| Autor: |
Saura-Múzquiz M; School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia.; Department of Materials Physics, Universidad Complutense de Madrid, Madrid 28040, Spain., Avdeev M; School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia.; Australian Nuclear Science and Technology Organisation, New Illawarra Rd., Lucas Heights 2234, New South Wales, Australia., Brand HEA; Australian Synchrotron, Australian Nuclear Science and Technology Organisation, 800 Blackburn Road, Clayton 3168, Victoria, Australia., Kennedy BJ; School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia. |
| Abstrakt: |
The structures and magnetic properties of the Os 4+ (5d 4 ) halides K 2 OsCl 6 , K 2 OsBr 6 , Na 2 OsBr 6 , and Na 2 OsBr 6 ·6H 2 O are described. K 2 OsCl 6 and K 2 OsBr 6 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 Na 2 OsBr 6 ·6H 2 O 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. Na 2 OsBr 6 ·6H 2 O and Na 2 OsBr 6 are isostructural with the analogous iridium chlorides, Na 2 IrCl 6 ·6H 2 O and Na 2 IrCl 6 , 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. |
