Age stability of La(Fe,Si) ₁₃ hydrides with giant magnetocaloric effects

Abstract

Abstract The Curie temperatures ( T C ) of La 0.7 Ce 0.3 Fe 13‐ x ‐ y Mn x Si y compounds that are hydrogenated to saturation are raised to near room temperature. The age stability was investigated for the fully hydrogenated La 0.7 Ce 0.3 Fe 11.5‐ x Mn x Si 1.5 compounds. This result indicates that the H content will slowly decrease in the hydrides, leading to a decrease in T C . However, no age splitting is observed after the hydrides are held at room temperature for two years, indicating the excellent age stability of the hydrides. Further structural analysis by neutron diffraction shows that Mn atoms preferentially substitute Fe in the 96i sites. The T C of La 0.7 Ce 0.3 Fe 11.55‐ y Mn y Si 1.45 hydrides can be adjusted to the desired working temperature by regulating Mn content based on the linear relationship between T C and Mn content. Moreover, the La 0.7 Ce 0.3 Fe 11.55‐ y Mn y Si 1.45 hydrides exhibit a giant magnetic entropy change of 15 J·kg −1 ·K −1 under a low magnetic field change of 0−1 T. As a result, the giant magnetocaloric effect, linearly adjustable T C , and excellent age stability make the La 0.7 Ce 0.3 Fe 11.55‐ y Mn y Si 1.45 hydrides be one of the ideal candidates for room temperature magnetic refrigerants.