Microwave dielectric characteristics of (Bi1−xSmx)NbO4 ceramics

Abstract The effect of sintering temperature on the microwave characteristics of (Bi 1− x Sm x )NbO 4 ceramics was investigated. As the sintering temperature increased from 940 to 1060 °C, the amount of the α-form of (Bi 1− x Sm x )NbO 4 first increased, reached a saturation value, and then decreased. The high temperature form of the (Bi 1− x Sm x )NbO 4 (β-form, triclinic) started to appear at 960 °C for x =0.1, and then its amount increased with the increase of the sintering temperature. The dielectric constant ( e r ) did not apparently change with the increase of Sm content and saturated at 41.5–42.5. The quality factor ( Q × f ) reached a maximum value in samples sintered at 1000–1020 °C and then rapidly decreased with the increase of the sintering temperature for x ⩾0.1. In samples sintered at >1000 °C, the negative temperature coefficient of the resonant frequency ( τ f ) critically increased with the increase of sintering temperature for all compositions. (Bi 1− x Sm x )NbO 4 ceramics sintered at 960 °C and x =0.1 had a minimum τ f value of 1.5 ppm/ °C.