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    題名: 共沉澱法製備LaAlO3粉體與粉體性質分析
    其他題名: Preparation and characterization of laalo3 powder by co-precipitation technique
    作者: 程冠博;Cheng, Kuan-po
    貢獻者: 淡江大學化學工程與材料工程學系碩士班
    余宣賦;Yu, Hsuan-fu
    關鍵詞: 鋁酸鑭;共沉澱法;熱分析;LaAlO3;co-precipitation;TG-DTA
    日期: 2008
    上傳時間: 2010-01-11 05:40:17 (UTC+8)
    摘要: 本研究是以共沉澱法,利用氨水共沉澱硝酸鋁和硝酸鑭溶液來製備鋁酸鑭。我們改變氨水的添加量,其添加量為硝酸根莫耳數的0.5、1、1.5和5倍,來觀察對合成粉體的影響。同時以化學沉澱法進行單成分元素的沉澱、分析,然後以物理混合之方式混合鑭與鋁之沉澱物再來與共沉澱做比較。
    我們發現先用沉澱再物理混合的系統是分別形成氫氧化鋁與氫氧化鑭,而共沉澱則是形成鑭鋁氫氧錯合物。兩者在高溫處理後都會形成結晶之鋁酸鑭,但是利用共沉澱的方式其相態較單一,非結晶的雜質也較少,並且可以在較低的溫度下得到結晶之鋁酸鑭粉體。共沉過程中的氨水添加量會對乾燥粉體的組成造成改變,連帶的影響粉體整體的熱行為表現以及熱重損失。氨水對於這些變化的關係並不是線性,而是會隨著添加到達一最大值後產生相反的影響效能。氨水含量為硝酸根莫耳數1和1.5倍的條件下共沉澱鋁酸鑭前趨物粉體,經過700℃3小時的煆燒後即可得到結晶之鋁酸鑭粉體。
    In the present study, crystalline LaAlO3 nanoparticles were synthesized at temperatures as low as 700 oC using a reverse precipitation technique. The aqueous solution, containing the stoichiometric ratios of lanthanum nitrate and aluminum nitrate to form LaAlO3, was dropped in an aqueous solution of NH4OH to form the insoluble metallic salts. The amount of NH4OH used were varied according to [NH4+ from NH4OH]/[NO3ˉ from total metallic nitrates] = 0.5, 1, 1.5, and 5.0, respectively. After centrifugation and drying, the solid precursors were calcined at different temperatures and the resultant particles were characterized using x-ray diffractometry, thermogrametric analysis, differential thermal analysis, infrared spectroscopy, and transmission electron microscopy. The results indicated that the solid precursors obtained by co-precipitating La3+ and Al3+ from the solution can transform to crystalline LaAlO3 at temperature much lower than those obtained by mixing the La3+-contained precipitates and Al3+-contained precipitates. The amount of NH4OH used slightly affected the formation of LaALO3. When [NH4+ from NH4OH]/[NO3ˉ from total metallic nitrates] was controlled at 1.5, the obtained solid precursor can decompose to form crystalline LaALO3 at 700 oC.
    顯示於類別:[化學工程與材料工程學系暨研究所] 學位論文

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