Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles

Wittig, J. E.; Bentley, James; Lupini, Andrew R; Lukehart, C. M.

Title: Z-STEM of L1_o Ordering in FePt Magnetic Nanoparticles

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Abstract

The L1{sub o} (CuAuI) ordered FePt structure exhibits exceptional magnetic properties with uniaxial-magnetocrystalline anisotropy (K{sub u}) greater than 10{sup 6} ergs/cm3. Chemical synthesis methods can produce monodispersed FePt nanoparticles that have diameters ranging from 3 to 10 nm with a standard deviation of less than 5%. As-synthesized, the FePt nanoparticles are face-centered cubic (FCC) and require annealing at temperatures greater than 550 C for chemical ordering into the L1{sub o} structure. X-ray diffraction (XRD) methods typically characterize the ordering phase transformation by measuring the superlattice peaks. However, since the FePt nanoparticles coarsen during annealing, the larger particles may dominate the XRD data while the smallest particles correspondingly may contribute little to the diffracted intensity. Since recent data suggest that the FePt L1{sub o} ordering transformation is particle-size dependent, the current study employs high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM), also known as atomic-number contrast or Z-STEM, methods to investigate the presence of L1{sub o} order in individual FePt nanoparticles.

Authors:

Wittig, J. E. ^[1]; Bentley, James ^[2]; Lupini, Andrew R ^[2]; Lukehart, C. M. ^[1]

Vanderbilt University
ORNL

Publication Date:: Mon Jan 01 00:00:00 EST 2007

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Shared Research Equipment Collaborative Research Center

Sponsoring Org.:: USDOE Office of Science (SC); Work for Others (WFO)

OSTI Identifier:: 931754

DOE Contract Number:: DE-AC05-00OR22725

Resource Type:: Conference

Resource Relation:: Conference: Microscopy and Microanalysis 2007, Fort Lauderdale, FL, USA, 20070805, 20070809

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; IRON ALLOYS; PLATINUM ALLOYS; ORDER PARAMETERS; NANOSTRUCTURES; MAGNETIC PROPERTIES; PHASE TRANSFORMATIONS; STEM; FePt; nanoparticles; phase transformation; atomic resolution; magnetism

Citation Formats


                    Wittig, J. E., Bentley, James, Lupini, Andrew R, and Lukehart, C. M. Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles.  United States: N. p., 2007. 
        Web.

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                    Wittig, J. E., Bentley, James, Lupini, Andrew R, & Lukehart, C. M. Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles.  United States.

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                    Wittig, J. E., Bentley, James, Lupini, Andrew R, and Lukehart, C. M. 2007.  
        "Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles".  United States.

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@article{osti_931754,

  title        = {Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles},

  author       = {Wittig, J. E. and Bentley, James and Lupini, Andrew R and Lukehart, C. M.},

  abstractNote = {The L1{sub o} (CuAuI) ordered FePt structure exhibits exceptional magnetic properties with uniaxial-magnetocrystalline anisotropy (K{sub u}) greater than 10{sup 6} ergs/cm3. Chemical synthesis methods can produce monodispersed FePt nanoparticles that have diameters ranging from 3 to 10 nm with a standard deviation of less than 5%. As-synthesized, the FePt nanoparticles are face-centered cubic (FCC) and require annealing at temperatures greater than 550 C for chemical ordering into the L1{sub o} structure. X-ray diffraction (XRD) methods typically characterize the ordering phase transformation by measuring the superlattice peaks. However, since the FePt nanoparticles coarsen during annealing, the larger particles may dominate the XRD data while the smallest particles correspondingly may contribute little to the diffracted intensity. Since recent data suggest that the FePt L1{sub o} ordering transformation is particle-size dependent, the current study employs high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM), also known as atomic-number contrast or Z-STEM, methods to investigate the presence of L1{sub o} order in individual FePt nanoparticles.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/931754},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Mon Jan 01 00:00:00 EST 2007},

  month        = {Mon Jan 01 00:00:00 EST 2007}

}

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Title: Z-STEM of L1o Ordering in FePt Magnetic Nanoparticles

Abstract

Citation Formats

Title: Z-STEM of L1_o Ordering in FePt Magnetic Nanoparticles