Synthesis and Structural Studies of the Transition-Metal-Doped Rh Perovskites LaMn0.5Rh0.5O3 and LaCu0.5Rh0.5O3

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• 作者：Jimmy Ting ; Brendan J. Kennedy ; Zhaoming Zhang ; Maxim Avdeev ; Bernt Johannessen ; Ling-Yun Jang
• 刊名：Chemistry of Materials
• 出版年：2010
• 出版时间：March 9, 2010
• 年：2010
• 卷：22
• 期：5
• 页码：1640-1646
• 全文大小：882K
• 年卷期：v.22,no.5(March 9, 2010)
• ISSN：1520-5002

文摘

The two orthorhombic perovskites LaMn_0.5Rh_0.5O₃ and LaCu_0.5Rh_0.5O₃ have been characterized using X-ray absorption near edge structure (XANES) measurements and powder synchrotron X-ray and neutron diffraction. The Mn and Rh in LaMn_0.5Rh_0.5O₃ are essentially trivalent and disordered onto the same crystallographic site. The absence of an appreciable Jahn−Teller (JT) distortion of the BO₆ octahedra is a consequence of this disorder and large magnitude of the octahedral tilting. XANES measurements show that the Rh in LaCu_0.5Rh_0.5O₃ has a valence state of around +3.5 as a consequence of extensive charge delocalization between the Cu and Rh cations, that are also disordered onto a single site. These two effects combine to further reduce the distortion of the octahedra in LaCu_0.5Rh_0.5O₃ relative to that of LaMn_0.5Rh_0.5O₃.