Neutron scattering and magnetic studies of ferrihydrite nanoparticles
Abstract
Magnetic properties of twoline ferrihydrite (FeOOD{center_dot}nD{sub 2}O) nanoparticles with an average size {approx_equal}4 nm are investigated using neutron scattering and magnetometry. Comparison of the neutron scattering and xray diffraction patterns identifies the (002) peak at Q=1.3 Aa{sup 1} as predominantly magnetic. The intensity of this peak, measured from 10 to 450 K, decreases almost linearly with temperature until 350 K, becoming temperature independent above 350 K. From this, T{sub N}{approx_equal}350 K is identified to be the ordering temperature of the core spins of the nanoparticles. The width of the line is temperature independent, yielding a magnetic coherence length(approx =)particle size. The temperature variations (5300 K) of the initial susceptibility {chi} for the fieldcooled (FC) and zerofieldcooled (ZFC) cases yield a peak at T{sub p}(m){approx_equal}65 K, below which {chi}(FC)>{chi}(ZFC). For T>T{sub p}(m), the variation of {chi}{sup 1} vs T is analyzed in terms of the model of ElHilo et al., involving particlesize distribution and interparticle interactions, and substantial interparticle interactions are inferred. Following the observations in ferritin, the field dependence of the magnetization M for T>T{sub p}(m) is analyzed in terms of the modified Langevin variation: M=M{sub o}L({mu}{sub p}H/kT)+{chi}{sub a}H, where {mu}{sub p} is the magnetic moment/particle. The fit at 100more »
 Authors:

 Department of Physics, West Virginia University, Morgantown, West Virginia 265066315 (United States)
 NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 208998562 (United States)
 Publication Date:
 OSTI Identifier:
 20215333
 Resource Type:
 Journal Article
 Journal Name:
 Physical Review. B, Condensed Matter and Materials Physics
 Additional Journal Information:
 Journal Volume: 61; Journal Issue: 5; Other Information: PBD: 1 Feb 2000; Journal ID: ISSN 10980121
 Country of Publication:
 United States
 Language:
 English
 Subject:
 36 MATERIALS SCIENCE; IRON HYDRIDES; NEUTRON DIFFRACTION; MAGNETIC PROPERTIES; XRAY DIFFRACTION; MAGNETIZATION; TEMPERATURE RANGE 00000013 K; TEMPERATURE RANGE 00130065 K; TEMPERATURE RANGE 00650273 K; TEMPERATURE RANGE 04001000 K; TEMPERATURE RANGE 02730400 K; SPIN; NEEL TEMPERATURE; MAGNETIC SUSCEPTIBILITY; PARTICLE SIZE; MAGNETIC MOMENTS; FERRIMAGNETIC MATERIALS; EXPERIMENTAL DATA; THEORETICAL DATA
Citation Formats
Seehra, M S, Babu, V S, Manivannan, A, and Lynn, J W. Neutron scattering and magnetic studies of ferrihydrite nanoparticles. United States: N. p., 2000.
Web. doi:10.1103/PhysRevB.61.3513.
Seehra, M S, Babu, V S, Manivannan, A, & Lynn, J W. Neutron scattering and magnetic studies of ferrihydrite nanoparticles. United States. doi:10.1103/PhysRevB.61.3513.
Seehra, M S, Babu, V S, Manivannan, A, and Lynn, J W. Tue .
"Neutron scattering and magnetic studies of ferrihydrite nanoparticles". United States. doi:10.1103/PhysRevB.61.3513.
@article{osti_20215333,
title = {Neutron scattering and magnetic studies of ferrihydrite nanoparticles},
author = {Seehra, M S and Babu, V S and Manivannan, A and Lynn, J W},
abstractNote = {Magnetic properties of twoline ferrihydrite (FeOOD{center_dot}nD{sub 2}O) nanoparticles with an average size {approx_equal}4 nm are investigated using neutron scattering and magnetometry. Comparison of the neutron scattering and xray diffraction patterns identifies the (002) peak at Q=1.3 Aa{sup 1} as predominantly magnetic. The intensity of this peak, measured from 10 to 450 K, decreases almost linearly with temperature until 350 K, becoming temperature independent above 350 K. From this, T{sub N}{approx_equal}350 K is identified to be the ordering temperature of the core spins of the nanoparticles. The width of the line is temperature independent, yielding a magnetic coherence length(approx =)particle size. The temperature variations (5300 K) of the initial susceptibility {chi} for the fieldcooled (FC) and zerofieldcooled (ZFC) cases yield a peak at T{sub p}(m){approx_equal}65 K, below which {chi}(FC)>{chi}(ZFC). For T>T{sub p}(m), the variation of {chi}{sup 1} vs T is analyzed in terms of the model of ElHilo et al., involving particlesize distribution and interparticle interactions, and substantial interparticle interactions are inferred. Following the observations in ferritin, the field dependence of the magnetization M for T>T{sub p}(m) is analyzed in terms of the modified Langevin variation: M=M{sub o}L({mu}{sub p}H/kT)+{chi}{sub a}H, where {mu}{sub p} is the magnetic moment/particle. The fit at 100 K yields {mu}{sub p}{approx_equal}250 {mu}{sub B}, consistent with the theoretical estimates based on uncompensated surface spins of Fe{sup 3+}. (c) 2000 The American Physical Society.},
doi = {10.1103/PhysRevB.61.3513},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {10980121},
number = 5,
volume = 61,
place = {United States},
year = {2000},
month = {2}
}