Effect of doping elements on the thermal stability of transition alumina

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• 作者：Rossignol ; Sylvie ; Kappenstein ; Charles
• 关键词：Alumina ; Thermal stability ; Sol gel process ; Doping elements
• 刊名：The International Journal of Inorganic Materials
• 出版年：2001
• 期刊代码：40_14666049
• 类别：ms
• 出版时间：January, 2001
• 卷：3
• 期：1
• 页码：51-58
• 文件大小：408 K

摘要

The thermal stability of porous transition alumina at high temperature is a crucial challenge for several applications. To delay the θ to α-alumina transition temperature (1180°C), the synthesis by sol–gel method and the introduction of doping element as nitrate salt M(NO₃)_x (M=Ba, Mg, Pr, La and Ce) have been investigated. Over three preparation procedures, the introduction of the doping element through the sol–gel process gave the higher BET surface area. Additional thermal analysis and powder X-ray diffraction studies have shown that only a few amount (1 mol percent) of doping element is sufficient to increase the θ→α-Al₂O₃ phase transition temperature up to 1315°C. The most promising samples are (Al₂O₃)_0.98Ba_0.02 and (Al₂O₃)_0.99Pr_0.01. Even after 5 h at 1200°C, they maintain a rather good specific area (32 m²/g) in relation with the incomplete and very slow transformation of θ into α-alumina.