| Ba6-3xLn8+2xTi18O54 (Ln=Sm, Nd, La, etc) solid solutions are the typical high-εmicrowave dielectrics, which have very important applications in microwave communication technology.The trend to miniaturization of microwave telecommunication intensively requires research and development of microwave dielectric systems with high dielectric constant because the size of microwave resonance takes in inverse proportion to the square root of theεr. The aporia of the research is how to keep theτf no more than 1ppm/℃when the material has higherεr. The Q×f should be high as far as possible at the same time to make sure the electronic device is stabe and has low wastage.The influence of composition and technique on the microstructure and properties of Ba6-3xLn8+2xTi18O54 ceramics have been investigated. The Ba6-3xSm8+2xTi18O54 ceramics calcined at 1100℃, mixed with 25 mol% Nd2O3, sintered at 1320℃show good microwave dielectric properties ofε=79.42,τε=-57ppm/℃, Q×f=3240(1GHz).Moreover, the effects of compostion, ionic substitution and process conditions upon the microwave dielectric properties, microstructure and phase constitution of BNT and BST ceramics were investigated in this thesis. The influence of impurity on the BNT ceramics was also discussed, especially for La and Y doped samples. |
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