Effects of Nd/Sm ratio and glass addition on the microwave dielectric properties of Ba4.5(Sm(0.8−x)NdxBi0.2)9Ti18O54 ceramics

Abstract

Abstract In this study, Ba 4.5 (Sm (0.8− x ) Nd x Bi 0.2 ) 9 Ti 18 O 54 ceramics with various amounts of glass were prepared. The effects of Nd/Sm ratio and glass content on the microstructure evolution and microwave dielectric properties were evaluated. SEM micrographs revealed that the microstructures of Ba 4.5 (Sm (0.8− x ) Nd x Bi 0.2 ) 9 Ti 18 O 54 ceramics with 4 wt.% glass sintered at 1150 °C are uniform and their grain sizes range from 1 to 3 μm. The dielectric constant of Ba 4.5 (Sm (0.8− x ) Nd x Bi 0.2 ) 9 Ti 18 O 54 ceramics increased with increasing sintering temperature or the Nd content, and the τ f value also increases with increasing Nd content. With 6–10 wt.% glass added, Ba 4.5 (Sm 0.24 Nd 0.56 Bi 0.2 ) 9 Ti 18 O 54 ceramics obtain maximum densities at 1100 °C. No second phase was detected in the XRD patterns. Grains are columnar-like and grain size increases significantly with increasing glass content and sintering temperature. The results showed that Ba 4.5 (Sm 0.24 Nd 0.56 Bi 0.2 ) 9 Ti 18 O 54 ceramics with 2 wt.% glass sintered at 1150 °C had a sintering density of 5.6 g/cm 3 , dielectric constant of 87.9, Q · f of 2523 GHz, and τ f of 22.8 ppm/°C.