A-site K-doped lanthanum manganite nanocrystalline La0.67Ba0.33MnO3 for room-temperature micro-scale magnetic cooling.
In: Journal of Alloys & Compounds, Jg. 976 (2024-03-05), S. N.PAG
Online
academicJournal
Zugriff:
Bulk nanocrystalline La 0.67 Ba 0.33− x K x MnO 3 (with x = 0, 0.05, 0.1, and 0.2) manganites have been prepared by the modified sol-gel method (Pechini). The single-phase rhombohedral crystal structure with the R-3c (no. 167) space group was verified by X-ray diffraction (XRD) and sustained by Rietveld refinement. As follows from the results of XRD structural analyses, the increase in K-doping triggers an increase in the distortion of the MnO 6 octahedra, which eventually causes the narrowing of the e g bandwidth. Mn is in a mixed valence state of Mn4+/Mn3+ as inferred by X-ray photoelectron spectroscopy. Magnetic measurements confirm that the Curie temperature decreases from 348 K for La 0.67 Ba 0.33 MnO 3 to 316 K for La 0.67 Ba 0.13 K 0.20 MnO 3. The increasing of the Mn4+ ion concentration at the B-site sublattice and A-site ionic disorder (σ 2) breaks up the double exchange interaction between the Mn3+ and Mn4+ ions. The ferromagnetic to paramagnetic second-order magnetic phase transition at T C is also confirmed by electron paramagnetic resonance. According to magnetic field-dependent magnetization isotherms at different temperatures, La 0.67 Ba 0.13 K 0.20 MnO 3 shows a relatively large magnetocaloric effect (1400 mJ cm−3 K−1 at 316 K under 5 T applied magnetic field), which raises the possibility of using this material for room-temperature micro-scale magnetic cooling. [Display omitted] • The modified Pechini method was used to prepare La 0.67 Ba 0.33−x K x MnO 3 material. • Enhanced magnetocaloric properties at 316 K were found for LBK20. • LBK20 shows a relatively large magnetocaloric effect (1400 mJ cm−3 K−1 under 5 T). • LBK20 is proposing for room-temperature micro-scale magnetic cooling. • The K doping induces the increase of the MnO 6 octahedral distortion. [ABSTRACT FROM AUTHOR]
Titel: |
A-site K-doped lanthanum manganite nanocrystalline La0.67Ba0.33MnO3 for room-temperature micro-scale magnetic cooling.
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Autor/in / Beteiligte Person: | Oumezzine, Marwène ; Rostas, Arpad Mihai ; Bocirnea, Amelia Elena ; Hlil, El Kebir ; Galca, Aurelian Catalin |
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Zeitschrift: | Journal of Alloys & Compounds, Jg. 976 (2024-03-05), S. N.PAG |
Veröffentlichung: | 2024 |
Medientyp: | academicJournal |
ISSN: | 0925-8388 (print) |
DOI: | 10.1016/j.jallcom.2023.173257 |
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