Solid state materials for magnetic refrigiration: polar intermetallics of main group p-elements and 3d- and 4f-metals as promising magnetocaloric agents

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This grant application is requesting funds for establishing a research program in chemistry of magnetocaloric materials. The research will focus on design, synthesis and characterization of new magnetocaloric materials in which ferromagnetic and structural transitions are coupled. Such materials produce a large temperature response with a change in magnetic field and can be used for refrigeration and air-conditioning. Currently understudied and underutilized, magnetocaloric cooling agents offer better efficiency, simpler mechanical design and are more environmentally friendly than vapor cooling agents used in regular refrigerator units. Progress in this area depends strongly on the discovery of new phases with good stability, high cooling capacity and useful operational temperatures. A key to achieving good magnetocaloric properties is to couple a ferromagnetic ordering to a first-order structural transition; the enthalpy associated with the structural transition enhances the temperature response and increases the cooling efficiency of the material. In this respect, structurally flexible polar intermetallic phases of 4f-, 3d- and p-elements present good opportunities for discovery of new magnetocaloric phases. The research in my group will pursue four distinct directions: - modification of the magnetic LnCo5 phases along the Ln(Co1-xBx)5 compositional lines; - exploration of the magnetic spinel phases; - investigation of the rare-earth rich parts of the ternary Ln-T-Sb and Ln-T-Bi systems (T = Fe, Co and Ni); - study of the transition metal rich parts of the Ln-Co-P and Ln-Ni-P systems.