba4La9.33(Ti0.95Zr0.05)18O54 ceramics

Sm substitution for La was investigated for the modification of Ba4La9.33(Ti0.95Zr0.05)18O54 ceramics. A single-phase solid solution with tungstenbronze-like structure formed in the whole range of y values in Ba4(La1−ySmy)9.33(Ti0.95Zr0.05)18O54 ceramics. As Sm content increased, there was a constriction of the b-axis and c-axis, and decrease in the cell volume. The Qf value did not obey the mixing rules and it varied nonlinearly with composition y. Small levels of Sm substitution improved the Qf value with a decrease of dielectric constant. The temperature coefficient of resonant frequency varied from positive to negative and decreased continuously with the increase of Sm content. A near zero τf value (−2.38 × 10−6/°C) was obtained at the composition of y = 0.7.