Effect of Cu substitution on the type of magnetic phase transition and magnetocaloric effect in the ErCo2-xCux compounds

In this paper, the crystal structure, magnetic phase transition and magnetocaloric properties of the ErCo2-xCux (x = 0.12, 0.24, 0.36 and 0.48) compounds have been investigated in detail. All of the compounds crystallize in the C15 cubic Laves structure (MgCu2-type) with the Fd-3 m space group. The substitution of Cu for Co is accompanied by an increase of the Curie temperature T-c from 31.5 K to 68 K for x varying from 0.12 to 0.48. The nature of the magnetic phase transition, determined by the results of the Arrott plots and Landau theory, changed from a first order to a second order in the ErCo2-xCux compounds with the Cu content increasing. The isothermal entropy change -delta S-M is calculated according to isothermal magnetization measurements using Maxwell's relation. For an applied magnetic field change of 0-5 T, the -delta S-M decreased from 30 J kg(-1) K-1 for x = 0.12 to 10.9 J kg(-1) K-1 for x = 0.48, whereas the working temperature range became wider due to that the magnetic transition type changed from a first order to a second order, which is a benefit for the application of the magnetic refrigeration. The corresponding refrigerant capacity RC values are 270.8 J kg(-1), 194.1 J kg(-1), 261.8 J kg(-1) and 264.8 J kg(-1), respectively. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this paper, the crystal structure, magnetic phase transition, and magnetocaloric properties of the ErCo2-xCux (x = 0.12, 0.24, 0.36, and 0.48) compounds were investigated. The substitution of Cu for Co increased the Curie temperature and changed the magnetic phase transition type from first order to second order, resulting in an increased refrigerant capacity.