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Title: Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles

Abstract

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 additivemore » Au both lowers the chemical ordering temperature and promotes sintering.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [2];  [3]
  1. University of Alabama, Tuscaloosa
  2. ORNL
  3. National Institute of Standards and Technology (NIST)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Flux Isotope Reactor
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1003412
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 8
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ADDITIVES; AGGLOMERATION; ANNEALING; COHERENCE LENGTH; NEUTRON DIFFRACTION; SMALL ANGLE SCATTERING; SILICON; SINTERING; SPIN; SUBSTRATES; X-RAY DIFFRACTION

Citation Formats

Kang, Shishou, Jia, Zhiyong, Zoto, Ilir, Reed, R. C., Nikles, David E., Harrell, J. W., Vemuru, Krishnamurthy V, and Porcar, L. Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles. United States: N. p., 2006. Web. doi:10.1063/1.2165789.
Kang, Shishou, Jia, Zhiyong, Zoto, Ilir, Reed, R. C., Nikles, David E., Harrell, J. W., Vemuru, Krishnamurthy V, & Porcar, L. Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles. United States. doi:10.1063/1.2165789.
Kang, Shishou, Jia, Zhiyong, Zoto, Ilir, Reed, R. C., Nikles, David E., Harrell, J. W., Vemuru, Krishnamurthy V, and Porcar, L. Sun . "Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles". United States. doi:10.1063/1.2165789.
@article{osti_1003412,
title = {Sintering Behavior of Spin-coated FePt and FePtAu Nanoparticles},
author = {Kang, Shishou and Jia, Zhiyong and Zoto, Ilir and Reed, R. C. and Nikles, David E. and Harrell, J. W. and Vemuru, Krishnamurthy V and Porcar, L.},
abstractNote = {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.},
doi = {10.1063/1.2165789},
journal = {Journal of Applied Physics},
number = 8,
volume = 99,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Monodisperse L1{sub 0}-FePt nanoparticles with size ranging from 3 to 8 nm were prepared by the salt-matrix annealing method. It was observed that the annealed particles have high thermal stability - no sintering occurred even when the particles were heated at 1100 C for an hour. This high thermal stability resulted from carbon coating of the particles during salt-matrix annealing as consequence of decomposition of surfactants.
  • The Fe{sub x}Pt{sub 100−x} nanoparticles (NPs) with different nominal atomic rations (30≤x≤80) were synthesized at 700 °C by the sol–gel method. The structure, morphology and magnetic properties of the samples were investigated. When the Fe content in the Fe–Pt alloy NPs was 30 at%, FePt{sub 3} NPs were successfully synthesized. With the increase in Fe content up to 50 at%, it was found that the superlattice reflections (0 0 1) and (1 1 0) appeared, which indicated the formation of the L1{sub 0}-FePt phase. Meanwhile, the FePt{sub 3} fraction was reduced. When the Fe content increased to 60 at%, single-phasemore » L1{sub 0}-FePt NPs were synthesized. The coercivity (Hc), saturation magnetization (Ms) and chemical order parameter S for Fe{sub 60}Pt{sub 40} NPs were as high as 10,200 Oe, 17.567 emu/g and 0.928, respectively. With the further increase of the Fe content to 80 at%, only Fe{sub 3}Pt phase existed and the Hc of the Fe{sub 3}Pt NPs decreased drastically to 360 Oe. - Graphical abstract: Fe{sub 3}Pt, FePt and FePt{sub 3} nanoparticles was obtained by sol–gel method. The effect of iron and platinum content on structural and magnetic properties of the FePt nanoparticles was investigated. Display Omitted - Highlights: • L1{sub 2}-FePt{sub 3}, L1{sub 0}-FePt and L1{sub 2}-Fe{sub 3}Pt NPs were synthesized by sol–gel method. • The chemical order parameter S affects the magnetic properties of the Fe–Pt alloy. • Structural and magnetic properties of the Fe–Pt alloy NPs were studied. • The synthetic route in this study will open up the possibilities of practical use.« less
  • No abstract prepared.