以水熱合成法製備二氧化釩粉末之熱致變性質研究

Synthesis of Vanadium Dioxide Powder with Thermochromic Property by Hydrothermal Treatment

何義麟(I-Lin Ho)

指導教授 ： 楊重光

國立臺北科技大學/工程學院/化學工程研究所/碩士(2008年)

摘要

近來由於環保意識的興盛，節能成為一個重要議題。開發出可重覆使用的節能材料是不可抑制之趨勢。具熱致變性質之二氧化釩物質在室溫時以半導體性質存在，而隨著溫度提升，材料性質則由半導體態轉為金屬態，因此在夏天溫度較高時可大幅減少紅外線穿透度使室內溫度降低，冬天時則不影響紅外光穿透，進而達到節能的效果。本實驗利用水熱法成功製備二氧化釩粉末；將五氧化二釩及無水酒精充份攪拌均勻後，再加入適量之去離子水，以超音波震盪將顆粒大小均勻化，並趕去水中溶氧，接者放入450毫升之不鏽鋼高溫高壓釜中進行水熱反應，沉澱樣品待清洗及過濾收集，在80℃下乾燥3小時後，藉高溫且惰性環境下鍛燒，由二氧化釩單斜晶結構轉為可逆之相轉變金紅石結構。本樣品經電子顯微鏡觀察其微觀結構、X-ray繞射儀判斷其結晶性、傅立葉轉換紅外線光譜儀分析其光學性質變化、示差掃描熱差儀探討其熱致變溫度。由SEM結果得知二氧化釩粉末約為200奈米；在低溫(<220℃)水熱法中有助於二氧化釩(B)型態之生成；隨著水熱法溫度增加，二氧化釩會由棒狀錯綜複雜型貌轉為球狀顆粒分佈；在過高的鍛燒處理中會生成部份的十三氧化六釩與二氧化釩(M)結構之混相結構；熱致變之相轉變溫介於68~74℃；二氧化釩粉末經升溫後能有效的降低紅外光穿透率再次證明其熱致變性質。

關鍵字

二氧化釩 ； 水熱法 ； 熱致變材料 ； 節能

並列摘要

Nowadays, energy-saving concept has been an important issue due to the blooming of environmental consciousness. Thermochromic property of vanadium dioxide (VO2) exists semiconductor phase in room temperature and transfer to metal phase when temperature increased to 68℃. Therefore, the IR transmission decreased in summer, which prevented the room temperature increased. In contrast, the IR transmission increased in winter, which created energy-saving effect. In this study, hydrothermal method was employed to prepare vanadium dioxide powder. Vanadium pentoxide powder and ethanol were well mixed with appropriate of amount distilled water. The well mixed powder solution was within ultrasound both, then transferred into a 450 ml stainless steel autoclave to carry out a hydrothermal reaction. The resulting precipitate was collected by filtering, washing, and drying at 80℃ for 3 hours. Vanadium dioxide monoclinic structure was converted to rutile structure through calcining with high temperature at inert atmosphere. SEM, XRD, FTIR and DSC were utilized to acquire the information of morphology, crystallinity, optical properties and thermochromism temperature, respectively.
As estimated from SEM result, the vanadium dioxide powder size is about 200nm. Hydrothermal treatment in low temperature helped to form the vanadium dioxide (B). However, structural morphology was changed from belt shape to round gradually when hydrothermal treatment temperature increased. Crystal of vanadium dioxide (M), (B) type or V6O13 phase were coexisted when calcined in low or high temperature. Thermochromism of phase transfer temperature is between 68℃-74℃, which proved thermochromism property of vanadium dioxide.

並列關鍵字

VO2 ； hydrothermal method ； thermochromism material ； energy saving

參考文獻

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