| Summary: | 碩士 === 國立臺南大學 === 材料科學系碩士班 === 98 === SrTiO3 is an excellent candidate system in lead-free ceramic materials because of its a wide range of applications in integrated microelectronics. Recently, there has been an increasing interest in strontium titanate materials for microwave tunable applications, such as frequency-tunable resonators and filters operating in the GHz range. In this work, the Sr1-1.5xBixTiO3 and Sr1-xMgxTiO3 ceramics have been prepared by solid-state reaction method. Effect of the bisumth and magnesium content on the crystal structure and dielectric properties of ceramic were studied.
This work is composed of two parts. First, the ceramics of Sr1-1.5xBixTiO3 solid solution were sintered for bismuth concentration range 0≦x≦0.1. could be successful synthesized in this work, and investigated the phase transion and dielectric properties of Bi-doped with different concentraction by using X-ray diffraction, SEM, DSC, dielectric constant and Raman scattering. As a result, the x-ray diffraction and Raman scatting profiles of Sr1-1.5xBixTiO3 are characteristic of the coexistence of cubic and orthorhombic, with increasing bismuth contents at x≧0.05. The formation of solid solution is restricted to x≦0.02；The maximum value of dielectric constant at x=0.05 was 1200. The phase transition point shifts to high temperature as bismuth content increases. Second, the x-ray diffraction and Raman scatting profiles of Sr1-xMgxTiO3 are characteristic of the coexistence of cubic and hexagonal, with increasing magnesium contents at x≧0.1. The formation of solid solution is restricted to x≦0.1. Mg doping itself does not induce ferroelectricity or a relaxor-like behavior in strontium titanate.
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