Free-Spin Dominated Magnetocaloric Effect in Dense Gd3+ Double Perovskites
© 2022 American Chemical Society.
| Veröffentlicht in: | Chemistry of materials : a publication of the American Chemical Society. - 1998. - 34(2022), 7 vom: 12. Apr., Seite 3440-3450 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2022
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| Zugriff auf das übergeordnete Werk: | Chemistry of materials : a publication of the American Chemical Society |
| Schlagworte: | Journal Article |
| Zusammenfassung: | © 2022 American Chemical Society. Frustrated lanthanide oxides with dense magnetic lattices are of fundamental interest for their potential in cryogenic refrigeration due to a large ground state entropy and suppressed ordering temperatures but can often be limited by short-range correlations. Here, we present examples of frustrated fcc oxides, Ba2GdSbO6 and Sr2GdSbO6, and the new site-disordered analogue Ca2GdSbO6 ([CaGd] A [CaSb] B O6), in which the magnetocaloric effect is influenced by minimal superexchange (J 1 ∼ 10 mK). We report on the crystal structures using powder X-ray diffraction and the bulk magnetic properties through low-field susceptibility and isothermal magnetization measurements. The Gd compounds exhibit a magnetic entropy change of up to -15.8 J/K/molGd in a field of 7 T at 2 K, a 20% excess compared to the value of -13.0 J/K/molGd for a standard in magnetic refrigeration, Gd3Ga5O12. Heat capacity measurements indicate a lack of magnetic ordering down to 0.4 K for Ba2GdSbO6 and Sr2GdSbO6, suggesting cooling down through the liquid 4-He regime. A mean-field model is used to elucidate the role of primarily free-spin behavior in the magnetocaloric performance of these compounds in comparison to other top-performing Gd-based oxides. The chemical flexibility of the double perovskites raises the possibility of further enhancement of the magnetocaloric effect in the Gd3+ fcc lattices |
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| Beschreibung: | Date Revised 19.05.2022 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 0897-4756 |
| DOI: | 10.1021/acs.chemmater.2c00261 |