Magnetocaloric effect and refrigerant capacity in melt-spun Gd–Mn alloys

•The magnetocaloric properties of melt-spun Gd100-x-Mnx (x=0, 5, 10, 15, and 20) alloys were examined.•Lattice parameters, Curie temperature, saturation magnetization (∼260 K), and maximum magnetic entropy change decreases upon alloying Gd with Mn.•The refrigeration capacity initially increases (0≤x≤5) and then decreases (5≤x≤20) upon alloying Gd with Mn.•The near-room temperature magnetocaloric properties of the melt-spun alloys were comparable to few first-order transitions based magnetic refrigerants.

The magnetocaloric properties and microstructure of melt-spun Gd100-xMnx (x=0, 5, 10, 15, and 20 at%) alloys were investigated to explore their potential application as room-temperature magnetic refrigerants. The alloys were composed of nanostructured hexagonal α-Gd phase with grain sizes between 40 and 150 nm. Increasing the Mn content resulted in a decrease in the lattice parameters (a and c) of Gd, suggesting the formation of a substitutional solid solution. The Curie temperature (TC), derived from M–T curves and Arrot plots, decreased monotonically from ∼293 K (melt-spun Gd) to ∼278 K (melt-spun Gd80Mn20). The saturation magnetization at 260 K decreased from ∼108 emu/g (melt-spun Gd) to ∼78 emu/g (melt-spun Gd80Mn20). The peak value of magnetic entropy change, (−ΔSM)max, decreased from ∼8.6 J/kgK for melt-spun Gd to ∼5.9 J/kgK for melt-spun Gd80Mn20 alloy and the refrigeration capacity (RC) initially increased from ∼433 J/kg for melt-spun Gd to ∼452 J/kg for melt-spun Gd95Mn5 and then gradually decreased to ∼321 J/kg for melt-spun Gd80Mn20, for a magnetic field varying from 0 to 5 T. The near-room temperature magnetocaloric properties of melt-spun Gd100-xMnx (0≤x≤20) alloys were found to be comparable to other magnetic refrigerants based on first-order phase transitions.