Crystal structure, magnetism and magnetocaloric properties of Mn2−xSn0.5Ga0.5 (x = 0, 0.3, 0.5, 0.8) alloys

Abstract

Magnetic refrigeration based on the magnetocaloric effect has attracted recent attention due to advantages such as high efficiency and environmental friendliness. We have investigated the structural, magnetic and magnetocaloric properties of Mn2−xSn0.5Ga0.5 (x = 0, 0.3, 0.5, 0.8) alloys prepared using arc-melting and melt-spinning techniques with prospects for magnetic refrigeration. The Mn2−xSn0.5Ga0.5 alloys, except for Mn1.2Sn0.5Ga0.5, have a single-phase hexagonal crystal structure. The Mn1.2Sn0.5Ga0.5 alloy also contains a small amount of MnSn2 impurity phase. The Curie temperature and high-field (30 kOe) magnetization at 55 K decrease with increasing Mn concentration from 306 K and 64.1 emu/g (1.07 µB/Mn) for Mn1.2Sn0.5Ga0.5 to 262 K and 46.7 emu/g (0.85 µB/Mn) for Mn2Sn0.5Ga0.5, respectively. The peak values of magnetic entropy change are relatively small with ΔSM,max=1.7 Jkg−1K−1 for Mn1.5Sn0.5Ga0.5 at 30 kOe. Despite this, these materials show considerable relative cooling power (RCP) along with a wide working temperature range near room temperature and negligible magnetic and thermal hysteresis, where Mn1.2Sn0.5Ga0.5 shows a highest RCP of 102.3 Jkg−1 at 30 kOe.