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標題: | 氣相燃燒合成SiO2及TiO2奈米複合氧化物之研究 The Formation of SiO2 and TiO2 Nano-size Composite Materials in Gas Phase Combustion Synthesis |
作者: | Chia-Cheng Hsu 許嘉政 |
指導教授: | 馬小康 |
關鍵字: | TiO2-SiO2複合氧化物,前置物,TTIP,HMDSO,Rutile, Titania/silica complex oxides,Precursors,TTIP,HMDSO,Rutile, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 本研究係於預混甲烷火焰,加入TTIP和HMDSO前置物以燃燒合成方式形成TiO2-SiO2之複合氧化物。實驗條件包括調整當量值、氧氮比和不同前置物濃度,從火焰觀察、火焰溫度、產物晶相和顆粒大小,探討TiO2-SiO2複合氧化物之形成機制。
在火焰觀察方面,可經由調整兩種前置物(Precursors)之不同比例得知火焰顏色變化,只受TTIP影響,火焰顏色會由藍色轉為紅色,而在燃燒反應中HMDSO並不會使火焰顏色變化。在火焰溫度方面,隨著兩前置物的添加,火焰溫度會比之前未加入前置物之火焰溫度還低,這是由於兩前置物之加入燃燒反應為吸熱反應,其中HMDSO之吸熱反應大於TTIP。 在晶相觀察方面,當固定兩前置物之流量比時,在任何當量值、氧氮比和收集高度時,燃燒合成TiO2-SiO2之複合氧化物在XRD之晶相觀察下可知TiO2-SiO2複合氧化物中之TiO2全為Rutile相,而在當量比、氧氮比和收集高度之提升時,則會造成合成TiO2-SiO2複合氧化物中Rutile的含量的增加。在TEM之觀察下,可知TiO2-SiO2複合氧化物中無定形的SiO2均勻地包覆在TiO2顆粒表面形成核殼結構,加入少許SiO2會有效抑制TiO2晶粒的成長,當量值和氧氮比之提升,而造成火焰溫度的提高,也都會使TiO2晶粒的粒徑變大,而收集高度的提高也會使TiO2晶粒的粒徑變大。 The study focuses on premixed CH4 +O2+N2 flame and adjusted ratio of TTIP/HMDSO for composing Titania/silica complex oxides (TiO2-SiO2). The experimental conditions include the equivalence ratio, the ratio of oxygen/nitrogen, the collecting height and the concentration of different precursors. The composing Titania/silica complex oxides mechanisms are studied by the flame observation, flame temperature, crystalline phase and particle sizes. Flame color is affected by adjusting the ratio between two precursors. The main reason is that the TTIP changes the flame color from blue to red. However, HMDSO does not change the flame color. The higher equivalence ratio and the oxygen/nitrogen ratio cause higher flame temperatures. When two precursors are added, the flame temperature decreases due to both precursors causing endothermic reactions. When the equivalence ratio, the ratio of oxygen/nitrogen and collecting height increase, the composite result of TiO2 phase of titania/silica complex oxides (TiO2-SiO2) is Rutile phase. Also, the amount of Rutile is increasing. In the aspect of particle size analysis, the higher equivalence ratio and the oxygen percentage cause temperature rise and more collision chances that lead to bigger particle size. Heterogeneous nucleation of SiO2 on the surface of TiO2 is the main reason of core-shell nanocmposites formation. In addition, the size of TiO2 nanoparticles of titania/silica complex oxides increases with the collecting height in the flame. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/30514 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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