研究A位離子摻雜對六方晶鈦酸鋇性質影響

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Title:	研究A位離子摻雜對六方晶鈦酸鋇性質影響 Study the A-site doping effect of hexagonal Barium Titanate
Authors:	龎亦鴻
Contributors:	化學工程與材料工程學系奈米材料碩士班
Keywords:	六方晶鈦酸鋇鍶摻雜相轉變介電性質 hexagonal BaTiO3 Sr-doping phase transformation dielectric property
Date:	2016-06
Issue Date:	2016-08-02 14:11:53 (UTC+8)
Abstract:	本次實驗中，我們以混合氧化物法合成所有陶瓷樣品Ba1-xSrxTi1-yFeyO3 (x=0.00, 0.01, 0.03, 0.05, 0.07 ; y=0.1, 0.2)，並研究樣品結構以及微波介電性質。於SEM微結構分析圖中能觀察到鈦酸鋇的晶粒會隨著燒結溫度提升而增大，當樣品燒結溫度高於1300℃時，樣品會產生異常晶粒生長現象。鍶摻雜樣品的X光繞射圖則呈現出兩個結晶類型，一種為六方晶相，空間群為P63/mmc，另一種則是四方晶相，空間群為P4mm。樣品的結構透過鍶摻雜的過程，會由六方相變成混合相，再由混合向轉變成四方相的結構。本實驗會以X光繞射數據計算出樣品各相之相對比例及晶格常數，並用TOPAS軟體進行資料擬合法分析。擬合後的數據顯示，隨鍶摻雜量增加六方相鈦酸鋇的相對比例會下降，而四方相鈦酸鋇相對比例會上升，相轉變的情況會隨著鐵摻雜量的增加而減緩。樣品的室溫拉曼光譜觀能察到六方相鈦酸鋇以及四方相鈦酸鋇的振動模式，拉曼光譜結果顯示出鍶摻雜過程中與X光繞射相同的向轉變。結果顯示，樣品的Qxf值與K值都隨著鍶摻雜濃度提升而增加。樣品的微波介電性質是與其相變化密切相關。 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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