Low Temperature Properties of HoSb, DySb, and GdSb

Materials including rare-earth and Sb compounds were developed as regenerator materials for a 4K GM refrigerator. Sb compounds have a remarkably large peak value of specific heat in the low temperature range. First, the heat capacities, thermal conductivity, and thermal expansion of HoSb, DySb and GdSb, which are anti-ferromagnetic with a large spin value in the low temperature range, were measured. Then, the results of these measurements were used to analyze the problems encountered when Sb compounds were used as the regenerative materials in a GM refrigerator.