Simultaneous optimization of entropy changes and thermal hysteresis in barocaloric compound of Mn3Pt

Abstract

Mn₃Pt metal compounds are promising candidates for barocaloric cooling applications for their high thermal conductivity and pressure sensitivity. However, they are constrained by low entropy change and large thermal hysteresis. This study investigates the effects of doping with carbon (C) and nitrogen (N) and substituting with germanium (Ge) on the structure, as well as the thermal and barocaloric effects of Mn₃Pt. We found that N and C doping significantly reduces the phase transition temperature and improves pressure sensitivity, although at the cost of reduced entropy change. In contrast, Ge substitution increases the phase transition temperature and enhances the entropy change by 123 %, with Mn₃Pt_0.8Ge_0.2 achieving a maximum entropy change of 22.7 J kg⁻¹ K⁻¹. Additionally, defects were introduced to reduce the phase transition nucleation driving force, thereby lowering the thermal hysteresis to 4 K. This work provides a strategy for the simultaneous optimization of entropy change and thermal hysteresis, advancing the development of efficient and tunable barocaloric materials.