電漿電弧氣凝合成法製備氧化鎢-氧化鈦奈米微粒之研究

Preparation of Tungsten Oxide - Titanium Oxide Nanoparticles by a Plasma Arc Condensation Technique

劉宜泰(Yi-Tai Liu)

指導教授 ： 蘇程裕

國立臺北科技大學/機電學院/製造科技研究所/碩士(2008年)

摘要

本研究利用電漿電弧作為加熱源，蒸發鎢靶材與二氧化鈦奈米粉末，並藉由一套吹氣裝置，氣凝合成不同相態氧化鎢-氧化鈦奈米材料，分別探討不同電漿氣（氬氣及氬氣+10%氫氣）及不同腔體壓力(200~760Torr)對生成奈米氧化鎢-氧化鈦的相態、結構之變化所產生的影響。研究結果顯示隨著腔體壓力的增加，奈米微粒的尺寸有逐漸增加的趨勢。在電漿氣為氬氣時所製備的氧化鎢-氧化鈦奈米微粒中氧化鎢的相態為W24O68，氧化鈦的相態為Ti2O3；而在電漿氣為氬氣+10%氫氣時所製備的氧化鎢-氧化鈦奈米微粒中氧化鎢的相態為W3O，氧化鈦的相態為TiO2。
電漿氣體為氬氣時所製備的氧化鎢-氧化鈦奈米微粒在大約小於326nm波長時，開始出現光吸收特性，而在電漿氣為氬氣+10%氫氣時則大約在小於367nm波長時，開始出現光吸收特性。在熱性質方面，電漿氣為氬氣+10%氫氣，在腔體壓力200Torr與760Torr下所製備的氧化鎢-氧化鈦奈米微粒，在300℃溫度以下都能夠保持原本的相態，而隨著溫度上升至500℃，氧化鎢的相態將會先開始改變，且伴隨著另一個氧化鎢WO3相態的出現，而當溫度到達600℃時，在腔體壓力200Torr下所製備的奈米微粒中氧化鈦的相態也開始發生改變。
在氣體感測方面，電漿氣體為氬氣或氬氣+10%氫氣，腔體壓力在200Torr下製備的氧化鎢-氧化鈦奈米微粒在工作溫度為150℃時，因能量不足而無法完全將NO2氣體脫附，而當工作溫度上升到200℃時，氧化鎢-氧化鈦奈米微粒即具有足夠的能量可以將吸附的NO2氣體脫附，而能達到氣體感測的應用。此外電漿氣體為氬氣，腔體壓力在200Torr下所製備出的氧化鎢-氧化鈦奈米微粒在200℃溫度下對低濃度(3ppm)的NO2氣體具有感測特性。但當工作溫度升高至250℃時，奈米微粒將會受到NO2氣體的毒化，而使其本身的感測能力下降。

關鍵字

電漿電弧 ； 氣凝合成法 ； 氧化鎢 ； 氧化鈦 ； 奈米微粒

並列摘要

By a modified plasma arc gas condensation technique, in this study we synthesized evaporated the tungsten target and titanium dioxide nanoparticles into tungsten oxide nanostructures and titanium oxide nanostructures with different phases. The influence on preparing tungsten oxide nanostructures with different Plasma gas（argon or argon+10%hydrogen）and chamber pressures(200~760Torr) will also be considered. It can be shown that the size of nanoparticles increases with the increment of chamber pressures. And the corresponding phases of tungsten oxide and titanium oxide are W24O68 and Ti2O3 when argon is used for Plasma gas; when argon+10% hydrogen is used, the phases are W3O and TiO2. Under the first setting, The optical absorption appears as wavelength of tungsten oxide - titanium oxide nanoparticles is approximately less than 326 nm. For the second setting, using argon+10%hydrogen, it will appear as wavelength is less than 367 nm.
Some further consequences are also obtained under the second setting. First, from the aspect of thermal stability, the phase tungsten oxide - titanium oxide nanoparticles won’t be changed as long as the temperature is below 300℃ and chamber pressures is under 200 Torr and 760 Torr. However, when the temperature is up to 600℃, the phase starts changing.
Second, from the aspect of gas sensing, due to energy, nanoparticles is not able to get out of NO2 gas completely when the temperature is around 150℃. Not Until the temperature is increased to 200℃ will nanoparticles accumulate enough energy to get out of NO2 gas. This accomplishes the application of gas sensing.
Via using argon for Plasma gas, tungsten oxide - titanium oxide nanoparticles also has gas sensing for NO2 (3 ppm) when the temperature is below 200℃ and chamber pressures is under 200 Torr. But as the temperature increases up to 250℃, nanoparticles will be poisoned by NO2. Then the ability of gas sensing might be affected.

並列關鍵字

Plasma Arc ； Gas Condensation Technique ； Tungsten Oxide ； Titanium Oxide ； Nanoparticles

參考文獻

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