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Zeleňák V, Almáši M, Zeleňáková A, Hrubovčák P, Tarasenko R, Bourelly S, Llewellyn P. Large and tunable magnetocaloric effect in gadolinium-organic framework: tuning by solvent exchange. Sci Rep 2019; 9:15572. [PMID: 31666558 PMCID: PMC6821888 DOI: 10.1038/s41598-019-51590-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/23/2019] [Indexed: 12/01/2022] Open
Abstract
Magnetic properties of three variants of MOF-76(Gd), {[Gd(BTC)(H2O)]·G}n (BTC = benzene-1,3,5-tricarboxylate, G = guest molecules) were investigated by static susceptibility, isothermal magnetization and specific heat capacity measurements. In the study we used as synthesized MOF-76(Gd)-DMF (1) (G = DMF = dimethylformamide), containing DMF molecules in the cavity system, compound MOF-76(Gd) (2), activated complex without solvents in the cavities and water exchanged sample MOF-76(Gd)-H2O (3). A pronounced change in the magnetic entropy was found near the critical temperature for all three compounds. It was shown, that magnetic entropy change depends on the solvatation of the MOF. The highest value entropy change, ΔSMpk(T) was observed for compound 2 (ΔSMpk(T) = 42 J kg-1 K-1 at 1.8 K for ΔH = 5 T). The ΔSMpk(T) for the compounds 1, 2 and 3 reached 81.8, 88.4 and 100% of the theoretical values, respectively. This suggests that in compound 3 Gd3+···Gd3+ antiferromagnetic interactions are decoupled gradually, and higher fields promote a larger decoupling between the individual spin centers. The observed entropy changes of compounds were comparable with other magnetic refrigerants proposed for low-temperature applications. To study the magnetothermal effect of 2 (the sample with largest -ΔSMpk), the temperature-dependent heat capacities (C) at different fields were measured. The value of magnetic entropy S obtained from heat capacities (39.5 J kg-1 K-1 at 1.8 K for an applied magnetic field change of 5 T) was in good agreement with that derived from the magnetization data (42 J kg-1 K-1 at 1.8 K).
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Affiliation(s)
- Vladimír Zeleňák
- Institute of Chemistry, Faculty of Science, P.J. Šafárik University in Košice, Moyzesova 11, SK-041 54, Košice, Slovakia.
| | - Miroslav Almáši
- Institute of Chemistry, Faculty of Science, P.J. Šafárik University in Košice, Moyzesova 11, SK-041 54, Košice, Slovakia
| | - Adriána Zeleňáková
- Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice, Park Angelinum 9, SK-040 01, Košice, Slovakia
| | - Pavol Hrubovčák
- Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice, Park Angelinum 9, SK-040 01, Košice, Slovakia
| | - Róbert Tarasenko
- Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice, Park Angelinum 9, SK-040 01, Košice, Slovakia
| | - Sandrine Bourelly
- Aix-Marseille University, CNRS, MADIREL, F-13397, Marseille 20, France
| | - Philip Llewellyn
- Aix-Marseille University, CNRS, MADIREL, F-13397, Marseille 20, France
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