Anion Order-to-Disorder Transition in Layered Iron Oxyfluoride Sr2FeO3F Single Crystals

详细信息    查看全文

• 作者：Yoshihiro Tsujimoto ; Yoshitaka Matsushita ; Naoaki Hayashi ; Kazunari Yamaura ; Tetsuo Uchikoshi
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：September 3, 2014
• 年：2014
• 卷：14
• 期：9
• 页码：4278-4284
• 全文大小：367K
• ISSN：1528-7505

文摘

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 掳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 掳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 M枚ssbauer spectroscopy measurements revealed no large difference in N茅el 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 transition observed in related oxyfluoride perovskites.