Magnetocaloric effect in Gd5Si2Ge2/Gd composite materials

Spark plasma sintering technique has been applied to synthesize composite Gd-x(Gd5Si2Ge2)(1-x) (x=0.3, 0.5, and 0.7) with layer structure using high-purity gadolinium (Gd) metal and Gd5Si2Ge2 alloys. The magnetocaloric effect of the composites was studied by directly measuring adiabatic temperature change (Delta T-ad) with a magnetic-field change of 1.5 T using a homemade magnetocaloric effect measuring apparatus. With increasing x from 0.3 to 0.7, Delta T-ad peak temperature shifted from 286 to 293 K and the peak values of Delta T-ad slowly increased from 1.6 to 2.0 K at a magnetic-field change of 1.5 T. Meanwhile, the Delta T-ad peak of the composite broadened as Gd content was increased. For x=0.7, the composite showed a Delta T-ad ranging from 1.1 to 2.0 K at a magnetic-field change of 1.5 T in a temperature range of 260-300 K, which adapted to work as a room-temperature refrigerant. (C) 2006 American Institute of Physics.