Evolution of Fe Crystallographic Sites from Barium Hexaaluminate to Hexaferrite

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• 作者：Yanyan Zhu ; Xiaodong Wang ; Guotao Wu ; Yanqiang Huang ; Yan Zhang ; Junhu Wang ; Tao Zhang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：January 12, 2012
• 年：2012
• 卷：116
• 期：1
• 页码：671-680
• 全文大小：745K
• 年卷期：v.116,no.1(January 12, 2012)
• ISSN：1932-7455

文摘

The substituted metal ions in the hexaaluminate structure are regarded as active centers, but their very limited substituted content prevents the obtainment of higher activity. Fe-substituted hexaaluminates exceptionally overcome such a limit. In this paper, we have studied the Fe crystallographic sites in BaFe_xAl_12鈥?i>xO₁₉ (x = 1鈥?2) and proposed the unique mechanism of stabilization of Fe ions in hexaaluminate structure at a high substitution level by employment of Rietveld refinement and ⁵⁷Fe M枚ssbauer spectroscopy. When x = 1鈥?, the site occupancy of Fe³⁺ in both 尾_I-Al₂O₃ and newly formed magnetoplumbite phases was kept constant, and the increased Fe³⁺ ions were accommodated by the increased amount of magnetoplumbite phase. When x = 5鈥?2, the site occupancy of Fe³⁺ in the magnetoplumbite phase continuously increased, and thus the increased Fe³⁺ ions were accommodated by the magnetoplumbite structure. BaFe_xAl_12鈥?i>xO₁₉ catalysts exhibited different N₂O decomposition properties under conventional furnace heating and microwave heating modes.