Mechanochemical preparation, sintering aids and hybrid microwave sintering in the proton conductor Sr_0.02La_0.98Nb_1-xV_xO_4-未, x聽=聽0, 0.15

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• 作者：A.D. Brandã ; o^a ; I. Antunes^a ; J.R. Frade^a ; J. Torre^b ; S.M. Mikhalev^b ; D.P. Fagg^b ; ^duncan@ua.pt
• 关键词：LaNbO4 ; Proton conductor ; Hybrid microwave sintering ; Mechanochemical reaction ; Sintering aids ; Scheelite/Fergusonite
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：April, 2012
• 卷：37
• 期：8
• 页码：7252-7261
• 文件大小：1042 K

摘要

Mechanochemical preparation of Sr_0.02La_0.98Nb_1-xV_xO_4-未 was demonstrated for values of x聽=聽0 and 0.15. Crystallinity could be improved by calcining at 1073聽K. On cooling, the high temperature scheelite phase was retained to room temperature. Several novel sintering additives for LaNbO₄ materials have been tested. The most successful were Cu₃Nb₂O₈ and CuV₂O₆, which reduced the temperature of maximum shrinkage rate to temperatures 鈭?173聽K. The additive CuV₂O₆ was shown to increase densification and promote grain growth. A mechanosynthesised sample of Sr_0.02La_0.98Nb_0.85V_0.15O_4-未聽+聽2聽mol%CuV₂O₆ could be densified to 鈭?90%that of the theoretical by hybrid microwave sintering at 1168聽K for 5聽min. The scheelite phase in this material was retained to room temperature, against the normal thermodynamic tendency. Impedance spectroscopy in wet and dry, nitrogen and oxygen atmospheres suggested that the bulk conductivity of this material is unaffected by the sintering aid, whereas the grain boundary conductivity was impaired and exhibited n-type conductivity behaviour, characteristic of the additive. The concentration of this promising additive should be reduced in further work.