Magnetic and magnetocaloric properties of a foam composite based on substituted La-manganite in a polyurethane matrix

• Published in: Journal of magnetism and magnetic materials Vol. 538; p. 168296
• Main Authors: Salazar-Muñoz, V.E., Palomares-Sánchez, S.A., Betancourt, I., Torres-Castillo, A.A., Cabal Velarde, J.G., Lobo Guerrero, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2021; Elsevier BV
• Subjects: Addition polymerization; Cooling; Curie temperature; Ferromagnetism; Lanthanum; Lanthanum compounds; Magnetic properties; Magnetization curves; Magneto-polymeric composite; Magnetocaloric effect; Manganites; Polyurethane foam; Porous structure; Substituted lanthanum manganite; Substitutes; Substituted lanthanum manganite; Magneto-polymeric composite; Porous structure; Magnetocaloric effect
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2021.168296

•Enhancement of the relative cooling capacity in a porous composite.•Magnetocaloric properties of a polyurethane-manganite composite.•Magnetic properties of manganite embedded into a polyurethane foam.•Increment of the magnetic entropy change by effect of a porous structure. This work deals with the effect that a porous structure causes on the magnetocaloric properties of substituted lanthanum manganite with the formula La0.67Ca0.28Sr0.05MnO3. A composite with a foam structure was fabricated using a polyurethane matrix and embedded manganite particles at three different amounts. The magnetocaloric effect was determined indirectly by mathematical adjustment of the experimental magnetization curves as a function of temperature, according to the phenomenological model proposed by Hamad. Based on the phenomenological parameters, the magnetic entropy change, ΔSm (H, T), was calculated at 1.5 T and 3.0 T. Also, the Curie temperature, the relative cooling power, RCP, the heat capacity, ΔCp, and the order of the ferromagnetic-paramagnetic transition of all the samples were determined. Results show a highlighting increase of the relative cooling power when the manganite particles are dispersed in the polymeric matrix. In addition, the magnetocaloric properties turned out to be a function of the amount of manganite embedded in the matrix. Better results were obtained at a lower manganite content. In all the studied cases, the magnetocaloric properties of the foam composite are better than that of the powder. This behavior is attributable to a change in the interaction state of the manganite particles due to the confinement that they undergo in the polymeric matrix.