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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]

Table-like magnetocaloric effect is an important requirement for obtaining high efficiency performance in magnetic refrigeration that uses Ericsson cycle. Magnetic and magnetocaloric properties of Ho 36 Co 48 Al 16 alloy, carefully selected from multiphase region of the ternary Ho-Co-Al system, have been studied. The multiphasic alloy exhibits three magnetic phase transitions spread over a wide temperature range. Suitable distribution of phase proportions and respective magnetic entropy changes result in the broadening of the overall peak magnetic entropy change of the alloy. Table-like magnetocaloric effect is obtained with magnetic entropy change of 8.5 J/kg K and large refrigerant capacity of 525 J/kg under applied magnetic field change of 0–5 T. At field change of 0–2 T, the magnitude of the magnetic entropy change plateau is 2.9 J/kg K with refrigerant capacity of 180 J/kg. The table-like feature and the competitive refrigerant capacity and applied magnetic field change values make the multiphase alloy a practical magnetic refrigerant for efficient low temperature cooling applications that employ the Ericsson cycle, even under permanent magnets. [ABSTRACT FROM AUTHOR]