Structural and Magnetic Properties of Some Vacancy-Ordered Osmium Halide Perovskites

Matilde Saura-Múzquiz; Maxim Avdeev; Helen E A Brand; Brendan J Kennedy

doi:10.1021/acs.inorgchem.2c02171

Structural and Magnetic Properties of Some Vacancy-Ordered Osmium Halide Perovskites

Inorg Chem. 2022 Oct 10;61(40):15961-15972. doi: 10.1021/acs.inorgchem.2c02171. Epub 2022 Sep 26.

Authors

Matilde Saura-Múzquiz^{1

2}, Maxim Avdeev^{1

3}, Helen E A Brand⁴, Brendan J Kennedy¹

Affiliations

¹ School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia.
² Department of Materials Physics, Universidad Complutense de Madrid, Madrid 28040, Spain.
³ Australian Nuclear Science and Technology Organisation, New Illawarra Rd., Lucas Heights 2234, New South Wales, Australia.
⁴ Australian Synchrotron, Australian Nuclear Science and Technology Organisation, 800 Blackburn Road, Clayton 3168, Victoria, Australia.

PMID: 36153995
DOI: 10.1021/acs.inorgchem.2c02171

Abstract

The structures and magnetic properties of the Os⁴⁺ (5d⁴) halides K₂OsCl₆, K₂OsBr₆, Na₂OsBr₆, and Na₂OsBr₆·6H₂O are described. K₂OsCl₆ and K₂OsBr₆ have a cubic vacancy-ordered double perovskite structure but undergo different symmetry-lowering structural phase transitions upon cooling associated with a combination of the relative size of the ions and differences in their chemical bonding. The structure of Na₂OsBr₆·6H₂O has been determined for the first time and the thermal stability of this has been established using a combination of in situ diffraction and TGA. Na₂OsBr₆·6H₂O and Na₂OsBr₆ are isostructural with the analogous iridium chlorides, Na₂IrCl₆·6H₂O and Na₂IrCl₆, and dehydration proceeds via different intermediate phases. The magnetic moments of four compounds display a Kotani-like behavior consistent with a J_eff = 0 ground state; however, the magnetic susceptibility measurements reveal unusual low temperature properties indicative of a weak magnetic ground state.