Regenerator Material of Rare Earth Nitride (Ho_xEr_1-xN) for a 4 K-GM Cryocooler

Abstract

We synthesized Ho_xEr_1-xN (x = 0, 0.25, 0.5) sphere materials using the hot isostatic pressing (HIP) method and studied the regenerator performance by measuring the cooling power obtained by a 4 K-GM cryocooler loaded with them. At 4.2 K, we observed a cooling power higher, though slightly, than loaded with HoCu₂ spheres, which have been the standard commercial regenerator material. A higher cooling power, 25% increment to the observed, is expected by removing the defects occurring in the present samples which have degraded the performance.