| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 88 === The microwave dielectric properties and the microstructures of Ca1-xNd2x/3TiO3-Li1/2Nd1/2TiO3 and Ca1-xLa2x/3TiO3-Li1/2Nd1/2TiO3 were investigated. Ca1-xNd2x/3TiO3-Li1/2Nd1/2TiO3 and Ca1-xLa2x/3TiO3-Li1/2Nd1/2TiO3 ceramics was prepared by conventional solid-state method. The value x was chosen as 0.39 since Ca1-xNd2x/3TiO3 ceramics exhibited a maximum Q×f value of 8600(GHz) at x=0.39. The dielectric properties were found to strongly depend upon the sintering temperature .The dielectric constant ?捯 and the Q×f value of Ca1-xNd2x/3TiO3-Li1/2Nd1/2TiO3 ceramics increased with increasing sintering temperature. After reaching maximum values at 1400℃,they decreased due to abnormal grain growth .In the (1-y)Ca1-xNd2x/3TiO3-yLi1/2Nd1/2TiO3 and (1-y)Ca1-xLa2x/3TiO3-yLi1/2Nd1/2TiO3 system, the microwave dielectric properties can be effectively controlled by varying the y value. At 1400℃, 0.55Ca1-xNd2x/3TiO3-0.45Li1/2Nd1/2TiO3 ceramics gives a dielectric constant ?捯 of 101, a Q×f value of 5300(GHz) and a ?輎 value of +13(ppm/℃), and 0.5Ca1-xLa2x/3TiO3-0.5Li1/2Nd1/2TiO3 ceramics gives a dielectric constant ?捯 of 105, a Q×f value of 6974(GHz) and a ?輎 value of +4.5(ppm/℃). Results of XRD analysis and scanning electron microscopy are also presented.
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