Reaction Sequence and Effects of Calcination and Sintering on Microwave Properties of (Ba,Sr)O-Sm2O3-TiO2 Ceramics

[[abstract]]The reaction sequence of 0.15(Ba0.95Sr0.05)O· 0.15Sm2O3· 0.7TiO2 ceramics during heating as well as the effects of calcination and sintering on microwave properties were investigated. Quantitative microscopic analysis was performed to obtain the volume fraction of the phases. It was found that the amount of second phase, especially TiO2 (rutile), greatly affected the temperature coefficient of resonant frequency of the ceramics. The higher the amount of TiO2 phase, the more positive or the less negative the temperature coefficient of resonant frequency. The temperature coefficient of BaO · Sm2O3· 5TiO2 was calculated using the logarithmic mixing rule to be −30 ppm/°C. The volume fractions of the phases varied with conditions of calcination and sintering. Therefore, by varying calcination and/or sintering temperature, the temperature coefficient of resonant frequency could be adjusted to nearly zero.[[fileno]]2020301010078[[department]]材料