Synthesis of γ-Fe 2 O 3 nanoparticles coated on silica spheres: Structural and magnetic properties

S. Chakrabarti, S. K. Mandal, B. K. Nath, D. Das, D. Ganguli, S. Chaudhuri

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The structural and magnetic properties of γ-Fe 2 O 3 nanoparticles dispersed on silica spheres prepared by sol-gel method were investigated. The properties of γ-Fe 2 O 3 nanoparticles without silica were compared with those on silica spheres. Both the nanoparticle assemblages were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Mössbauer (20, 80 and 300 K) and electron paramagnetic resonance (EPR) (80, 300 K) measurements. The XRD spectra clearly indicated the formation of pure γ-Fe 2 O 3 nanoparticles and the absence of any other form of iron oxide. TEM images showed a uniform distribution of the nanoparticles of size ∼6 nm on the surfaces of silica spheres (diameter ∼35-60 nm). The size of the individual nanoparticles (without silica) varied within 5-6 nm. The low temperature (20 K) Mössbauer spectra consisted of a partially split sextet superimposed on a doublet. The partial magnetic splitting of the sextet at 20 K revealed the effect of surface magnetization and surface modifications of the γ-Fe 2 O 3 nanoparticles coated on silica spheres. The gradual collapse of the partially split sextet into a doublet with increasing temperature indicated the superparamagnetic relaxation exhibited by the γ-Fe 2 O 3 nanoparticles with/without silica. The surface magnetization arising out of mis-aligned spins at the surface as evidenced by Mössbauer spectra was further confirmed by electron paramagnetic resonance (EPR) studies.

LanguageEnglish
Pages163-171
Number of pages9
JournalEuropean Physical Journal B
Volume34
Issue number2
DOIs
Publication statusPublished - 1 Jul 2003

Fingerprint

Silicon Dioxide
Structural properties
Magnetic properties
Silica
Nanoparticles
silicon dioxide
magnetic properties
nanoparticles
synthesis
Paramagnetic resonance
Magnetization
electron paramagnetic resonance
Electron microscopes
electron microscopes
X ray diffraction
magnetization
Iron oxides
diffraction
iron oxides
Sol-gel process

Cite this

Chakrabarti, S. ; Mandal, S. K. ; Nath, B. K. ; Das, D. ; Ganguli, D. ; Chaudhuri, S. / Synthesis of γ-Fe 2 O 3 nanoparticles coated on silica spheres : Structural and magnetic properties. In: European Physical Journal B. 2003 ; Vol. 34, No. 2. pp. 163-171.
@article{cdedf857d10a4034ab407e1af2a79a80,
title = "Synthesis of γ-Fe 2 O 3 nanoparticles coated on silica spheres: Structural and magnetic properties",
abstract = "The structural and magnetic properties of γ-Fe 2 O 3 nanoparticles dispersed on silica spheres prepared by sol-gel method were investigated. The properties of γ-Fe 2 O 3 nanoparticles without silica were compared with those on silica spheres. Both the nanoparticle assemblages were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), M{\"o}ssbauer (20, 80 and 300 K) and electron paramagnetic resonance (EPR) (80, 300 K) measurements. The XRD spectra clearly indicated the formation of pure γ-Fe 2 O 3 nanoparticles and the absence of any other form of iron oxide. TEM images showed a uniform distribution of the nanoparticles of size ∼6 nm on the surfaces of silica spheres (diameter ∼35-60 nm). The size of the individual nanoparticles (without silica) varied within 5-6 nm. The low temperature (20 K) M{\"o}ssbauer spectra consisted of a partially split sextet superimposed on a doublet. The partial magnetic splitting of the sextet at 20 K revealed the effect of surface magnetization and surface modifications of the γ-Fe 2 O 3 nanoparticles coated on silica spheres. The gradual collapse of the partially split sextet into a doublet with increasing temperature indicated the superparamagnetic relaxation exhibited by the γ-Fe 2 O 3 nanoparticles with/without silica. The surface magnetization arising out of mis-aligned spins at the surface as evidenced by M{\"o}ssbauer spectra was further confirmed by electron paramagnetic resonance (EPR) studies.",
author = "S. Chakrabarti and Mandal, {S. K.} and Nath, {B. K.} and D. Das and D. Ganguli and S. Chaudhuri",
year = "2003",
month = "7",
day = "1",
doi = "10.1140/epjb/e2003-00208-2",
language = "English",
volume = "34",
pages = "163--171",
journal = "European Physical Journal B: Condensed Matter and Complex Systems",
issn = "1434-6028",
number = "2",

}

Synthesis of γ-Fe 2 O 3 nanoparticles coated on silica spheres : Structural and magnetic properties. / Chakrabarti, S.; Mandal, S. K.; Nath, B. K.; Das, D.; Ganguli, D.; Chaudhuri, S.

In: European Physical Journal B, Vol. 34, No. 2, 01.07.2003, p. 163-171.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis of γ-Fe 2 O 3 nanoparticles coated on silica spheres

T2 - European Physical Journal B: Condensed Matter and Complex Systems

AU - Chakrabarti, S.

AU - Mandal, S. K.

AU - Nath, B. K.

AU - Das, D.

AU - Ganguli, D.

AU - Chaudhuri, S.

PY - 2003/7/1

Y1 - 2003/7/1

N2 - The structural and magnetic properties of γ-Fe 2 O 3 nanoparticles dispersed on silica spheres prepared by sol-gel method were investigated. The properties of γ-Fe 2 O 3 nanoparticles without silica were compared with those on silica spheres. Both the nanoparticle assemblages were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Mössbauer (20, 80 and 300 K) and electron paramagnetic resonance (EPR) (80, 300 K) measurements. The XRD spectra clearly indicated the formation of pure γ-Fe 2 O 3 nanoparticles and the absence of any other form of iron oxide. TEM images showed a uniform distribution of the nanoparticles of size ∼6 nm on the surfaces of silica spheres (diameter ∼35-60 nm). The size of the individual nanoparticles (without silica) varied within 5-6 nm. The low temperature (20 K) Mössbauer spectra consisted of a partially split sextet superimposed on a doublet. The partial magnetic splitting of the sextet at 20 K revealed the effect of surface magnetization and surface modifications of the γ-Fe 2 O 3 nanoparticles coated on silica spheres. The gradual collapse of the partially split sextet into a doublet with increasing temperature indicated the superparamagnetic relaxation exhibited by the γ-Fe 2 O 3 nanoparticles with/without silica. The surface magnetization arising out of mis-aligned spins at the surface as evidenced by Mössbauer spectra was further confirmed by electron paramagnetic resonance (EPR) studies.

AB - The structural and magnetic properties of γ-Fe 2 O 3 nanoparticles dispersed on silica spheres prepared by sol-gel method were investigated. The properties of γ-Fe 2 O 3 nanoparticles without silica were compared with those on silica spheres. Both the nanoparticle assemblages were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Mössbauer (20, 80 and 300 K) and electron paramagnetic resonance (EPR) (80, 300 K) measurements. The XRD spectra clearly indicated the formation of pure γ-Fe 2 O 3 nanoparticles and the absence of any other form of iron oxide. TEM images showed a uniform distribution of the nanoparticles of size ∼6 nm on the surfaces of silica spheres (diameter ∼35-60 nm). The size of the individual nanoparticles (without silica) varied within 5-6 nm. The low temperature (20 K) Mössbauer spectra consisted of a partially split sextet superimposed on a doublet. The partial magnetic splitting of the sextet at 20 K revealed the effect of surface magnetization and surface modifications of the γ-Fe 2 O 3 nanoparticles coated on silica spheres. The gradual collapse of the partially split sextet into a doublet with increasing temperature indicated the superparamagnetic relaxation exhibited by the γ-Fe 2 O 3 nanoparticles with/without silica. The surface magnetization arising out of mis-aligned spins at the surface as evidenced by Mössbauer spectra was further confirmed by electron paramagnetic resonance (EPR) studies.

UR - http://www.scopus.com/inward/record.url?scp=4544296678&partnerID=8YFLogxK

U2 - 10.1140/epjb/e2003-00208-2

DO - 10.1140/epjb/e2003-00208-2

M3 - Article

VL - 34

SP - 163

EP - 171

JO - European Physical Journal B: Condensed Matter and Complex Systems

JF - European Physical Journal B: Condensed Matter and Complex Systems

SN - 1434-6028

IS - 2

ER -