Iridate Li8IrO6: An Antiferromagnetic Insulator

Published

November 15, 2021

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

Pub Type

Journals

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 Li₈IrO₆: An Antiferromagnetic Insulator, Inorganic Chemistry (Accessed December 3, 2024)