Table-like magnetocaloric effect and large refrigerant capacity in Gd₆₅Mn₂₅Si₁₀-Gd composite materials for near room temperature refrigeration

Amorphous Gd₆₅Mn₂₅Si₁₀ as well as crystalline Gd have technologically significant Curie temperature and large magnetic entropy change. Two types of composite materials Gd₆₅Mn₂₅Si₁₀-Gd were fabricated: laminating Gd sheets and amorphous Gd₆₅Mn₂₅Si₁₀ ribbons (multilayer composite) and hot pressing a mixture of amorphous Gd₆₅Mn₂₅Si₁₀ thin ribbons, Gd particles and a small amount of Sn powders (bulk composite). A table-like magnetocaloric effect (MCE) in a wide, commercially useful, temperature span of 73 K (220 K-293 K) were observed in these composites. The values of full-width at half maximum of (−ΔS_M) − T plots (ΔT_FWHM) and enhanced refrigerant capacity (RC) for the multilayer and bulk composites are 212 K, 724 J/kg, and 248 K, 617 J/kg, respectively, for a field of 5 T. Large ΔT_FWHM and RC values and the table-like (−ΔS_M)^max feature suggest that both multilayer and bulk Gd₆₅Mn₂₅Si₁₀-Gd composites can meet the requirements of different magnetic refrigeration based on Ericsson-cycle.