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Comparison of the Crystal Chemistry of Tellurium (VI), Molybdenum (VI), and Tungsten (VI) in Double Perovskite Oxides and Related Materials
Progress in Solid State Chemistry ( IF 12.0 ) Pub Date : 2019-12-01 , DOI: 10.1016/j.progsolidstchem.2019.100251
Ashley V. Flores , Austyn E. Krueger , Amanda J. Stiner , Hailey M. Albert , Travis Mansur , Victoria Willis , Chanel C. Lee , Luis J. Garay , Loi T. Nguyen , Matthew A. Frank , Paris W. Barnes , Allyson M. Fry-Petit

Abstract A comprehensive structural comparison of 56 Te6+-, Mo6+-, and W6+-containing oxides with the double perovskite stoichiometry (A2BB′O6) is presented. This work shows that much like d0 Mo6+- and W6+-containing perovskites, p0 Te6+-containing compositions are strongly affected by the tolerance factor and identities of the A- and B-cations. To make this comparison more complete, the ambient temperature crystal structures of five A2BTeO6 (A = Ca2+, Sr2+, or Ba2+; B = Zn2+ or Cd2+) perovskites were determined via powder diffraction and their vibronic and electronic structures were probed via infrared and diffuse reflectance spectroscopy. The new structural information reported here coupled with a thorough review of relevant literature demonstrates that Te6+, with its sigma bonding preference and lack of allowed orbital mixing gives rise to additional structure types that are not commonly observed in the Mo6+ or W6+ analogues. Analysis of double perovskites containing the hexavalent cations comparing the tolerance factor to the difference in ionic radii of the cations with octahedral coordination is presented. Additionally, examination of the Coulombic repulsions between the B and Te6+ cations plotted as a function of difference in the twelve- and seven-coordinate ionic radii for the A- and B-cations respectively provides new insight on why A2BTeO6 and A2BWO6 (A = B = Sr2+ or Ba2+) adopt perovskite structures with non-cooperative octahedral tilting distortions, while cooperative octahedral distortions are observed when the A and B sites are occupied by smaller cations like Ca2+ and Cd2+.

中文翻译:

双钙钛矿氧化物和相关材料中碲 (VI)、钼 (VI) 和钨 (VI) 的晶体化学比较

摘要 提供了具有双钙钛矿化学计量 (A2BB'O6) 的 56 种含 Te6+-、Mo6+- 和 W6+ 的氧化物的综合结构比较。这项工作表明,与含 d0 Mo6+- 和 W6+ 的钙钛矿非常相似,含 p0 Te6+ 的成分受 A- 和 B- 阳离子的耐受因子和特性的强烈影响。为了使这种比较更加完整,通过粉末衍射确定了五种 A2BTeO6(A = Ca2+、Sr2+ 或 Ba2+;B = Zn2+ 或 Cd2+)钙钛矿的环境温度晶体结构,并通过红外和漫反射探测它们的振动和电子结构光谱学。此处报告的新结构信息以及对相关文献的全面审查表明,Te6+、由于其 sigma 键合偏好和缺乏允许的轨道混合,导致了在 Mo6+ 或 W6+ 类似物中不常见的其他结构类型。对含有六价阳离子的双钙钛矿进行了分析,将耐受因子与八面体配位阳离子的离子半径差异进行了比较。此外,检查 B 和 Te6+ 阳离子之间的库仑排斥力绘制为 A 和 B 阳离子的 12 和 7 坐标离子半径差异的函数,提供了关于为什么 A2BTeO6 和 A2BWO6 (A = B = Sr2+ 或 Ba2+) 采用具有非协同八面体倾斜畸变的钙钛矿结构,而当 A 和 B 位点被较小的阳离子如 Ca2+ 和 Cd2+ 占据时,观察到协同八面体畸变。
更新日期:2019-12-01
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