C o Fe 2 O 4 nanostructures with high coercivity

J. S. Jung, J. H. Lim, K. H. Choi, S. L. Oh, Y. R. Kim, S. H. Lee, D. A. Smith, K. L. Stokes, L. Malkinski, C. J. O'Connor

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (Co Fe2 O4). We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600 °C for 2 h in Ar gas forming arrays of cobalt ferrite nanowires inside the AAT. The morphology of the ferrite before and after annealing was observed using a field-emission scanning electron microscope. The crystallographic structure of the nanowires was analyzed using x-ray diffraction and transmission electron microscopy. The magnetization was measured by a superconducting quantum interference device. The coercivity of the annealed ferrite in the form of nanowires is significantly larger than that of the separate ferrite nanoparticles in the pores. This effect is due to the clustering of nanoparticles when the organic solvent is removed by high-temperature annealing as well as an improvement in the crystallininty of the ferrite by reduction of defects. The Faraday spectra of the nanowires were measured before and after annealing. A significant peak was observed at 725 nm. The nanowire/AAT composite material had a Verdet constant of 0.1 min (Oe cm) at the peak. It is important to mention that not only the properties but also the form of the material-a regular array of pillars-may be important for microelectronic or information storage applications.

Original languageEnglish
Article number10F306
JournalJournal of Applied Physics
Volume97
Issue number10
DOIs
Publication statusPublished - 2005 May 15

Fingerprint

coercivity
ferrites
nanowires
cobalt
templates
aluminum oxides
nanoparticles
annealing
porosity
magnetic materials
permanent magnets
microelectronics
embedding
field emission
x ray diffraction
electron microscopes
interference
magnetization
vacuum
transmission electron microscopy

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Jung, J. S., Lim, J. H., Choi, K. H., Oh, S. L., Kim, Y. R., Lee, S. H., ... O'Connor, C. J. (2005). C o Fe 2 O 4 nanostructures with high coercivity. Journal of Applied Physics, 97(10), [10F306]. https://doi.org/10.1063/1.1852851
Jung, J. S. ; Lim, J. H. ; Choi, K. H. ; Oh, S. L. ; Kim, Y. R. ; Lee, S. H. ; Smith, D. A. ; Stokes, K. L. ; Malkinski, L. ; O'Connor, C. J. / C o Fe 2 O 4 nanostructures with high coercivity. In: Journal of Applied Physics. 2005 ; Vol. 97, No. 10.
@article{118d0bfd9046486daf37b6a5ed5092ac,
title = "C o Fe 2 O 4 nanostructures with high coercivity",
abstract = "Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (Co Fe2 O4). We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600 °C for 2 h in Ar gas forming arrays of cobalt ferrite nanowires inside the AAT. The morphology of the ferrite before and after annealing was observed using a field-emission scanning electron microscope. The crystallographic structure of the nanowires was analyzed using x-ray diffraction and transmission electron microscopy. The magnetization was measured by a superconducting quantum interference device. The coercivity of the annealed ferrite in the form of nanowires is significantly larger than that of the separate ferrite nanoparticles in the pores. This effect is due to the clustering of nanoparticles when the organic solvent is removed by high-temperature annealing as well as an improvement in the crystallininty of the ferrite by reduction of defects. The Faraday spectra of the nanowires were measured before and after annealing. A significant peak was observed at 725 nm. The nanowire/AAT composite material had a Verdet constant of 0.1 min (Oe cm) at the peak. It is important to mention that not only the properties but also the form of the material-a regular array of pillars-may be important for microelectronic or information storage applications.",
author = "Jung, {J. S.} and Lim, {J. H.} and Choi, {K. H.} and Oh, {S. L.} and Kim, {Y. R.} and Lee, {S. H.} and Smith, {D. A.} and Stokes, {K. L.} and L. Malkinski and O'Connor, {C. J.}",
year = "2005",
month = "5",
day = "15",
doi = "10.1063/1.1852851",
language = "English",
volume = "97",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "10",

}

Jung, JS, Lim, JH, Choi, KH, Oh, SL, Kim, YR, Lee, SH, Smith, DA, Stokes, KL, Malkinski, L & O'Connor, CJ 2005, 'C o Fe 2 O 4 nanostructures with high coercivity', Journal of Applied Physics, vol. 97, no. 10, 10F306. https://doi.org/10.1063/1.1852851

C o Fe 2 O 4 nanostructures with high coercivity. / Jung, J. S.; Lim, J. H.; Choi, K. H.; Oh, S. L.; Kim, Y. R.; Lee, S. H.; Smith, D. A.; Stokes, K. L.; Malkinski, L.; O'Connor, C. J.

In: Journal of Applied Physics, Vol. 97, No. 10, 10F306, 15.05.2005.

Research output: Contribution to journalArticle

TY - JOUR

T1 - C o Fe 2 O 4 nanostructures with high coercivity

AU - Jung, J. S.

AU - Lim, J. H.

AU - Choi, K. H.

AU - Oh, S. L.

AU - Kim, Y. R.

AU - Lee, S. H.

AU - Smith, D. A.

AU - Stokes, K. L.

AU - Malkinski, L.

AU - O'Connor, C. J.

PY - 2005/5/15

Y1 - 2005/5/15

N2 - Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (Co Fe2 O4). We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600 °C for 2 h in Ar gas forming arrays of cobalt ferrite nanowires inside the AAT. The morphology of the ferrite before and after annealing was observed using a field-emission scanning electron microscope. The crystallographic structure of the nanowires was analyzed using x-ray diffraction and transmission electron microscopy. The magnetization was measured by a superconducting quantum interference device. The coercivity of the annealed ferrite in the form of nanowires is significantly larger than that of the separate ferrite nanoparticles in the pores. This effect is due to the clustering of nanoparticles when the organic solvent is removed by high-temperature annealing as well as an improvement in the crystallininty of the ferrite by reduction of defects. The Faraday spectra of the nanowires were measured before and after annealing. A significant peak was observed at 725 nm. The nanowire/AAT composite material had a Verdet constant of 0.1 min (Oe cm) at the peak. It is important to mention that not only the properties but also the form of the material-a regular array of pillars-may be important for microelectronic or information storage applications.

AB - Nanometer-sized ferrite magnetic materials are the subject of intense research interest due to their potential applications in high-density magnetic information storage. One of the most explored ferrite materials is the cobalt ferrite (Co Fe2 O4). We have synthesized cobalt ferrite nanowires using cobalt ferrite nanoparticles in a porous anodic alumina template (AAT). The process of embedding ferrimagnetic particles into the pores was assisted by the magnetic field of a permanent magnet placed in vacuum directly under the substrate. Particles synthesized in the template were subsequently annealed at 600 °C for 2 h in Ar gas forming arrays of cobalt ferrite nanowires inside the AAT. The morphology of the ferrite before and after annealing was observed using a field-emission scanning electron microscope. The crystallographic structure of the nanowires was analyzed using x-ray diffraction and transmission electron microscopy. The magnetization was measured by a superconducting quantum interference device. The coercivity of the annealed ferrite in the form of nanowires is significantly larger than that of the separate ferrite nanoparticles in the pores. This effect is due to the clustering of nanoparticles when the organic solvent is removed by high-temperature annealing as well as an improvement in the crystallininty of the ferrite by reduction of defects. The Faraday spectra of the nanowires were measured before and after annealing. A significant peak was observed at 725 nm. The nanowire/AAT composite material had a Verdet constant of 0.1 min (Oe cm) at the peak. It is important to mention that not only the properties but also the form of the material-a regular array of pillars-may be important for microelectronic or information storage applications.

UR - http://www.scopus.com/inward/record.url?scp=84856154897&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84856154897&partnerID=8YFLogxK

U2 - 10.1063/1.1852851

DO - 10.1063/1.1852851

M3 - Article

AN - SCOPUS:84856154897

VL - 97

JO - Journal of Applied Physics

JF - Journal of Applied Physics

SN - 0021-8979

IS - 10

M1 - 10F306

ER -

Jung JS, Lim JH, Choi KH, Oh SL, Kim YR, Lee SH et al. C o Fe 2 O 4 nanostructures with high coercivity. Journal of Applied Physics. 2005 May 15;97(10). 10F306. https://doi.org/10.1063/1.1852851