MnAs and MnFeP1−xAsx-based magnetic refrigerants: a review

Abstract

This paper presents a comparative analysis of MnAs and MnFeP1−xAsx family and its alloys from magnetic refrigeration perspective. A thorough literature review was undertaken and to the best of authors knowledge, all samples (∼100 samples) with their Curie temperature (Tc) in the range 260–340 K have been reported. For contrastive analysis, samples have been grouped based on their structural and experimental conditions such as magnetic field and sample composition etc. For comparative analysis, all variables of magnetocaloric effect (MCE), e.g., Tc, magnetic entropy change (), adiabatic temperature change (ΔTad) and relative cooling power (RCP) have been considered with calculated missing variables, wherever possible. The first objective of this paper was to perform a comparative analysis of different fabrication variables (e.g., particle size, shape, morphology, chemical composition, structure, purity of starting materials, homogeneity, annealing, and synthesis methods) on the overall MCE properties of the aforementioned family. In addition, the best fabrication practices for further improvement in MCE properties are proposed. The second objective was to observe different material’s doping (e.g., Cr, Si, Ge, B) in hysteresis loss mitigation and MCE properties enhancement. Best doping materials were suggested for the compositions, which were displaying optimum MCE properties for further MCE enhancement. Lastly, but most importantly, to propose a high performing magnetic refrigerant by: (1) shortlisting a composition with optimum MCE properties; (2) further enhancement in MCE through adopting best fabrication processes for the said magnetic refrigerant; (3) suggesting best doping material for hysteresis loss mitigation and MCE enhancement; and most importantly (4) fabricating the proposed magnetic refrigerant as a nanostructure; thus, improving MCE properties through broadening of Tc curve.