| Summary: | 碩士 === 中國文化大學 === 化學工程與材料工程學系奈米材料碩士班 === 104 === In this work, we are synthesized the all Ba1-xSrxTi1-y,FeyO3 (x=0.00, 0.01, 0.03, 0.05, 0.07 and y=0.1, 0.2) ceramics by the mixed oxide method and studied the structure and microwave dielectric properties of samples. The SEM images are observed the BaTiO3 grains have been growth with sintering temperature increasing, when the sintering temperature is higher than 1300oC, the samples are showed the abnormal grain growth (AGG) phenomenon.
The XRD patterns of the Sr-doping samples are showed two structure types of the samples; one is hexagonal Barium titanate (h-BaTiO3) phase with symmetric space group (P63/mmc) and the other is tetragonal Barium titanate (t-BaTiO3) phase with symmetric space group (P4mm). The structures of the samples are transferred from hexagonal phase to mixed phases then tetragonal phase through the Sr-doping process.
The phase-purity and lattice parameters of samples were established by X-ray diffraction results and analyzed by the TOPAS software (Rietveld profile-fitting method). The h-BaTiO3 phase of Strontium doping sample is decreasing with Sr-doping increasing, and the t-BaTiO3 phase of samples is increasing with doping level increasing, the phase transferred rate of samples is decreasing with Fe concentration increasing.
The room temperatures Raman spectrum of samples are observed the h-BaTiO3 and t-BaTiO3 phonon modes. There are also shown the same phase transformation behavior during the Sr-doping process. The Qxf and K-values of samples are both increasing with Sr-concentration increasing, which microwave dielectric property is correlated with its phase transformation.
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