scholarly journals Poly(styrene/α-tertbutoxy-ω-vinylbenzyl-polyglycidol) micro spheres for the preparation of novel photonic crystals

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Teresa Basinska ◽  
Loïg Kergoat ◽  
Claire Mangeney ◽  
Mohamed M. Chehimi ◽  
Stanislaw Slomkowski
Keyword(s):  
Photonic Crystal ◽  
Colloidal Crystal ◽  
Stop Band ◽  
Particle Surface ◽  
Visible Region ◽  
Diffraction Peak ◽  
Bragg Diffraction ◽  
Surface Chemical ◽  
Surface Chemical Composition ◽  
Bragg Diffraction Peak

AbstractWe report on the preparation of a novel photonic crystal assembled from poly(styrene/α-tertbutoxy-ω-vinylbenzyl-polyglycidol) microspheres. The latex particles were fully characterized in terms of size (271 nm, Dw/Dn=1.004), electrophoretic mobility (-3.79x10-8 m2V-1s-1) and surface chemical composition (evidence for a PGL-rich particle surface). They were then assembled into 3D colloidal crystal showing an optical stop band in the visible region. The λmax for the Bragg diffraction peak is 570 nm. As the particles under study are highly hydrophilic and biocompatible, this work opens up new opportunities for the design of photonic crystal-based biosensing devices.

scholarly journals Preparation of inverse opal zirconia

2018 ◽  
Vol 50 (3) ◽  
pp. 387-394
Author(s):  
Xiao-Peng Li ◽  
Li-Li Wang ◽  
Zai-Lei Gong ◽  
Xiu-Feng Wang ◽  
Ye-Ming Zhou
Keyword(s):  
Colloidal Crystal ◽  
Stop Band ◽  
Visible Region ◽  
Holding Time ◽  
Inverse Opal ◽  
Mass Ratio ◽  
Templating Method ◽  
Assembly Method ◽  
Precursor Ratio ◽  
Colloidal Crystal Templating

Inverse opal zirconia is useful in many ways because of their ability to combine several chemical and physical properties. In this research, polystyrene template was fabricated by self-assembly method and inverse opal zirconia was prepared by colloidal crystal-templating method. The process of preparation of inverse opal zirconia as well as effects on morphology and phase of as-prepared inverse opal zirconia were studied. The results showed precursor ratio of zirconium acetate and methanol, mass ratio of polystyrene templates and precursor and dipping times had remarkable influence on morphology of inverse opal zirconia. When the precursor ratio was 1:1; the mass ratio was 1:15 and dipped once, much better morphology of inverse opal zirconia was obtained. The mass ratio, sintering temperature and holding time had significant effect on crystallization of zirconia. Pure phase zirconia could be obtained when sintered at 600 oC, holding time was 2h and the mass ratio was 1:1. A distinguished single stop band in the visible region of the spectrum and unique structural color were observed in inverse opal zirconia, which will make this material promising candidate for novel pigment.

scholarly journals Limitations of asymmetric parallel-beam geometry

2004 ◽  
Vol 37 (3) ◽  
pp. 357-361 ◽  
Author(s):  
N. A. Raftery ◽  
R. Vogel
Keyword(s):  
Rietveld Analysis ◽  
Lanthanum Hexaboride ◽  
Diffraction Peak ◽  
Bragg Diffraction ◽  
Parallel Beam ◽  
Beam Geometry ◽  
Quantitative Studies ◽  
Parallel Beam Geometry ◽  
Nist Standard Reference Material ◽  
Bragg Diffraction Peak

Bragg diffraction peak profiles and intensities in asymmetric (Ω–2θ) diffraction using a mirror-based parallel-beam geometry were compared with symmetric parallel-beam (θ–2θ) and conventional Bragg–Brentano (θ–2θ) diffraction for a powdered quartz sample and the NIST standard reference material (SRM) 660a (LaB6, lanthanum hexaboride). A comparison of the intensities and line widths (full width at half-maximum, FWHM) of these techniques demonstrated that low incident angles (Ω < 5°) are preferable for the parallel-beam setup. For higher Ω values, if 2θ < 2Ω, mass absorption reduces the intensities significantly compared with the Bragg–Brentano setup. The diffraction peak shapes for the mirror geometry are more asymmetric and have larger FWHM values than corresponding peaks recorded with a Bragg–Brentano geometry. An asymmetric mirror-based parallel-beam geometry offers some advantages in respect of intensity when compared with symmetric geometries, and hence may be well suited to quantitative studies, such as those involving Rietveld analysis. A trial Rietveld refinement of a 50% quartz–50% corundum mixture was performed and produced adequate results.

scholarly journals Spectra of M Dwarfs - Dimmed by Dust

1998 ◽  
Vol 11 (1) ◽  
pp. 439-440
Author(s):  
T. Tsuji ◽  
K. Ohnaka ◽  
W. Aoki ◽  
H.R.A. Jones
Keyword(s):  
Chemical Composition ◽  
Brown Dwarfs ◽  
Surface Chemical ◽  
Basic Information ◽  
M Dwarfs ◽  
Surface Chemical Composition ◽  
Molecular Lines ◽  
Low Mass

Spectra of M dwarfs are rich in atomic and molecular lines. These spectra provide such basic information as Teff (or radius), log g (or mass), surface chemical composition, and something more (e.g. activity) if properly interpreted. It is recognized, however, that spectra of M dwarfs are already dimmed by the dust formed in their photospheres (Tsuji et al. 1996a) and this effect, which has been overlooked until recently, should be taken into account in any interpretation and analysis of the spectra of very low mass objects (VLMOs) including late M dwarfs and brown dwarfs.

scholarly journals Surface Texture of Microcrystalline Tunnel-Structured Manganese(IV) Oxides: Nitrogen Sorptiometry and Electron Microscopy Studies

2002 ◽  
Vol 20 (7) ◽  
pp. 619-632 ◽  
Author(s):  
A.A. Ali ◽  
F.A. Al-Sagheer ◽  
M.I. Zaki
Keyword(s):  
Electron Microscopy ◽  
Chemical Composition ◽  
Surface Texture ◽  
Particle Morphology ◽  
High Resolution Electron Microscopy ◽  
Surface Chemical ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Surface Chemical Composition ◽  
Resolution Electron

Three different modifications of manganese(IV) oxide, viz. cryptomelane, nsutite and todorokite-like, were synthesized by hydrothermal methods. The bulk chemical composition, phase composition, crystalline structure and particle morphology of the resulting materials were determined by thermogravimetry, atomic absorption spectroscopy, X-ray diffractometry, infrared spectroscopy and scanning electron microscopy. The surface chemical composition, texture and structure were assessed using X-ray photoelectron microscopy, nitrogen sorptiometry and high-resolution electron microscopy. The results highlighted the hydrothermal conditions under which such tunnel-structured modifications of manganese(IV) oxide can be successfully synthesized. Moreover, they revealed that (i) the bulk was microcrystalline, (ii) the crystallites were either fibrils (cryptomelane and nsutite) or rod-like (todorokite) with low-index exposed facets, (iii) the surface chemical composition mostly reflected that of the bulk and (iv) the surface texture was linked with high specific areas, slit-shaped mesopores associated with particle interstices and micropores which allowed surface accessibility to the bulk tunnels of the test oxides. The application of such test oxides as shape-selective oxidation catalysts appears worthy of investigation.

scholarly journals Abrasion Resistance of Superhydrophobic Coatings on Aluminum Using PDMS/SiO2

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 414 ◽  
Author(s):  
Divine Sebastian ◽  
Chun-Wei Yao ◽  
Ian Lian
Keyword(s):  
Silica Nanoparticles ◽  
Abrasion Resistance ◽  
Functionalized Silica ◽  
Surface Chemical ◽  
X Ray ◽  
Force Microscopy ◽  
Surface Chemical Composition ◽  
Superhydrophobic Coatings ◽  
Atomic Force ◽  
High Contact Angle

Superhydrophobic coatings have shown tremendous improvement in the usability of metals such as aluminum. These coatings are capable of adding attractive features such as self-cleaning, anti-corrosion, and anti-biofouling to the array of diverse features that aluminum possesses, including lightweight and high ductility. For superhydrophobic surfaces, having considerable abrasion resistance is as important as achieving a high contact angle. In this work, two types of coatings have been prepared, each composed of functionalized silica nanoparticles along with polydimethylsiloxane (PDMS) dispersed in ethanol, and their superhydrophobicity and abrasion characteristics have been investigated. The same silica nanoparticles are present in each coating, but each has a different proportion of the PDMS base to its curing agent. The surface morphology of the coatings was studied with the aid of a scanning electron microscope (SEM) and an atomic force microscope (AFM). The surface chemical composition was characterized using an energy dispersive X-ray spectroscope (EDX). The prepared coatings were analyzed for their degree of superhydrophobicity, abrasion resistance and adhesion characteristics. In addition, atomic force microscopy was used to understand the adhesion characteristics of the coatings.

scholarly journals Position Dependence of Emission Wavelength of a SiO2 Colloidal Photonic-Crystal Laser

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 802 ◽  
Author(s):  
Ting-Hui Chen ◽  
Bing-Yau Huang ◽  
Chie-Tong Kuo
Keyword(s):  
Photonic Crystal ◽  
Colloidal Crystal ◽  
Threshold Energy ◽  
Silica Particles ◽  
Wavelength Tunable ◽  
Coffee Ring ◽  
Crystal Laser ◽  
Coffee Ring Effect ◽  
Photonic Crystal Laser ◽  
Ring Effect

In this paper, a wavelength tunable colloidal-crystal laser with monodispersed silica particles was demonstrated. Silica particles were synthesized through the modified Stöber process and self-assembled into the colloidal photonic-crystal structure, which was then used to form the optic cavity of a wavelength tunable laser device. Due to Bragg’s diffraction of the colloidal photonic-crystal and the coffee ring effect, the forbidden energy gap of light varied with different lattice sizes at different positions of the colloidal photonic-crystal. When the pumping pulsed laser irradiated on the gain medium of the sample, the fluorescence was restricted and enhanced by the colloidal photonic-crystal. Lasing emission with a single peak occurred when the energy of the pumping laser exceeded the threshold energy. The threshold energy and the full-width at half-maximum (FWHM) of the proposed laser were 7.63 µJ/pulse and 2.88 nm, respectively. Moreover, the lasing wavelength of the colloidal photonic-crystal laser could be tuned from 604 nm to 594 nm, corresponding to the various positions in the sample due to the coffee ring effect.

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