Anion Order-to-Disorder Transition in Layered Iron Oxyfluoride Sr2FeO3F Single Crystals
Anion Order-to-Disorder Transition in Layered Iron Oxyfluoride Sr2FeO3F Single Crystals
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DOI：
10.1021/cg500484e
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发表时间：
2014-08
影响因子：
3.8
通讯作者：
Y. Tsujimoto;Y. Matsushita;N. Hayashi;K. Yamaura;T. Uchikoshi
中科院分区：
文献类型：
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作者：
Y. Tsujimoto;Y. Matsushita;N. Hayashi;K. Yamaura;T. Uchikoshi
控制金属中心周围混合阴离子的分布是固态化学中长期存在的课题。我们利用高压高温技术成功获得了铁基层状钙钛矿化合物Sr2FeO3F的单晶。在 1300 °C 和 3 GPa 下制备的相在四方空间群 P4/nmm 中结晶，顶部位置的 O/F 原子有序。然而，1800℃的温度和6GPa的压力导致部分O/F位点无序。阴离子无序度为5%，表明阴离子有序排列相当稳健，与完全无序状态的Sr2BO3F（B = Co或Ni）形成鲜明对比。 57Fe穆斯堡尔谱测量显示两相之间的尼尔温度没有太大差异，但在后一种条件下制备的相表现出由O/F位点无序引起的超精细场的准连续分布。我们讨论阴离子有序到无序的机制......
Controlling the distribution of mixed anions around a metal center is a long-standing subject in solid state chemistry. We successfully obtained single crystals of an iron-based layered perovskite compound, Sr2FeO3F, by utilizing a high-pressure and high-temperature technique. The phase prepared at 1300 °C and 3 GPa crystallized in tetragonal space group P4/nmm with O/F atoms at the apical sites being ordered. However, a temperature of 1800 °C and a pressure of 6 GPa resulted in partial O/F site disordering. The degree of anion disordering, which was 5%, showed that the anion-ordered arrangement was quite robust, in sharp contrast to that of Sr2BO3F (B = Co or Ni) with the fully disordered state. 57Fe Mossbauer spectroscopy measurements revealed no large difference in Neel temperatures between the two phases, but the phase prepared under the latter condition exhibited a quasi-continuous distribution of hyperfine fields caused by O/F site disordering. We discuss the mechanism of the anion order-to-disorder...