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With the intention to explore excellent magnetocaloric materials, the intermetallic compound GdPd was synthesized by arc melting and heat treatment. The microstructure, magnetic and magnetocaloric properties of the intermetallic compound of GdPd were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the physical property measurement system (PPMS). A large reversible magnetocaloric effect is observed in GdPd accompanied by a second order magnetic phase transition from paramagnetism to ferromagnetism at ∼39 K. The paramagnetic Curie temperature (θp) and the effective magnetic moment (μeff) are determined to be 34.7 K and 8.12 μB/Gd, respectively. The maximum entropy change ( | Δ S M Max | ) and the relative cooling power (RCP) under a field change of 5 T are estimated to be 20.14 J/(kg·K) and 433 J/kg, respectively. The giant reversible magnetocaloric effects (both the large ΔSM and the high RCP) together with the absence of thermal and field hysteresis make the GdPd compound an attractive candidate for low-temperature magnetic refrigeration.

The structural, magnetic and magnetocaloric properties of Gd7Pd3- x Fe x compounds with x = 0, 0.2 and 0.4 were investigated. Rietveld refinement of X-ray powder diffraction shows that all the investigated samples are single phase and crystallize in a hexagonal structure with the space group P63mc. The lattice parameters (a, b and c), and the cell volume (v) decrease with the increase of Fe content in Gd7Pd3- x Fe x , mainly because of the difference in atomic radius between Fe and Pd. Magnetization versus temperature in a magnetic applied field of 0.05 T shows that Gd7Pd3- x Fe x displays a paramagnetic (PM) – ferromagnetic (FM) transition with the Curie temperature T C decreasing from 336 K for x = 0.0 to 319 K for x = 0.4. Under a field change of 0 to 5 T, the maximum values of the magnetic entropy change ( | Δ S M m a x | ) $\left( {|{\rm{\Delta }}S_M^{max}|} \right)$ are 5.09 J kg−1 K−1, 4.89 J kg−1 K−1, and 4.46 J kg−1 for x = 0, 0.2, and 0.4, and the corresponding relative cooling powers (RCP) amount to 387.6 J Kg−1, 357.2 J · Kg−1, and 385.5 J Kg−1, respectively. The stable magnetocaloric effect and refrigeration capacity near room temperature reveal that the Gd7Pd3- x Fe x compounds may be considered as refrigerants for magnetic refrigeration.

Isothermal section of Fe-Gd-Pd ternary system at 873 K has been established by means of x-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscope (SEM) with energy disperse x-ray spectroscopy (EDS) in backscattered electron imaging modes. The isothermal section consists of 14 single-phase regions, 25 two-phase regions, and 12 three-phase regions. At 873 K, no ternary compound was found and the binary inermetallic compounds Gd3Pd and Fe23Gd6 are not stable, whereas the compound Fe23Gd6 decomposes into compounds Fe17Gd2 and Fe3Gd. The XRD and the SEM/EDS analysis show that there is almost no solubility of Gd in the FePd and FePd3 phases, and the solubilities of Pd in Fe17Gd2, Fe3Gd and Fe2Gd and Fe in GdPd2, α-Gd3Pd4 and Gd3Pd2 are all less than 1 at.%. Meanwhile, the solubilities of Fe in GdPd3, α-GdPd and Gd7Pd3 are determined to be as high as 1.37, 5.31, and 4.18 at.% Fe, respectively.

Magnetic transitional behaviors and the magnetocaloric effect of the intermetallic compound Pr7Pd3 have been studied. A second-order metamagnetic transition between ferromagnetic and paramagnetic states was observed with a Curie temperature (T C) of 14.9 K. The paramagnetic Curie temperature (𝜃 p) and the effective magnetic moment (μ eff) were investigated and determined to be 5.1 K and 3.43 μ B/Pr, respectively. A reversible magnetocaloric effect was observed in this compound originated from the magnetic phase transition. For a magnetic field change of 0–5 T, the maximum magnetic entropy change − ΔS M reached 5.5 J kg− 1 K− 1, and the corresponding value of refrigerant capacity was estimated to be about 65 J kg− 1 with no thermal and field hysteresis loss.