Preparation of a High Density Complex Type Magnetic Mixture of RAl2 System for Ericsson Magnetic Refrigerator and Its Fundamental Characteristics

A complex type magnetic mixture in the RAl2 system (where R denotes a rare earth ion) for Ericsson type magnetic refrigerators, is investigated. Previously, the authors reported on the magneto-caloric effects of a stoichiometric RAl2 system, and concluded that this system is a promising candidate for use as Ericsson type magnetic refrigerant in the temperature range above 10 K. In this paper, a method for preparing a complex type RAl2 magnetic system, consisting of a high-density mixture of components on a grain-size scale, is described. This system was found to have the characteristics desired in an Ericsson type refrigerant, including a nearly temperature-independent magnetic entropy change ¿SM, and a high thermal conductivity.