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Title: Intrinsic magnetic properties of L1{sub 0} FeNi obtained from meteorite NWA 6259

FeNi having the tetragonal L1{sub 0} crystal structure is a promising new rare-earth-free permanent magnet material. Laboratory synthesis is challenging, however, tetragonal L1{sub 0} FeNi—the mineral “tetrataenite”—has been characterized using specimens found in nickel-iron meteorites. Most notably, the meteorite NWA 6259 recovered from Northwest Africa is 95 vol. % tetrataenite with a composition of 43 at. % Ni. Hysteresis loops were measured as a function of sample orientation on a specimen cut from NWA 6259 in order to rigorously deduce the intrinsic hard magnetic properties of its L1{sub 0} phase. Electron backscatter diffraction showed that NWA 6259 is strongly textured, containing L1{sub 0} grains oriented along any one of the three equivalent cubic directions of the parent fcc structure. The magnetic structure was modeled as a superposition of the three orthonormal uniaxial variants. By simultaneously fitting first-quadrant magnetization data for 13 different orientations of the sample with respect to the applied field direction, the intrinsic magnetic properties were estimated to be saturation magnetization 4πM{sub s} = 14.7 kG and anisotropy field H{sub a} = 14.4 kOe. The anisotropy constant K = 0.84 MJ/m{sup 3} is somewhat smaller than the value K = 1.3 MJ/m{sup 3} obtained by earlier researchers from nominally equiatomic FeNi prepared by neutron irradiation accompanied by annealing in a magnetic field,more » suggesting that higher Ni content (fewer Fe antisite defects) may improve the anisotropy. The fit also indicated that NWA 6259 contains one dominant variant (62% by volume), the remainder of the sample being a second variant, and the third variant being absent altogether.« less
Authors:
 [1] ; ; ;  [2] ; ;  [3] ; ;  [4] ;  [5] ;  [6]
  1. MEDA Engineering and Technical Services, Southfield, Michigan 48075 (United States)
  2. Chemical Sciences and Materials Systems Lab, GM R and D Center, Warren, Michigan 48090 (United States)
  3. Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)
  4. Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (United States)
  5. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States)
  6. Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
Publication Date:
OSTI Identifier:
22410152
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ANNEALING; BACKSCATTERING; ELECTRON DIFFRACTION; FCC LATTICES; HYSTERESIS; IRON METEORITES; IRRADIATION; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; MINERALS; NEUTRON FLUENCE; NICKEL; PERMANENT MAGNETS; PHYSICAL RADIATION EFFECTS; RARE EARTHS; TEXTURE