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【答案】应助回帖
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对天空说lrj: 金币+4, 翻译EPI+1 2013-06-18 22:05:46
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As a traditional polymorphic binary compound, Vanadium dioxide（VO2）has polymorphs of B, M, R and et ac. The polymorph B has a metastable monoclinic rutile structure, polymorph M has a monoclinic rutile structure and polymorph R has a tetragonal rutile structure. VO2 is a potential function material with broad applications for its unique MTS phase transition characteristic at low temperature and specific optical and electrical properties. This dissertation focused on an one step synthesis of metastable phase VO2 (B) powders under hydrothermal conditions, using NH4VO3 as the resource of vanadium and ethanol as reducing agent. And, this paper studied the phase transition condition from VO2 (B) to VO2 (M) under provided circumstances as well. For the experiment, the means of characterization, such as XRD, SEM, were used to observe the structure and morphology of the products. The experiment was optimized by adjusting the molar ratio of V2O5 powder to ethanol, the temperature, reaction time and pH value of the reaction solution. The experimental results showed that: under hydrothermal method, V2O5 was reduced to pure VO2 (B) by ethanol at 200 ℃ in 24h. When the temperature rose to 240 ℃ and the reaction time was increased to 72 h, a small amount of VO2 (B) was transformed to VO2 (M). In addition, with the increase of temperature and time, the shape of the product particle changed from rod-like to snowflake. |
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