On the direct measurement of the adiabatic temperature change of magnetocaloric materials

Abstract

Direct measurement of an adiabatic temperature change in magnetocaloric materials is fundamental to design efficient and eco-friendly magnetocooling devices. This work reports an overview of the measurement principle and the main experimental issues that have to be considered to obtain a reliable characterization of materials. The effect of non-ideal adiabatic conditions, the role of the temperature sensor, and the influence of specific properties of the material are discussed on the basis of finite-difference thermal simulations and specially designed experiments. Two cases are considered in detail: the characterization of thin samples and the measurement of caloric response to fast field changes. Finally, the impact of different measurement protocols is discussed in the case of materials with first-order transitions.