Status of the Development of Ceramic Regenerator Materials

This paper describes the status of recent developments of ceramic regenerator materials. First, improvement of the thermal and mechanical properties of Gd2O2S (GOS) regenerator material has been achieved. Since the heat capacity of GOS is very high (> 1 J/cm3), with a γ type peak at 5.2 K, the thermal penetration depth is about 30% smaller than that of HoCu2 below 6 K. Thus, a small particle size (less than 0.3 mm) with a high homogeneity is important for optimization of cooling efficiency. The recent introduction of Hot Isostatic Pressing (HIP) for fabricating GOS particles has been shown to be very effective in increasing the quality. Higher thermal conductivity and a withstanding pressure higher than 5 MPa have been achieved.