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Iridate Li8IrO6: An Antiferromagnetic Insulator

Published

Author(s)

Callista M. Skaggs, Peter E. Siegfried, Chang-Jong Kang, Craig Brown, Fu Chen, Lu Ma, Steven N. Ehrlich, Yan Xin, Mark Croft, Wenqian Xu, Saul H. Lapidus, Nirmal J. Ghimire, Xiaoyan Tan

Abstract

A poltcrystalline iridate, Li8IrO6, material was prepared via heating Li2O and IrO2 starting materials in a sealed quartz tube at 650 °C for 48 hours. The structure was determined from Rietveld refinement of room temperature powder neutron diffraction. Li8IrO6 adopts the non-polar space group R3 with Li atoms occupying the tetrahedral and octahedral sites, which is supported by the electron diffraction and solid-state 7Li-NMR. This results in a crystal structure consisting of LiO4 tetrahedral layers alternating with mixed IrO6 and LiO6 octahedral layers along the crystallographic c axis. The +4 oxidation state of Ir4+ was confirmed by near-edge X-ray absorption spectroscopy. In-situ synchrotron X-ray diffraction study of Li8IrO6 indicates that the sample is stable to 1000 °C and exhibits no structural transitions on heating. Magnetic measurements suggest long-range antiferromagnetic order with TN = 4 K in Li8IrO6, which is corroborated by heat capacity measurement. The localized small effective moment, µeff (Ir) = 1.21 µB, and insulating character indicate that Li8IrO6 is a correlated insulator. First-principle calculations support the non-polar crystal structure and reveal Li8IrO6 as a Slater-type as opposed to a Mott-type insulator.
Citation
Inorganic Chemistry
Volume
60
Issue
22

Keywords

antiferromagnetic , neutron diffraction , Slater-type Insulator , crystallography

Citation

Skaggs, C. , Siegfried, P. , Kang, C. , Brown, C. , Chen, F. , Ma, L. , Ehrlich, S. , Xin, Y. , Croft, M. , Xu, W. , Lapidus, S. , Ghimire, N. and Tan, X. (2021), Iridate Li<sub>8</sub>IrO<sub>6</sub>: An Antiferromagnetic Insulator, Inorganic Chemistry (Accessed May 18, 2024)

Issues

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Created November 14, 2021, Updated November 29, 2022