Solid-State 29Si NMR and Neutron-Diffraction Studies of Sr0.7K0.3SiO2.85 Oxide Ion Conductors

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• 作者：Jungu Xu ; Xiaoming Wang ; Hui Fu ; Craig M. Brown ; Xiping Jing ; Fuhui Liao ; Fengqi Lu ; Xiaohui Li ; Xiaojun Kuang ; Mingmei Wu
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：July 7, 2014
• 年：2014
• 卷：53
• 期：13
• 页码：6962-6968
• 全文大小：336K
• ISSN：1520-510X

文摘

K/Na-doped SrSiO₃-based oxide ion conductors were recently reported as promising candidates for low-temperature solid-oxide fuel cells. Sr_0.7K_0.3SiO_2.85, close to the solid-solution limit of Sr_1鈥?i>xK_xSiO_3鈥?.5x, was characterized by solid-state ²⁹Si NMR spectroscopy and neutron powder diffraction (NPD). Differing with the average structure containing the vacancies stabilized within the isolated Si₃O₉ tetrahedral rings derived from the NPD study, the ²⁹Si NMR data provides new insight into the local defect structure in Sr_0.7K_0.3SiO_2.85. The Q¹-linked tetrahedral Si signal in the ²⁹Si NMR data suggests that the Si₃O₉ tetrahedral rings in the K-doped SrSiO₃ materials were broken, forming Si₃O₈ chains. The Si₃O₈ chains can be stabilized by either bonding with the oxygen atoms of the absorbed lattice water molecules, leading to the Q¹-linked tetrahedral Si, or sharing oxygen atoms with neighboring Si₃O₉ units, which is consistent with the Q³-linked tetrahedral Si signal detected in the ²⁹Si NMR spectra.