Table-like magnetocaloric effect in the Gd-Co-Al alloys with multi-phase structure

Abstract

Two sorts of Gd-Co-Al ternary alloys of multi-phase structure with table-like magnetocaloric effect (MCE) suitable for the ideal Ericsson cycle have been developed. One is prepared by arc-melting Gd53Co19Al28 with the resulting alloy composed of Gd2Al, Gd2Co2Al, and GdCo0.74Al1.26 crystalline phases and the other is synthesized by suck-casting Gd52.5Co16Al31 which has a glassy structure and crystalline phases of Gd2Al and Gd2Co2Al. Metamagnetic transition of antiferromagnetic Gd2Al phase near 50 K and ferromagnetic transitions of Gd2Co2Al, GdCo0.74Al1.26, and the glassy phase near 80 K result in the occurring of table-like magnetocaloric effect with magnitude of ∼7 J/kg K over the temperature range from 47.5 K to 77.5 K for a magnetic field variation of 0 to 50 kOe. The fitting reproduces the temperature dependence of magnetic entropy change of samples and the results suggest that the magnetocaloric response of Gd2Al phase in the ternary alloys have been improved, which is crucial for the composite alloys to obtain table-like magnetocaloric effect.