Hydrogenation-induced variation in crystal structure and heat capacity of magnetic regenerative material Er3Ni

In order to analyze the influence of hydrogenation on magnetic regenerative material Er 3 Ni, the structures of Er 3 Ni and its hydrides Er 3 NiH x are tested by X-ray diffraction (XRD), and their magnetic properties and heat capacities are measured by a magnetic property measurement system (MPMS) and by a physical property measurement system (PPMS), respectively. The results show that different crystal structures can be formed by the hydrogenation at 293 K, while the Er 3 NiH x does not go through magnetic transition above 2 K. The Er 3 NiH x exhibits different specific heat features with that of original compound Er 3 Ni, which could be attributed to the absence of magnetic transition and other effects caused by hydrogenation. The insertion of hydrogen atoms can lead to a larger specific heat than that of Er 3 Ni in some certain temperature range. Keywords Cryocoolers E. Regenerators C. Heat capacity Hydrogenation