Various samples of the solid solution Gd2NixCu2-xMg were synthesized from the elements in sealed tantalum ampoules in an induction furnace. All members crystallize with the tetragonal Mo2FeB2 type structure, space group P4/mbm, and they were characterized on the basis of Guinier powder patterns and energy dispersive X-rays analyses. The lattice parameters decrease with increasing nickel content in a Vegard-like manner. The Gd2NixCu2-xMg samples show Curie Weiss behavior with slightly higher magnetic moment values than the theoretical one for a free Gd3+ ion. The substitution of copper by nickel has a drastic influence on the magnetism and magnetic ordering temperature. For Gd2Ni0.5Cu1.5Mg a temperature induced FM -> AFM order-to-order transition was observed, whereas Gd2Ni1.0Cu1.0Mg is a metamagnet with H-Cr of about 8 kOe at 5 K. For both compounds, a large reversible magnetocaloric effect (MCE) near their ordering temperatures occurs. The values of the maximum magnetic entropy change -Delta S-M(max) reach 9.5 and 11.4 J kg(-1) K-1 for the field change of 5 T with no obvious hysteresis loss around 65 K for Gd2Ni0.5Cu1.5Mg and Gd2Ni1.0Cu1.0Mg, respectively. The corresponding relative cooling power with 688 and 630 J kg(-1) is relatively high as compared to other MCE materials in that temperature range. These results indicate that Gd2NixCu2-xMg could be a promising system for magnetic refrigeration at temperatures below liquid N-2. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3466775]
Bibliographical noteThe information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Polymer and Materials Chemistry (LTH) (011001041)
Subject classification (UKÄ)
- Chemical Sciences