期刊
INORGANIC CHEMISTRY
卷 60, 期 21, 页码 16652-16657出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.inorgchem.1c02521
关键词
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资金
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Brockhouse Institute for Materials Research by McMaster University
- NSERC
The synthesis and characterization of the double perovskite SrLaLiOsO6, which is isostructural and isoelectronic with SrLaMgReO6, show different magnetic behaviors at low temperatures. SrLaLiOsO6 has a significantly reduced frustration index compared to SrLaMgReO6.
The synthesis and characterization of the double perovskite SrLaLiOsO6 is presented. It is isostructural (P2(1)/n) and isoelectronic (5d(2)) with SrLaMgReO6, which has been reported previously. The cell volumes are the same to within 1.4%: i.e., these perovskites are doppelgangers. In a previous study SrLaMgReO6 showed no sign of spin order to 2 K. New data at lower temperatures disclose a maximum in the dc susceptibility near 1.5 K. As the Curie-Weiss (C-W) temperature (Theta) for this material is -161 K, an enormous frustration index, f approximate to 100, is implied ( f = vertical bar Theta vertical bar/T-ord). On the other hand, SrLaLiOsO6 does not follow the C-W law over the investigated susceptibility range, 2-300 K. Fitting with an added temperature independent term (TIP) gives mu(eff) = 1.96 mu(B), Theta = -102 K, and TIP = 1.01 x 10(-3) emu/mol. A clear zero-field-cooled (ZFC), field-cooled (FC) divergence in the dc data occurs at similar to 10 K, suggesting a much reduced frustration index, f approximate to 10, relative to SrLaMgReO6. The real part of the ac susceptibility data, chi'(max), shows a frequency shift that is consistent with a spin glass ground state according to the Mydosh criterion. Heat capacity data for SrLaLiOsO6 show no sign of a lambda peak at 10 K and a linear dependence on temperature below 10 K, also supporting a spin glass ground state. A spin frozen ground state for SrLaMgReO6 could not be established from chi' data due to a much weaker signal. Nonetheless, the 10-fold difference in f between these doppelganger materials is remarkable. It is possible that the enhanced covalency with the oxide ligands for Os6+ relative to Re5+ plays a major role here. Finally, a comparison with isostructural La2LiReO6 (with a much smaller f approximate to 4) is made and a correlation between the frustration level and the sense of the local distortion of the Re(Os)-O octahedron is pointed out.
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