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Co-precipitation of iron oxide nanoparticles by rapid mixing
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics. (Engineering Material Physics-Tmfy-MSE-KTH)
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.ORCID iD: 0000-0003-2170-0076
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.ORCID iD: 0000-0003-4889-4210
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(English)Article in journal (Other academic) Submitted
Abstract [en]

Synthesis of Magnetite appears to be a topic of continued interest because of its versatility and the variety applications. Among the chemical techniques to synthesize Fe3O4, co-precipitation approach although very common, seems to be extremely sensitive to the consequences of nucleation, growth and most of all the rate of the reaction involved. This work is an attempt to demonstrate the complexities of obtaining monodispersed nanosized Fe3O4 particles. We consider the role of rapid mixing and its consequences on co-precipitation at ice-point, room temperature and boiling water temperatures on the magnetic properties of Fe3O4. We obtained crystallites varying in the range from 6.6 nm (grown in ice-water) to 7.9 nm (grown in boiling water) as determined from the broadening of XRD diffraction peaks using the Scherrer approach. With the increase of the particle size, the saturate magnetization of iron oxides increases from 52 emu/g to 63 emu/g, and the coercivity increases from 0.5 Oe to 7.9 Oe. Layers of nanosized magnetic particles on glass substrates show unusual wavelength dependence of Faraday rotation loops which show a reversal phenomenon in the sign of the magnetization around 550.

Keyword [en]
Rapid mixing co-precipitation, nanoparticles, Faraday rotation, crystallite size, magnetic property
National Category
Atom and Molecular Physics and Optics Materials Engineering
URN: urn:nbn:se:kth:diva-31405OAI: diva2:403604
QS 20120326Available from: 2011-03-14 Created: 2011-03-14 Last updated: 2012-03-26Bibliographically approved
In thesis
1. 3D Magnetic Photonic Crystals: Synthesis and Characterization
Open this publication in new window or tab >>3D Magnetic Photonic Crystals: Synthesis and Characterization
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents the synthesis methods and the characterizations of magnetic Fe3O4 nanoparticles, silica spheres with Fe3O4 nanoparticles embedded, and three dimensional magnetic photonic crystals (MPCs) prepared from the spheres. The structure, material composition, magnetic and optical properties, photonic band gaps (PBGs), as well as how these properties depend on the concentration of the magnetic nanoparticles, are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), superconducting quantum interference device (SQUID), Faraday rotation (FR) and optical spectrophotometers. Well-organized, face center cubic (fcc)-structured, super-paramagnetic 3D MPCs have been obtained and their PBGs are investigated through optical spectra.

Fe3O4 nanoparticles are synthesized by standard co-precipitation method and a rapid mixing co-precipitation method with particle size varied from 6.6 nm to 15.0 nm at different synthesis temperature (0°C ~ 100°C). The obtained Fe3O4 nanoparticles, which show crystalline structure with superparamagnetic property, are embedded into silica spheres prepared at room temperature through a sol-gel method using the hydrolysis of tetraethyl orthosilicate (TEOS) in a base solution with different concentrations. By controlling the synthesis conditions (e.g., chemicals, the ratio of chemicals and stirring time), different size of MPC spheres in range of 75 nm to 680 nm has been obtained in a narrow distribution. The sphere suspensions in ethanol are dropped on glass substrate in the permanent magnetic field to achieve well organized 3D MPCs with (111) triangular close packed crystal plane of fcc structure parallel to the surface of substrate.

From the transmission & forward scattering spectra (TF), five PBGs have been distinguished for these MPCs and they are defined as 1st, 2nd, 3rd, 4th and 5th PBGs according to the order of peaks that appear in mathematic fitting analysis. The positions (peak wavelengths) of PBGs show sphere size dependence: with the increase of the sphere size, they increase linearly. Comparing with pure SiO2 PCs at certain sphere size, the positions of PBGs for MPCs containing moderate Fe3O4 conc. (4.3 wt. %) are at longer wavelengths. On increasing the Fe3O4 conc., however, the PBGs shift back to shorter wavelength. The PBGs shift to longer or shorter wavelength is due to the combined effect of refractive index n increasing, as well as the increase of refractive index difference Δn, which are caused by the embedded Fe3O4 nanoparticles.

The transmission spectra (T) with varied incidence angle of p- and s- polarized light are studied, obtaining angular dependent and polarization sensitive PBGs. It is found that with the increase of the incidence angle, the 1st PBGs shift to shorter wavelength while the 3rd ones shift to longer wavelength. High Fe3O4 conc. MPCs (6.4 wt. %) show enhancement of this angular dependence. It is also found that the PBGs show dependence on the polarize direction of incident light. Normally, at a certain incidence angle the PBGs sift more for p- polarized incident light than for s-polarized light with respect to normal incidence. This polarized dependence can also be enhanced for high Fe3O4 conc. MPCs. With a high concentration of Fe3O4 nanoparticles, the polarization sensitivity of p- and s- increased.

These PBG properties indicate applications of 3D MPCs as functional optical materials, coatings, wavelength and polarization fibers for fiber optical communications devices and dielectric sensors of magnetic field, etc..


Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2010. 24 p.
magnetic photonic crystals, photonic band gaps, Fe3O4 nanoparticles, silica
National Category
Atom and Molecular Physics and Optics Materials Engineering
urn:nbn:se:kth:diva-11983 (URN)978-91-7415-530-3 (ISBN)
2010-02-03, Q26, KTH, Qsquldasväg 6B, Stockholm, 10:00 (English)
QC 20110224Available from: 2010-02-05 Created: 2010-02-04 Last updated: 2011-03-14Bibliographically approved

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