4K-GM Cryocooler Performance and Thermal Conductivity of Ho x Er 1-x N

Ho x Er 1-x N ( x =0.25, 0.5, 0.75) samples were synthesized by nitriding of Ho x Er 1-x alloy bars and their thermal conductivity κ were measured. The measured κ values were comparable to those of stainless steel and Er 3 Ni. Ho 0.5 Er 0.5 N showed the highest κ of the present three samples. The thermal diffusivity calculated from the κ and the specific heat indicates that Ho 0.5 Er 0.5 N is a very promising regenerator material for the cryocoolers. The electrical resistivity ρ was also measured as a function of temperature.