Effects of sintering conditions on microstructures and microwave dielectric properties of Ba6−3x(Sm1−yNdy)8+2xTi18O54 ceramics (x=2/3)

Effects of composition and sintering conditions upon the microstructures and the microwave dielectric characteristics of Ba6−3x(Sm1−btlyNdy)8+2xTi18O54 solid solution (x=2/3) were investigated. The dielectric constant increased and the temperature coefficient of resonant frequency τf could be adjusted from negative to positive with increasing Nd content in the solid solution, while the high Qf factor (>9000 GHz) was obtained. It should be emphasized that the temperature coefficient of resonant frequency was significantly affected by sintering time and the zero-temperature coefficient composition shifted to Nd-rich side with increasing sintering time. The excellent microwave dielectric properties were achieved in the ceramics with y=0.8 sintered at 1340 °C for 12 h: ε=85, Qf=9,460 GHz, and calculated τf=+0.8 ppm/°C.