Smaller, quieter, and more economical cooling systems for household air conditioning and refrigeration could come of new discoveries by researchers at the National Institute of Standards and Technology working with scientists from the Beijing University of Technology. They have developed a new alloy — a mix of manganese, iron, phosphorous, and germanium — that is the first near-room-temperature magnetocaloric material. Magnetocalorics heat up when exposed to a magnetic field. If left to cool by radiating away the heat and the magnetic field is removed, their temperature drops again, this time dramatically. Such materials have long been used by industry and science, sometimes to get temperatures down to near absolute zero, but technical and environmental problems have kept them from being employed in households.
The new alloy, unlike previous magnetocalorics, uses no expensive rare metals like gadolinium or dangerous toxins like arsenic. Researchers say its magnetocaloric properties are strong enough to form the basis for cooling systems as efficient as today’s gas-compression technology. Researchers who examined the material with neutron diffraction discovered its crystal structure changes completely when exposed to a magnetic field, accounting for its behavior.
