Abstract
In the paper we present and discuss magnetic properties of the Gd(Ni~1–x~ Fe__~x~__)~3~ crystalline compounds and their ball‐milled powders in a context of the magnetocaloric effect (MCE). Moreover, based on the obtained results, powders and composites with non‐magnetic (Cu) and magnetic (Fe) additions were prepared. Magnetic quantities such as the Curie temperature, the saturation magnetization and the MCE (as a magnetic entropy change) were determined for all examined samples. In the case of the bulk crystalline compounds a partial substitution of Ni by Fe atoms causes a decrease of the saturation magnetization as well as the MCE and an increase of the Curie temperature. Samples with x ranging from 0.1 to 0.15 show the best potential for room‐temperature refrigeration. Pulverization of the tested compounds leads to formation of flake‐like grains with thickness less than 1 μm. Such grinding causes a decrease of the Curie temperature (by about 10 K) as well as the MCE (by about 50%) in a comparison with the crystalline samples. In the case of the composite with magnetic addition an enhancement of the MCE was observed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)