Probing the Defect-Induced Magnetocaloric Effect on Ferrite/Graphene Functional Nanocomposites and their Magnetic Hyperthermia

T. Prabhakaran, R. Udayabhaskar, R. V. Mangalaraja, Saeed Farhang Sahlevani, Rafael M. Freire, Juliano C. Denardin, F. Béron, Kokkarachedu Varaprasad, Miguel Angel Gracia-Pinilla, Marcus Vinicius-Araújo, Andris F. Bakuzis

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7 Scopus citations


Recently, the development of an alternative magnetic refrigerant for the conventional fossil fuels attracts the researchers. We discussed the structural defect-induced magnetocaloric effect (MCE) in Ni0.3Zn0.7Fe2O4/graphene (NZF/G) nanocomposites for the first time. Single-phase spinel ferrite nanocomposites with an average size of 7-11.4 nm were achieved by using the microwave-assisted coprecipitation method. The effect of graphene loading on the structural and magnetism of NZF/G nanocomposites was elaborated. Raman analysis proved that the interface interaction between NZF and graphene yielded different densities of structural defects. In view of magnetism, superparamagnetic NZF nanoparticles showed a magnetic entropy change (-Î"SMmax) of-0.678 Jkg-1 K-1 at 135 K, whereas the NZF/G nanocomposites exhibited superior-Î"SMmax at cryogenic temperatures and the defect-induced MCE change was indeed similar to the ID/IG intensity ratio. The nanocomposites exhibited different magnetic orderings between 5 and 295 K, and it was varying for ID/IG, 1.83 > 1.68 > 1.57 as antiferromagnetic (AFM) > AFM/ferrimagnetic (FiM) > FiM, respectively. Till now, NZF/G nanocomposites showed an inverse MCE of 4.378 Jkg-1 K-1 at 35 K and a refrigerant capacity of 88 Jkg-1 for 40 kOe, which was greater than the ferrites reported so far. Finally, MCE and magnetic hyperthermia were correlated at ambient conditions. These results pave the way for ferrite/graphene nanocomposites for cooling applications.

Original languageEnglish
Pages (from-to)25844-25855
Number of pages12
JournalJournal of Physical Chemistry C
Issue number42
StatePublished - 24 Oct 2019
Externally publishedYes


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