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The effects of Co substitution on the structure, magnetic properties, and magnetocaloric effect of Gd 3 Ru 1− x Co x (0.05 ≤  x  ≤ 0.20) alloys have been investigated by X-ray diffraction and magnetization measurements. The Curie temperatures varied between 60 K and 92 K with Co substitution for Ru. With an applied magnetic field change ( ΔH ) of 50 kOe, the maximum values of magnetic entropy change (−Δ S M ) were determined to be 25.8, 23.1, 19.4, and 10.8 J/kg K for compositions with x  = 0.05, 0.10, 0.15, and 0.20, respectively. The corresponding refrigeration capacities ( RCs ) for the alloys were reasonably large and calculated to be 495, 475, 467, and 517 J/kg. The magnetic phase transitions in the Gd 3 Ru 1− x Co x (0.05 ≤  x  ≤ 0.15) alloys are of first-order. In the Gd 3 Ru 0.80 Co 0.20 , the first-order magnetic phase transition disappears and the transition is broadened hence it increases in RC . The high −Δ S M values and accompanying large RC s for the Gd 3 Ru 1− x Co x (0.05 ≤  x  ≤ 0.20) alloys qualify them as potential candidates for magnetic refrigeration applications near liquid nitrogen temperature. [ABSTRACT FROM AUTHOR]

This paper presents the structure, magnetic properties, and magnetocaloric effect of the polycrystalline compound GdNiAl 2 . Powder X-ray diffraction (XRD) measurement and Rietveld refinement revealed that GdNiAl 2 alloy is CuMgAl 2 -type phase structure with about 1 wt% GdNi 2 Al 3 secondary phase. Magnetic measurements suggest that the compound is ferromagnetic and undergoes a second-order phase transition near 28 K. The maximum value of magnetic entropy change reaches 16.0 J/kg K for an applied magnetic field change of 0–50 kOe and the relative cooling power was 6.4×10 2 J/kg. It is a promising candidate as a magnetocaloric material working near liquid hydrogen temperature (~20 K) exhibiting large relative cooling power. [ABSTRACT FROM AUTHOR]