顯微形貌和相變的影響
( 1. 華中科技大學(xué)模具技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，
武漢 430074；
2. 福州大學(xué) 材料研究所，福州 350002)
摘 要: 用Sol-gel方法制備了納米級TiO2， 用XRD分析了粉末的相結(jié)構(gòu)和尺寸， 并用原位TEM和SED技術(shù)詳細(xì)分析了電子束對不同結(jié)構(gòu)TiO2的影響。 XRD結(jié)果表明： 250℃以下干燥的樣品為無定形TiO2， 360℃和600℃熱處理的樣品由銳鈦礦相組成， 750℃熱處理的樣品由銳鈦礦（體積分?jǐn)?shù)30%）和金紅石（體積分?jǐn)?shù)70%）兩相組成， 當(dāng)溫度為950℃時，全部轉(zhuǎn)變?yōu)榻鸺t石。 在電子束照射下， 除了110℃干燥的團(tuán)聚體在短時間內(nèi)未觀察到銳鈦礦和金紅石相外，在250℃和360℃加熱的樣品中均觀察到了金紅石相，甚至全部為金紅石相。 顆粒尺寸增大， 電子束對相變的影響減弱， 600℃保溫1h的樣品在電子束照射下短時間內(nèi)未出現(xiàn)金紅石相；然而當(dāng)樣品處于銳鈦礦和金紅石雙相時， 電子束又促進(jìn)了金紅石相的形成， 這與氧缺陷的增加有關(guān)。 此外， 在電子束的照射下， 無定形的TiO2樣品中還出現(xiàn)了TiC相。
關(guān)鍵字: 電子束； Sol-gel法； TiO↓2； 相變； 顯微形貌
transformation of TiO2 prepared by Sol-gel technique
XIONG Wei-hao1, ZHANG Teng2
（ 1. State Key Laboratory of Die & Mould Technology，Huazhong University of Science and Technology， Wuhan 430074, China;
2. Institute for Materials Research，
Fuzhou University， Fuzhou 350002, China）
Abstract: Nano-sized TiO2 was prepared by Sol-gel technique. The phase and size of the as-derived powders were analyzed by XRD. The effect of electron beam on the microstructures and phase transformation of TiO2 heat treated at various temperatures for different times was studied by in-situ TEM and SED. It is shown that below 250℃ amorphous phase TiO2 is presented. Upon heating the amorphous phase can be transformed to anatase and rutile and 70%(volume fraction) rutile can be detected after being calcined at 750℃ for 1h. The rest was anatase. Given the electron beam, anatase and rutile can be obtained from powders processed at 250℃ and 360℃. With increasing sizes, the effect of electron beam on the process of phase transformation is delayed. Rutile phase can not be observed by beam heating for short time in the sample heat treated at 600℃ for 1h. However, if the two phases of anatase and rutile coexist, the electron beam can facilitate the transformation to the final stable rutile. These changes may be due to the reactive vacuum atmosphere. In addition, a new phase is identified as TiC after beam heating for some seconds in the sample with amorphous phase.
Key words: electron beam; Sol-gel technique; TiO2; phase transformation; microstructure
