ESTUDO DAS PROPRIEDADES MAGNÉTICAS E MAGNETOCALÓRICAS DOS COMPÓSITOS METÁLICOS Dy-Pt-In e Gd-Pt-In

Abstract

This study presents the synthesis of metallic alloy composites based on Dy-Pt-In and Gd-Pt-In, followed by characterization through X-ray diffraction (XRD), Scanning Electron microscopy (SEM) magnetization, and specific heat measurements. XRD and SEM analysis revealed that the Dy-Pt-In composite consists of DyPtIn, DyPt and DyPt2In phases. Similarly, the Gd-Pt-In composite comprises GdPtIn and GdPt phases. Magnetic properties analysis indicates that both composites exhibit the magnetic transitions corresponding to the crystalline phases present in each material. The Dy composite displays two consecutive ferromagnetic transitions at 32.5 K and 23 K, and an antiferromagnetic transition at 7.5 K, which undergoes a metamagnetic phase transition to the ferromagnetic state upon applying a magnetic field, as demonstrated by specific heat data. Magnetocaloric properties analysis revealed that the three consecutive magnetic transitions extend the magnetocaloric effect (MCE) over a wide temperature range between 2.5 and 57 K for the Dy-Pt-In composite. Although the two ferromagnetic transitions in the Gd-Pt-In composite are relatively close, they are sufficiently broad to promote a significant MCE between 6.0 and 89 K. The maximum values obtained for magnetic entropy change are similar for both composites (6.3 and 6 J/kg. K at ΔH = 50 kOe). However, the relative cooling power is 47% higher in the Gd composite (~327 J/kg) compared to the Dy composite (~221 J/kg). The synthesis and characterization of the metallic composites in this study present promising results for applications in magnetic systems, especially in the context of the magnetocaloric effect. These results highlight the importance of developing composites with magnetic systems, since a material with optimized properties for technological application can be obtained by combining the individual magnetic properties of two or more metallic compounds.