Magnetocaloric properties of (Gd1-xErx)3Ru alloys and their composites

We present magnetization, specific heat and magnetocaloric effect results for the compounds (Gd1-xErx)(3)Ru, with x = 0.05, 0.1, 0.2 and 1. As Er concentration increases we observe a significant reduction of the transition temperature from 52 K to 8.1 K and a change from first order ferromagnetic to second order antiferromagnetic behavior. Despite the magnetic arrangement changes, the magnetocaloric potential remains high and a composite formed with these compounds is proposed to achieve temperatures of 20 K starting from nitrogen boiling point. The magnetic entropy variation and adiabatic temperature change of the composite were directly measured presenting a plateau between 20 K and 77 K with values higher than 6 J/kg.K and 3 K respectively for a magnetic field variation of 5 T. (C) 2019 Elsevier B.V. All rights reserved.