文化大學機構典藏 CCUR:Item 987654321/16502
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    jsp.display-item.identifier=請使用永久網址來引用或連結此文件: https://irlib.pccu.edu.tw/handle/987654321/16502


    题名: 六方晶(Ba,Sr)(Ti,Ga)O3合成與特性研究
    作者: 何志鵬
    贡献者: 材料科學與奈米科技研究所
    关键词: 六方晶鈦酸鋇
    鍶離子摻雜
    拉曼
    微波特性
    日期: 2009
    上传时间: 2010-09-07 15:39:25 (UTC+8)
    摘要: 在本研究中，我們使用固態法成功合成Ba1-ySryTixGa1-xO3樣品，我們以BaTixGa1-xO3(x=0.1、0.2與Sr：1~~9%)為母體，對A-site Ba2+進行Sr2+取代，在進行取代後，樣品的結構由六方相 混合相 正方相，這結果是與文獻報導相符合。其中Sr2+大於1%後無六方相純相，混合相則隨Ga的增加而縮小。在Sr2+較高摻雜時，則只有正方相存在。在Sr2+低摻雜時，隨著燒結溫度提高後，六方晶的比例會提高，但Sr2+高摻雜量時，則不論燒結溫度為何，只有正方晶相存在，此結果也與室溫拉曼結果吻合。在光譜的結果上顯示，相同的組成會隨燒結溫度增加，而使六方相特徵模態變強而正方晶特徵模漸消失。
    在摻雜的過程中，因為Sr2+的離子半徑較Ba2+小，所以Ba1-ySryTixGa1-xO3樣品的單位晶胞體積會隨著Sr的摻雜量的增加而減少，然而密度的變化並沒有隨Sr的摻雜量的增加而降低，這是因為六方相本就是熱力學中亞穩相，在溫度下降後有可能因為不穩定而轉為正方相。在微波特性分析上，隨著摻雜量的增加，Qxf值與K值都有大幅下降，明顯因為晶相轉變(六方 正方)，而這意味著只要有正方晶產生，則Qxf值與K值就會有很大的下降值產生，這也說明了六方相(BTO)具有良好的微波特性，有極高的應用價值。
    The (Ba,Sr)(Ti,Ga)O3 samples are synthesized by the solid state method in air and the parent components BaTi1-xGaxO3 (ABO3) are substituted Ba for Sr (x=0.1, 0.2 and Sr: 1%~9%) in this work. The structure of samples are changed from hexagonal to mixed phases then tetragonal through the A-site substituting process, which is consistent with the thermodynamic prediction on literature. The all samples can form the pure hexagonal structure when the Sr-concentration is lower than 2%, and the mixed phase region is decreasing with Sr-doping level increasing. In the higher Sr-doping region, the structures of samples are tetragonal only.
    The hexagonal structure of (Ba,Sr)(Ti,Ga)O3 samples are increasing with the sintering temperature increasing in the lower Sr-doping region, but the tetragonal structure is dominant in the higher Sr-doping region. This is consistent with the result of room temperature Raman spectrum measurements. Because the Raman spectrum is reported that the tetragonal modes of BaTiO3 will go away and the intensity of hexagonal modes of BaTiO3 systems are increasing with sintering temperature increasing.
    During the substituting proceeding, because the ion-radius of Sr2+ is smaller than Ba2+, the volume of unit cell of (Ba,Sr)(Ti,Ga)O3 samples are decreasing with the Sr-concentration increasing. Although the atomic weight of Sr is lighter than Ba, but the density of samples aren’t also decreasing with Sr-doping level increasing, because the hexagonal phase is a metastable structure on thermodynamic, which is due to tetragonal phase replacing hexagonal phase in higher doping region at room temperature.
    The microwave property measurement are showed that because the main phase of samples will change from hexagonal to tetragonal with the Sr-doping level increasing, which is due to the Qxf value and K value of samples are dramatic dropping with Sr-concentration increasing. It means that if the samples are included the tetragonal structure, whose Qxf value and K value are hugely decreasing, so it also proofs that the hexagonal BaTiO3 material has very good microwave property and a large potential for application.
    显示于类别:[化學工程與材料工程學系暨碩士班] 博碩士論文

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