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Production of Giant magnetocaloric Substances Using Commercially Available Raw Materials

Ames Laboratory

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Technology Marketing SummaryThe giant magnetocaloric material Gd5(SixGe1-x)4, useful for various types of refrigeration applications, from liquifaction of helium (4K) to room temperature air conditioning and climate control, has just become more cost effective with the development of this new method for utilizing commercially available Gd to produce it.DescriptionThis new method allows for cost effective production of Gd5(SixGe1-x)4 samples of 1 kilogram or more, which have improved magnetocaloric porperties over material produced by othe methods. (The magnetocaloric effect is approximately 25% better than the first reported values (Physical Review Letters, June 1997) for the Gd5(Si2Ge2) which was prepared in 10-20g quantities by arc melting using high purity Ames Laboratory Gd metal).BenefitsThe lower cost will dramatically improve the commercial viability of magnetic refrigeration technologies, which are environmentally friendly and efficient. No commercial method is currently available to use commercial Gd metal to produce Gd5(Si2Ge2) in large quantities and with high magnetocaloric effect.Applications and IndustriesApplications exist anywhere there is need for freezing, heating, or cooling. Industries which produce cryogenics systems; supermagnets; and HVAC systems for homes, vehicular transports and other applications will be interested in this technology.Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 6,589,366
Method of making active magnetic refrigerant, colossal magnetostriction and giant magnetoresistive materials based on Gd-Si-Ge alloys
Method of making an active magnetic refrigerant represented by Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 alloy for 0.ltoreq.x.ltoreq.1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.
Ames Laboratory 07/08/2003
Patent 7,114,340
Method of making active magnetic refrigerant materials based on Gd-Si-Ge alloys
An alloy made of heat treated material represented by Gd.sub.5(Si.sub.xGe.sub.1-x).sub.4 where 0.47.ltoreq.x.ltoreq.0.56 that exhibits a magnetic entropy change (-.DELTA.S.sub.m) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.
Ames Laboratory 10/03/2006
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To: Stacy Joiner<>