scholarly journals Optical Properties of Sol-Gel Nb2O5Films with Tunable Porosity for Sensing Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Rosen Georgiev ◽  
Biliana Georgieva ◽  
Marina Vasileva ◽  
Petar Ivanov ◽  
Tsvetanka Babeva
Keyword(s):  
Self Assembly ◽  
Optical Constants ◽  
Sol Gel ◽  
Reflectance Spectra ◽  
Silicon Substrates ◽  
Selected Area Electron Diffraction ◽  
Sensing Applications ◽  
Transmission Electron ◽  
Evaporation Induced Self Assembly

Thin Nb2O5films with tunable porosity are deposited by the sol-gel and evaporation induced self-assembly methods using organic template Pluronic PE6100 with different molar fractions with respect to NbCl5used as a precursor for synthesis of Nb sol. Surface morphology and structure of the films are studied by Transmission Electron Microscopy and Selected Area Electron Diffraction. The optical characterization of the films is carried out through reflectance spectra measurements of the films deposited on silicon substrates and theoretical modeling in order to obtain refractive index, extinction coefficient, and thickness of the films. The overall porosity of the films and the amount of adsorbed acetone vapors in the pores are quantified by means of Bruggeman effective medium approximation using already determined optical constants. The sensing properties of the samples are studied by measuring both the reflectance spectra and room-temperature photoluminescence spectra prior to and after exposure to acetone vapors and liquid, respectively. The potential of using the studied mesoporous Nb2O5films for chemooptical sensing is demonstrated and discussed.

Fabrication and characterization of mesoporous borosilicate glasses with different boron contents

2007 ◽  
Vol 22 (7) ◽  
pp. 1834-1838 ◽  
Author(s):  
Tongping Xiu ◽  
Qian Liu ◽  
Jiacheng Wang
Keyword(s):  
Boric Acid ◽  
Self Assembly ◽  
Sol Gel ◽  
Sorption Isotherms ◽  
Mesoporous Structure ◽  
Borosilicate Glasses ◽  
Whole Process ◽  
Transmission Electron ◽  
Evaporation Induced Self Assembly ◽  
The Stability

A series of wormhole-like mesoporous borosilicate glasses (MBSGs) with different compositions has been prepared by a combination of surfactant templating, sol-gel methods, and evaporation-induced self-assembly processes. Small-angle x-ray diffraction, high-resolution transmission electron microscopy, and N2 sorption isotherms analysis showed that all the MBSGs prepared possess the mesoporous structure. However, the stability of the mesoporous structure is strongly affected by the boron contents. When boron content was increased, boric acid was found in the final product, and the mesoporous structure was partially degraded. The formation and loss of boric acid through the whole process may account for the partial collapse of the mesostructure.

Synthesis and Characterization of Mesoporous Silica Nanoparticles Embedded Gadolinium Oxide

2011 ◽  
Vol 306-307 ◽  
pp. 1275-1279 ◽  
Author(s):  
Ning Qi Luo ◽  
Zhan Yun Huang ◽  
Ping Luo ◽  
Yuan Zhi Shao ◽  
Di Hu Chen
Keyword(s):  
Mesoporous Silica ◽  
Self Assembly ◽  
Mesoporous Silica Nanoparticles ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Gadolinium Oxide ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
The Mean

We first synthesized gadolinium oxide (Gd2O3) by a modified “polyol” strategy and then embedded it into mesoporous silica by a simple self-assembly sol-gel reaction. Scanning electron microscope (SEM) results show that the samples have good sphericity and good dispersibility. The structure of mesoporous silica was characterized by transmission electron microscopy (TEM) and small-angle X-ray diffraction (SAXRD). Results show that the mesoporous structure has not been destroyed after gadolinium oxide imbedding. The ratio of gadolinium and silica was determined by the mean of energy dispersive spectroscopy (EDS).

Synthesis and characterization of ZnO-TiO2/CoFe2O4 hollow photocatalyst: Magnetic recovery and highly efficient photocatalytic performance

2020 ◽  
Vol 13 (06) ◽  
pp. 2051027
Author(s):  
Hong-Xia Jing ◽  
Long-Xiang Li ◽  
Jing Huang ◽  
Na Li ◽  
Wang-Jun Pei ◽  
...  
Keyword(s):  
Self Assembly ◽  
Photocatalytic Performance ◽  
Sol Gel ◽  
Vibrating Sample Magnetometer ◽  
X Ray ◽  
Transmission Electron ◽  
Magnetic Recovery ◽  
Fluorescence Spectrometer ◽  
Semiconductor Photocatalyst

TiO2 has been known as an excellent semiconductor photocatalyst for wastewater treatment purposes. But, its visible light efficiency is low and cannot be easily recovered from the reaction mixture. In order to overcome these major disadvantages, a novel hollow magnetically recoverable ZnO-TiO2/CoFe2O4 photocatalyst is synthesized by the sol–gel and layer self-assembly methods. The synthesized photocatalyst was characterized by means of X-ray diffractometer (XRD), Transmission electron microscopy (TEM), Vibrating sample magnetometer (VSM), Fluorescence spectrometer (FL), and UV-Vis/DRS techniques. Complete degradation of rhodamine B is attained in the presence of ZnO-TiO2/CoFe2O4 photocatalyst under the irradiation of ultraviolet and sunlight within 90[Formula: see text]min. The photocatalyst can be repeatedly reused for five times without significantly diminishing of its photocatalytic performance.

Synthesis, characterization, and photocatalytic properties of pyrochlore Bi2Ti2O7 nanotubes

2006 ◽  
Vol 21 (11) ◽  
pp. 2941-2947 ◽  
Author(s):  
Hongjun Zhou ◽  
Tae-Jin Park ◽  
Stanislaus S. Wong
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Bulk Sample ◽  
X Ray Diffraction ◽  
Alumina Template ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
High Resolution Tem

Bismuth titanate (Bi2Ti2O7) nanotubes were successfully synthesized with an alumina template-based sol-gel technique. As-synthesized nanotubes are smooth and uniform with diameters ranging from 180 to 330 nm and lengths varying from 7 to 12 μm. Extensive characterization of as-prepared samples has been performed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), energy-dispersive x-ray spectroscopy (EDS), and selected-area electron diffraction (SAED). Photocatalytic studies indicate that as-prepared nanotubes possess higher photocatalytic activity than the corresponding bulk sample prepared without the use of an alumina template.

Fabrication of Organized Mesoporous TiO2 Films Assembled via Different Template and Characterization of their Photocatalytic Activity

2013 ◽  
Vol 669 ◽  
pp. 95-98
Author(s):  
Dan Li ◽  
Bin Du ◽  
Zhi Heng Zhao ◽  
Wen Heng Jing ◽  
Wei Hong Xing
Keyword(s):  
Photocatalytic Activity ◽  
Self Assembly ◽  
Sol Gel ◽  
Methyl Orange Solution ◽  
Mesoporous Films ◽  
Guest Molecules ◽  
Evaporation Induced Self Assembly ◽  
Diffusion Paths ◽  
Cubic Mesoporous

Hexagonal and cubic mesoporous TiO2 materials were synthesized via a sol-gel route modified by evaporation–induced self–assembly process with different templates. XRD and TEM results confirmed that the mesoporous films were highly organized. Furthermore, the hexagonal mesoporous TiO2 films were formed in the P123-templated films, whereas the cubic structure ones were found in the F127-templated films. Both the hexagonal and cubic mesoporous films showed photocatalytic activity in decomposing methyl orange solution under UV region, among which the cubic mesostructure presented superior potocatalytic activity because of larger surface area, more open framework and less obstructed diffusion paths of guest molecules.

TEM characterization of Au/Polysilicon interactions

1990 ◽  
Vol 48 (4) ◽  
pp. 650-651
Author(s):  
N. David Theodore ◽  
Leslie H. Allen ◽  
C. Barry Carter ◽  
James W. Mayer
Keyword(s):  
Solid Phase ◽  
Single Crystal Silicon ◽  
Chemical Vapor ◽  
Electrical Contacts ◽  
Silicon Substrates ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Polysilicon Films ◽  
The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

Characterization of ordered mesoporous films on silicon (001) surface using X-ray and electron diffraction

2005 ◽  
Vol 38 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Pang-Hung Liu ◽  
Kuei-Jung Chao ◽  
Xing-Jian Guo ◽  
Kuo-Ying Huang ◽  
Yen-Ru Lee ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Sol Gel ◽  
Dip Coating ◽  
Silica Film ◽  
Continuous Film ◽  
X Ray ◽  
Transmission Electron ◽  
Ordered Mesoporous ◽  
Direction Dependence

A continuous silica film with well aligned mesochannels parallel to the Si(001) surface was found to be formed through sol–gel dip-coating of a silica precursor with nonionic ethylene oxide surfactant. Two two-dimensional mesoporous structures in centered and non-centered rectangular symmetries and with the short axes of elongated ellipsoidal pores normal to the surface were observed by X-ray and electron diffraction. Detailed transmission electron microscopy investigations were employed to view the direction dependence of the channel or pore packing in the continuous film.

CONTROLLED SYNTHESIS AND CHARACTERIZATION OF TiO2 NANOPARTICLES VIA A SOL–GEL METHOD

2004 ◽  
Vol 03 (06) ◽  
pp. 749-755 ◽  
Author(s):  
YING LI ◽  
SUO HON LIM ◽  
TIM WHITE
Keyword(s):  
Sol Gel ◽  
Critical Role ◽  
Rietveld Analysis ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Gelation Temperature ◽  
Gel Method ◽  
Sol Gel Method ◽  
Transmission Electron

The properties influencing the photocatalytic activity of TiO 2 particles have been suggested to include the surface area, crystallinity, crystallite size and crystal structure. Therefore, manipulation of the microstructure of titania, especially of nanocrystalline powders, is very important in the preparative process. In this study, nanocrystalline TiO 2 powders with controlled particle size and phase composition were synthesized at low temperature (<80°C) by a modified sol–gel method. The effects of gelation temperature were systematically investigated. It was found that this parameter played a critical role in determining the crystallinity of single phase anatase. With increasing gelation temperature, the crystallinity of anatase improved initially and then decreased if the temperature was raised to 80°C. These nanomaterials were characterized comprehensively by powder X-ray diffraction (including Rietveld analysis), high-resolution transmission electron microscopy, DSC/TGA thermal analysis and UV–Vis spectrometry.

scholarly journals Effect of boron incorporation on the bioactivity, structure, and mechanical properties of ordered mesoporous bioactive glasses

2020 ◽  
Vol 8 (7) ◽  
pp. 1456-1465 ◽  
Author(s):  
Leonie Deilmann ◽  
Oliver Winter ◽  
Bianca Cerrutti ◽  
Henrik Bradtmüller ◽  
Christopher Herzig ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Sol Gel ◽  
Bioactive Glasses ◽  
Structure Directing Agent ◽  
Structural Investigations ◽  
Ordered Mesoporous ◽  
Evaporation Induced Self Assembly

B2O3 doped (0.5–15 mol%) ordered mesoporous bioactive glasses were synthesized via sol–gel based evaporation-induced self-assembly using P123 as a structure directing agent and characterized by biokinetic, mechanical and structural investigations.

SYNTHESIS AND OPTICAL CHARACTERIZATION OF PYROELECTRIC NANOPOWDERS BASED ON PZT (95/5)

2010 ◽  
Vol 09 (03) ◽  
pp. 193-199 ◽  
Author(s):  
E. PAKIZEH ◽  
S. M. HOSSEINI ◽  
A. KOMPANY ◽  
M. GHASEMIFARD
Keyword(s):  
Low Temperatures ◽  
Optical Constants ◽  
Sol Gel ◽  
Normal Incidence ◽  
Optical Characterization ◽  
Analysis Program ◽  
Secondary Phases ◽  
Ir Reflectance ◽  
Gel Technique

Pb(Zr1-x, Tix)O3 (x = 0.05) with pyroelectric properties have been synthesized by sol–gel technique at low temperatures. XRD results indicate that the powder has perovskite structure without secondary phases and the average of particle size was estimated to be about 40 nm in diameters. The optical constants such as refractive index, n, extinction coefficient, k, and the dielectric function of PZT nanopowders have been investigated by Fourier transmittance infrared (FTIR) spectrum and Kramers–Kronig (KK) analysis program. The use of the KK method to analyze the normal incidence infrared (IR) reflectance spectra with a single resonance has also been described. The results indicated that the optical constant increases slowly as temperature of calcinations increases.

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