Structural and magnetic studies of Fe-implanted α-Al2O3

Alves, E.; Machargue, C. J.; Silva, R.C; Jesus, Carolina; Conde, O.; Silva, R.C. da; Soares, J.C.

doi:10.1016/s0257-8972(00)00578-8

Cited by 23 publications

(5 citation statements)

References 8 publications

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“…3. The formation of a-Fe precipitates elongated in the implanted plane coincides with the previous TEM observations by McHargue et al [8,9]. The last three nonmagnetic (paramagnetic) components (g-Fe, Fe 2þ I and Fe 2þ II ) were also found in Fe-implanted a-Al 2 O 3 samples with lower doses up to 1.0 Â 10 17 ions/cm 2 .…”

Section: Resultssupporting

confidence: 89%

Conversion Electron M�ssbauer Study on Iron-Implanted ?-Al2O3 with Applied Magnetic Fields

Wakabayashi

Hirai

Toriyama

et al. 2002

phys. stat. sol. (a)

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Conversion electron Mö ssbauer spectroscopy with applied magnetic fields up to 0.4 T was used to study aggregation states of iron atoms in an a-Al 2 O 3 single crystal implanted with 57 Fe + ions at a dose of 1.5 Â 10 17 ions/cm 2 . Consistent fits to all the spectra were achieved with five components for the iron states: spherical fine a-Fe particles that exhibit superparamagnetic relaxation, oblate ellipsoidal a-Fe particles exhibiting collective magnetic excitations, g-Fe-like paramagnetic clusters, and two kinds of ferrous oxides. From the analysis of hyperfine field distributions of the component subspectra, particle-size distributions were obtained for the two a-Fe components. The average diameter of the superparamagnetic a-Fe particles was found to be about 3.5 nm, while that for the oblate ellipsoidal a-Fe particles was about 6.2 nm with a dimensional ratio (major axis/minor axis) of about 1.35, which suggests an anisotropic evolution of the precipitated a-Fe during the implantation.

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Section: Resultssupporting

confidence: 89%

Conversion Electron M�ssbauer Study on Iron-Implanted ?-Al2O3 with Applied Magnetic Fields

Wakabayashi

Hirai

Toriyama

et al. 2002

phys. stat. sol. (a)

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“…[45][46][47][48][49] Implantation at elevated temperatures ͑240°C͒ has also been investigated, 44,50 but to a lesser extent. These studies have shown that ␣-Fe nanoparticles are formed by annealing implanted Al 2 O 3 in a reducing environment.…”

Section: Implantation Of Fe Only or Pt Onlymentioning

confidence: 99%

Oriented ferromagnetic Fe-Pt alloy nanoparticles produced in Al2O3 by ion-beam synthesis

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Withrow

Sorge

et al. 2003

Journal of Applied Physics

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Oriented Fe1−xPtx nanoparticles have been formed in single-crystal Al2O3 host matrices by the sequential implantation of Fe and Pt ions followed by thermal annealing. For x in the range of ∼35–55 at. % Pt, these nanoparticles are in the chemically ordered tetragonal L10 structure of FePt and appear to be fully ordered. The nanoparticles are ferromagnetic, and the magnetic coercivity is a strong function of the alloy composition, reaching values in excess of 20 kOe for x∼45%. The crystallographic orientation and morphology of the nanoparticles are strongly dependent on the implantation conditions. Under certain implantation conditions, a buried amorphous layer can be formed in the Al2O3 matrix which crystallizes during annealing giving rise to the formation of an interconnected network of large FePt particles with a single orientation. Oriented nanoparticles of Fe3Pt and FePt3 were also synthesized. The Fe3Pt and FePt3 particles have the ordered, cubic L12 structure with an order parameter of 0.5–0.8; and these particles also exhibit ferromagnetic behavior. The magnetic and structural properties of the Fe1−xPtx nanoparticles are compared to and contrasted with those of nanoparticles of Fe and Pt in Al2O3 that were also formed by ion-beam synthesis. Evidence for Al incorporation into the nanoparticles is also presented.

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“…Some metallic nanocrystals, such as Au, Al, Fe, Y, Ag, formed by ion implantation have been studied in Al 2 O 3 host crystals. [6][7][8][9] There are no reports on metallic Ni nanoparticles formation induced by ion implantation in Al 2 O 3 single crystals. In this letter, the charge states, structure and optical properties of metallic Ni nanoparticles in Ni-implanted Al 2 O 3 crystals were studied by using x-ray photoelectron spectroscopy ͑XPS͒, transmission electron microscopy ͑TEM͒, and optical spectroscopy, respectively.…”

mentioning

confidence: 99%

Optical properties of metallic nanoparticles in Ni-ion-implanted α-Al2O3 single crystals

Zhu

et al. 2004

Applied Physics Letters

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64 keV Ni ion implantation was performed at room temperature up to a dose of 1ϫ10 17 cm Ϫ2 in ␣-Al 2 O 3 single crystals. The charge states, structure, and optical properties of metallic embedded Ni nanoparticles were studied by using x-ray photoelectron spectroscopy ͑XPS͒, transmission electron microscopy, and optical spectroscopy, respectively. XPS analysis showed that implanted Ni ions are mainly in charge state of metallic Ni 0. Nanoparticles distributed from the surface to 30 nm below the surface were observed in a high-angle annular dark-field image. The size of nanoparticles ranges from 1 to 5 nm in diameter. A high-resolution electron microscopy image indicated the Ni-implanted area had been entirely amorphized. A new broad absorption band centered at 400 nm appeared in the optical absorption spectrum of the as-implanted crystal, due to surface plasma resonance of Ni nanoparticles. We did not find any emission band in the as-implanted sample under a Xe lamp excitation wavelength of 250-430 nm in a spectrophotometer.

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Structural and magnetic studies of Fe-implanted α-Al2O3

Cited by 23 publications

References 8 publications

Conversion Electron M�ssbauer Study on Iron-Implanted ?-Al2O3 with Applied Magnetic Fields

Conversion Electron M�ssbauer Study on Iron-Implanted ?-Al2O3 with Applied Magnetic Fields

Oriented ferromagnetic Fe-Pt alloy nanoparticles produced in Al2O3 by ion-beam synthesis

Optical properties of metallic nanoparticles in Ni-ion-implanted α-Al2O3 single crystals

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