Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles

Journal Article · Sun Jan 01 04:00:00 EST 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2165789· OSTI ID:1003412

Kang, Shishou ^[1]; Jia, Zhiyong ^[1]; Zoto, Ilir ^[1]; Reed, R. C. ^[1]; Nikles, David E. ^[1]; Harrell, J. W. ^[1]; Vemuru, Krishnamurthy V ^[2]; Porcar, L. ^[3]

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1. University of Alabama, Tuscaloosa
2. ORNL
3. National Institute of Standards and Technology (NIST)

FePt and [FePt]{sub 95}Au{sub 5} nanoparticles with an average size of about 4 nm were chemically synthesized and spin coated onto silicon substrates. Samples were subsequently thermally annealed at temperatures ranging from 250 to 500 C for 30 min. Three-dimensional structural characterization was carried out with small-angle neutron scattering (SANS) and small-angle x-ray diffraction (SAXRD) measurements. For both FePt and [FePt]{sub 95}Au{sub 5} particles before annealing, SANS measurements gave an in-plane coherence length parameter a = 7.3 nm, while SAXRD measurements gave a perpendicular coherence length parameter c = 12.0 nm. The ratio of c/a is about 1.64, indicating the as-made particle array has a hexagonal close-packed superstructure. For both FePt and FePtAu nanoparticles, the diffraction peaks shifted to higher angles and broadened with increasing annealing temperature. This effect corresponds to a shrinking of the nanoparticle array, followed by agglomeration and sintering of the nanoparticles, resulting in the eventual loss of positional order with increasing annealing temperature. The effect is more pronounced for FePtAu than for FePt. Dynamic coercivity measurements show that the FePtAu nanoparticles have both higher intrinsic coercivity and higher switching volume at the same annealing temperature. These results are consistent with previous studies that show that additive Au both lowers the chemical ordering temperature and promotes sintering.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003412
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 99; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ADDITIVES
AGGLOMERATION
ANNEALING
COHERENCE LENGTH
NEUTRON DIFFRACTION
SILICON
SINTERING
SMALL ANGLE SCATTERING
SPIN
SUBSTRATES
X-RAY DIFFRACTION