A New Ceramic Magnetic Regenerator Material for 4 K Cryocoolers

A new class of magnetic regenerator materials for 4 K cryocoolers has been developed. A hexagonal gadolinium oxisulfide Gd2O2S=GO8 has been found to provide a very high volumetric heat capacity of more than 1 J/cm3K at 5.2 K. Polycrystal ceramic GOS particles have been fabricated with diameters between 0.35 mm and 0.45 mm. The achieved smooth surface on the spherical particles and a Vickers hardness of ∼900 make the material very suitable for use in regenerators.