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3D Magnetic Photonic Crystals: Synthesis and Characterization
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics. (Engineering Material Physics-Tmfy-MSE-KTH)
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.
Keyword [en]
magnetic photonic crystals, photonic band gaps, Fe3O4 nanoparticles, silica
National Category
Atom and Molecular Physics and Optics Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-11983ISBN: 978-91-7415-530-3 (print)OAI: oai:DiVA.org:kth-11983DiVA: diva2:292176
Presentation
2010-02-03, Q26, KTH, Qsquldasväg 6B, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20110224Available from: 2010-02-05 Created: 2010-02-04 Last updated: 2011-03-14Bibliographically approved
List of papers
1. Enhanced linear sphere size dependence of photonic band gaps for 3D nanocomposite magnetic photonic crystals
Open this publication in new window or tab >>Enhanced linear sphere size dependence of photonic band gaps for 3D nanocomposite magnetic photonic crystals
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2010 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550Article in journal (Other academic) Submitted
Abstract [en]

Silica spheres in the size range (70-650) nm, containing embedded nano-sized magnetic iron oxide particles have been synthesized and arranged into 3D-face-centered-cubic (fcc) structured magnetic photonic crystals (MPCs) with the (111) crystal plane parallel to the glass substrate surface. Five photonic band gaps (PBGs) are observed in the optical transmission spectra measured over UV-Vis-near IR range for MPCs. The peak wavelengths of the PBGs (λC) are found to increase linearly with the sphere size (Φ). Furthermore, on embedding magnetic nanoparticles the position of PBGs is shifted to higher wavelengths. In addition, the average refractive index, 1.5 ± 0.1, obtained for the MPCs from the slopes of λC(Φ) is found to be larger than the reported value of 1.349 for pure silica PCs.

National Category
Atom and Molecular Physics and Optics Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31402 (URN)
Note
QS 20120315Available from: 2011-03-14 Created: 2011-03-14 Last updated: 2017-12-11Bibliographically approved
2. Effect of Fe3O4 nanoparticles on the optical transmission properties of 3D magnetic photonic crystals
Open this publication in new window or tab >>Effect of Fe3O4 nanoparticles on the optical transmission properties of 3D magnetic photonic crystals
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2010 (English)In: Physics ReviewArticle in journal (Other academic) Submitted
Abstract [en]

Magnetic and optical properties of three-dimensional magnetic photonic crystals (MPCs), consisting of silica spheres in the size range 190-680nm embedded with 8, 9 and 13 nm Fe3O4 nanoparticles, have been investigated. All the PC-films, with and without embedded magnetic nanoparticles, show five band gaps at well defined wavelengths in their optical transmission spectrum. The band gaps are found to be a linear function of the constituent sphere size in the MPC films. From the slope of this function, the deduced refractive index for the constituents in the films is found to increase with the concentration of the embedded magnetite nanoparticles. The observed shifts in the photonic band gaps PBGs in the films is qualitatively explained in terms of the variations of refractive index and the contrast index difference arising from the concentration of the embedded nanoparticles. We also find that the angular dependence of PBG positions for MPCs at small incidence angles is strongly dependent on the p- and s- polarization states of the incident light. The polarization sensitivity of PBGs to the Fe3O4 concentration is also discussed.  

National Category
Atom and Molecular Physics and Optics Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31403 (URN)
Note
QS 20120315Available from: 2011-03-14 Created: 2011-03-14 Last updated: 2012-03-15Bibliographically approved
3. Co-precipitation of iron oxide nanoparticles by rapid mixing
Open this publication in new window or tab >>Co-precipitation of iron oxide nanoparticles by rapid mixing
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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
Rapid mixing co-precipitation, nanoparticles, Faraday rotation, crystallite size, magnetic property
National Category
Atom and Molecular Physics and Optics Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31405 (URN)
Note
QS 20120326Available from: 2011-03-14 Created: 2011-03-14 Last updated: 2012-03-26Bibliographically approved
4. Mathematical analysis of the transmission spectrum and photonic band gaps for a low-refractive-index magnetic photonic crystal
Open this publication in new window or tab >>Mathematical analysis of the transmission spectrum and photonic band gaps for a low-refractive-index magnetic photonic crystal
2011 (English)Article in journal (Other academic) Submitted
National Category
Atom and Molecular Physics and Optics Materials Engineering
Identifiers
urn:nbn:se:kth:diva-31406 (URN)
Note
QS 20120319Available from: 2011-03-14 Created: 2011-03-14 Last updated: 2012-03-19Bibliographically approved

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