ZnTaO2N: Stabilized High-Temperature LiNbO3-type Structure

详细信息    查看全文

• 作者：Yoshinori Kuno ; Cédric Tassel ; Koji Fujita ; Dmitry Batuk ; Artem M. Abakumov ; Kazuki Shitara ; Akihide Kuwabara ; Hiroki Moriwake ; Daichi Watabe ; Clemens Ritter ; Craig M. Brown ; Takafumi Yamamoto ; Fumitaka Takeiri ; Ryu Abe ; Yoji Kobayashi ; Katsuhisa Tanaka ; Hiroshi Kageyama
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：138
• 期：49
• 页码：15950-15955
• 全文大小：416K
• ISSN：1520-5126

文摘

By using a high-pressure reaction, we prepared a new oxynitride ZnTaO₂N that crystallizes in a centrosymmetric (R3̅c) high-temperature LiNbO₃-type structure (HTLN-type). The stabilization of the HTLN-type structure down to low temperatures (at least 20 K) makes it possible to investigate not only the stability of this phase, but also the phase transition to a noncentrosymmetric (R3c) LiNbO₃-type structure (LN-type) which is yet to be clarified. Synchrotron and neutron diffraction studies in combination with transmission electron microscopy show that Zn is located at a disordered 12c site instead of 6a, implying an order–disorder mechanism of the phase transition. It is found that the closed d-shell of Zn²⁺, as well as the high-valent Ta⁵⁺ ion, is responsible for the stabilization of the HTLN-type structure, affording a novel quasitriangular ZnO₂N coordination. Interestingly, only 3% Zn substitution for MnTaO₂N induces a phase transition from LN- to HTLN-type structure, implying the proximity in energy between the two structural types, which is supported by the first-principles calculations.