Remarkable Oxygen Intake/Release of BaYMn2O5+未 Viewed from High-Temperature Crystal Structure

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• 作者：Teruki Motohashi ; Taira Takahashi ; Makoto Kimura ; Yuji Masubuchi ; Shinichi Kikkawa ; Yoshiki Kubota ; Yoji Kobayashi ; Hiroshi Kageyama ; Masaki Takata ; Susumu Kitagawa ; Ryotaro Matsuda
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：February 5, 2015
• 年：2015
• 卷：119
• 期：5
• 页码：2356-2363
• 全文大小：384K
• ISSN：1932-7455

文摘

Crystal structure of double-perovskite type BaYMn₂O_5+未 was studied by high-temperature synchrotron X-ray diffraction (SXRD) under precisely controlled oxygen pressure to gain deeper understanding of the remarkable oxygen intake/release capability of this oxide. The in situ SXRD analysis at 750 掳C revealed that this oxide undergoes a distinct structural change upon lowering oxygen pressure, from a slightly oxygen-deficient 鈥溛?= 1鈥?phase (BaYMn₂O_5.89; P(O₂) = 10³ Pa) to an oxygen-vacancy ordered 鈥溛?= 0.5鈥?phase (BaYMn₂O_5.51; P(O₂) = 10 Pa). The BaYMn₂O_5.89 structure (orthorhombic Cmmm) involves statistical distribution of oxygen vacancies within the yttrium plane. Meanwhile, the BaYMn₂O_5.51 structure (orthorhombic Icma) contains arrays of pyramidal MnO₅ and octahedral MnO₆ forming an alternate ordering, which is stabilized by a particular Mn³⁺ orbital ordering with collective displacements of Y³⁺ arrays. Thus, the discontinuous change in the oxygen content can be attributed to the structural reconstruction with oxygen/vacancy redistribution accompanied by yttrium displacement organization.