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研究生：	林世忠 Lin, Shih-Chung
論文名稱：	陳化處理對化學沈澱法生成之奈米二氧化鈦粉末之晶粒成長及相轉換的影響
指導教授：	向性一 Hsiang, Hsing-I
學位類別：	碩士 Master
系所名稱：	工學院 - 資源工程學系 Department of Resources Engineering
論文出版年：	2004
畢業學年度：	92
語文別：	中文
論文頁數：	66
中文關鍵詞：	相轉換、晶粒成長、陳化、二氧化鈦
外文關鍵詞：	crystallite growth, titanium dioxide, aging, phase transformation
相關次數：	點閱：122 下載：20
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本研究利用沈澱法製得二氧化鈦膠體。部分膠體再利用陳化製程處理獲得未陳化及陳化處理之兩種二氧化鈦。主要工作在觀察不同陳化處理的條件對膠體粉末性質及煆燒過程中銳鈦礦晶粒成長及銳鈦礦到金紅石相轉換的影響。並計算銳鈦礦晶粒成長及銳鈦礦到金紅石相轉換的活化能，進而瞭解並解釋其機構。
未經過陳化處理的沈澱物主要為非結晶質相，且具有較多的氫氧基、結晶水及銨根；經過陳化處理的沈澱物主要為銳鈦礦相，且隨著陳化時間的增加，膠體粉末中含有的氫氧基、結晶水及銨根的含量隨之減少。
未經過陳化處理的膠體粉末在煆燒過程中其銳鈦礦晶粒成長較為快速且造成較為嚴重的凝聚，可能為粉末中含有較多的氫氧基所造成。銳鈦礦相的晶粒成長控制機構為oriented attachment，具有較快的晶粒成長速度及較低的晶粒成長活化能（53 kJ/mol）。銳鈦礦到金紅石相轉換溫度較低，而相轉換機制為介面控制為主。
經過陳化處理的膠體粉末其粉末中的氫氧基隨著陳化時間的增加而減少。在煆燒過程中其銳鈦礦晶粒成長速度較為緩慢。陳化同時可以減輕煆燒後粉末的凝聚現象。銳鈦礦相晶粒成長之速率決定步驟為晶界擴散，其銳鈦礦晶粒成長的活化能（約200～250 kJ/mol）較未陳化之樣品為高。利用較輕微的凝聚現象及較高之晶粒成長活化能，經由陳化處理能有利於生成晶徑較小的純銳鈦礦相粉末。銳鈦礦到金紅石相轉換機制轉為擴散反應控制為主。

This study used precipitation method to synthesize titania gel, and then the gels were aged for various time to get two kinds of titania: unaged and aged gels. Effects of the aging on the properties of gel powders (crystalline phase, thermal behaviors), anatase crystallite growth and anatase to rutile transformation in calcination were investigated in this study. The activation energy of anatase crystallite growth and anatase to rutile transformation were also calculated to know and explain the mechanisms.
The crystalline phases of the gels with and without aging treatment were amorphous and anatase, respectively. Much larger amounts of H2O, OH-, and NH4+ existed in unaged gel than in aged gel. The amounts of H2O, OH-, and NH4+ in gel powders decreased with increasing aging time.
Anatase of unaged gel powder owned faster crystalline growth rate and worse aggregation during calcination than that of aged gel powder due to the existence of much more amounts of OH- in unaged powder. The mechanism of anatase crystalline growth was controlled by oriented attachment. Anatase owned faster crystalline growth rate and lower activation energy of crystallite growth ( 50 kJ/mol ) for unaged gel powder. The temperature of anatase to rutile transformation was lowered and the mechanism of transformation was interface controlled.
Amounts of OH- in gel powder decreased with increasing aging time. Therefore, the crystallite growth rate of anatase during calcination for aged gel powder was slower than unaged gel powder. Aging process decreased the extent of aggregation of powders after calcination. The rate controlled step for anatase crystallite growth was grain boundary diffusion. Activation energy of anatase crystalline growth ( about 200-250 kJ/mol ) for aged gel powder was higher than unaged gel powder. Based on the above results, pure and small crystallite size of anatase powder can be obtained by aging treatment due to the less aggregation and higher activation energy of anatase crystalline growth. The mechanism of anatase to rutile transformation was diffusion controlled.

摘要.................................................................I
ABSTRACT............................................................II
致謝................................................................IV
表目錄............................................................VIII
圖目錄..............................................................IX
第一章 緒論..........................................................1
1 前言.............................................................1
2 研究背景.........................................................1
3 研究目的.........................................................2
第二章 理論基礎與前人研究............................................3
1 二氧化鈦之基本性質...............................................3
2 製備奈米二氧化鈦粒子.............................................5
2.1 化學沈澱法.....................................................5
2.2 溶膠-凝膠法（Sol-gel）.........................................5
2.3 其他...........................................................6
3 沈澱後之陳化處理.................................................7
4 反應動力學.......................................................8
4.1 晶粒成長反應速率式、活化能.....................................9
4.2 晶粒成長活化能................................................10
4.3 相轉換反應速率式..............................................11
4.4 相轉換活化能..................................................12
第三章 研究方法與步驟...............................................18
1 實驗原料........................................................18
2 實驗步驟........................................................18
3 特性分析........................................................21
3.1 粉末結晶相分析................................................21
3.2 熱差分析......................................................21
3.3 粉末鍵結行為分析..............................................21
3.4 粉末晶徑及粒徑分析............................................22
3.5 相轉換量分析..................................................24
3.6 顯微影像及結構分析............................................25
第四章 結果與討論...................................................26
1 陳化處理對膠體粉末性質的影響....................................26
1.1 陳化處理對膠體粉末結晶性的影響................................26
1.2 陳化處理對膠體粉末熱行為的影響................................33
1.3 陳化處理對膠體粉末鍵結行為的影響..............................33
2 陳化處理對銳鈦礦到金紅石相轉換行為的影響........................34
3 陳化處理對膠體粉末粒徑、凝聚程度的影響..........................34
4 陳化處理對活化能的影響..........................................42
4.1 陳化處理對晶粒成長活化能的影響................................42
4.2 陳化處理對銳鈦礦到金紅石相轉換活化能的影響....................49
第五章 結論.........................................................60
參考文獻............................................................61
APPENDIX Ⅰ.........................................................66
                                    

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校內：2005-02-06公開
校外：2005-02-06公開

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