Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates

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• 作者：F. Deganello ; L.F. Liotta ; A. Longo ; M.P. Casaletto and M. Scopelliti
• 关键词：Ce-doped strontium ferrates ; Perovskite-type materials ; Smoldering auto-combustion synthesis ; Octahedral Fe³⁺
• 刊名：Journal of Solid State Chemistry
• 出版年：2006
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：November 2006
• 卷：179
• 期：11
• 页码：3406-3419
• 文件大小：580 K

摘要

Nanostructured perovskite-type Sr_1−aCe_aFeO_3−x, (0a<0.15) powders have been prepared by citrate–nitrate smoldering auto-combustion. Their phase structure and stability, surface and morphological properties, reduction behavior and interaction with oxygen have been investigated by X-ray Powder Diffraction combined with Rietveld Analysis, ⁵⁷Fe M&#xf6;ssbauer and X-ray Photoelectron Spectroscopies, N₂-adsorption method, Temperature Programmed Reduction and Oxidation experiments. Our results reveal that citrate–nitrate auto-combustion method is effective in obtaining single phase Sr_1−aCe_aFeO_3−x. The Sr_1−aCe_aFeO_3−x structure is cubic only for a0.06, while for a<0.06 remains tetragonal. Moreover, for a0.06 after semi-reductive treatment under inert gas, an expanded cubic phase is obtained instead of the brownmillerite-type structure, which is known to have ordered vacancies. Stabilization of octahedral Fe³⁺ by cerium doping appears to be the main factor in determining the structural properties of Sr_1−aCe_aFeO_3−x. The highest oxygen consumption for Ce-doped SrFeO₃ occurs for a