Structure and Properties of Ir-Containing Oxides with Large Spin–Orbit Coupling: Ba2In2‿i>xIrxO5+δ

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• 作者：Joshua Flynn ; Jun Li ; Arthur W. Sleight ; Arthur P. Ramirez ; M. A. Subramanian
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：March 21, 2016
• 年：2016
• 卷：55
• 期：6
• 页码：2748-2754
• 全文大小：546K
• ISSN：1520-510X

文摘

In this work, the solid solution series Ba₂In_2–xIr_xO_5+δ (x = 0–1.4, 2) was synthesized, and its structural, magnetic, and charge-transport properties were measured. With increasing Ir content, three transitions in the room-temperature structure were observed: orthorhombic to tetragonal to cubic to a monoclinic distortion of a hexagonal BaTiO₃ structure. Neutron diffraction shows Ba₂In_1.6Ir_0.4O_5.4 to be cubic and Ba₂InIrO₆ to be monoclinic, the latter contrary to previously published X-ray diffraction refinements. Magnetization measurements show Curie–Weiss behavior for x = 0.2–0.6, which arises from nearly 50:50 ratio of Ir(V) and Ir(VI). To our knowledge, this is the first time Ir(VI) has been stabilized with standard solid-state methods under ambient conditions. The electrical resistivity measurements show all the compounds studied are semiconducting and that resistivity decreases with increasing Ir content, suggesting the proximity to a metal–insulator transition. A sign reversal in the high-temperature Seebeck coefficient is observed indicating both electron and hole charge transport.