title: A universal metric for ferroic energy materials.
abstract: After almost 20 years of intensive research on magnetocaloric effects near room temperature, magnetic refrigeration with first-order magnetocaloric materials has come close to real-life applications. Many materials have been discussed as potential candidates to be used in multicaloric devices. However, phase transitions in ferroic materials are often hysteretic and a metric is needed to estimate the detrimental effects of this hysteresis. We propose the coefficient of refrigerant performance, which compares the net work in a reversible cycle with the positive work on the refrigerant, as a universal metric for ferroic materials. Here, we concentrate on examples from magnetocaloric materials and only consider one barocaloric experiment. This is mainly due to lack of data on electrocaloric materials. It appears that adjusting the field-induced transitions and the hysteresis effects can minimize the losses in first-order materials.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.
authors.affiliation: Fundamental Aspects of Materials and Energy, Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands e.h.bruck@tudelft.nl.
authors.forename: Ekkes
authors.identifier: 0000-0002-5063-3338
authors.initials: E
authors.lastname: Brück
authors.affiliation: Fundamental Aspects of Materials and Energy, Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands.
authors.forename: Hargen
authors.initials: H
authors.lastname: Yibole
authors.affiliation: BASF Nederland B.V., Strijkviertel 61, 3454 PK De Meern, The Netherlands.
authors.forename: Lian
authors.initials: L
authors.lastname: Zhang
keywords: Fe2P; coefficient of refrigerant performance; magnetocaloric; reversible cycle