Materials that change temperature in magnetic fields could lead to new refrigeration technologies that reduce the use of greenhouse gases, thanks to new research at the U.S. Department of Energy's Argonne National Laboratory and Ames National Laboratory.
Scientists carrying out X-ray experimentation at the Advanced Photon Source at Argonne the nation's most powerful source of X-rays for research are learning new information about magnetocaloric materials that have potential for environmentally friendly magnetic refrigeration systems.
Magnetic refrigeration is a clean technology that uses magnetic fields to manipulate the degree of ordering (or entropy) of electronic or nuclear magnetic dipoles in order to reduce a material's temperature and allow the material to serve as a refrigerant. New materials for refrigeration based on gadolinium-germanium-silicon alloys display a giant magnetocaloric effect due to unusual coupling between the material's magnetism and chemical structure.
Understanding this coupling is essential to moving this technology from the laboratory to the household. Magnetic refrigeration does not rely on hydrofluorocarbons (HFCs) used in conventional refrigeration systems. HFCs are greenhouse gases that contribute to global climate change when they escape into the atmosphere.
A collaboration between researchers from Argonne and Ames has now revealed key atomic-level information about these new materials that makes clear the role played by the nominally non-magnetic germanium-silicon ions in the giant magnetocaloric effect. In an article published in the June 15 issue of Physical Review Letters, the researchers describe how they used high-brilliance, circularly-polarized X-ray beams at the Advanced Photon Source to probe the magnetism of gadolinium and germanium ions as the material underwent its bond-breaking magneto-structural transition. In addition to the expected strong magnetization of gadolinium io
Contact: Sylvia Carson
DOE/Argonne National Laboratory