Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1717-1729
Author(s):  
Kalaichelvi Saravanamuttu ◽  
Xin Min Du ◽  
S Iraj Najafi ◽  
Mark P Andrews
Keyword(s):  
Refractive Index ◽  
Sol Gel ◽  
Organic Component ◽  
Wave Guide ◽  
Nanocomposite Films ◽  
Wave Number ◽  
Bragg Grating ◽  
Ir Absorption ◽  
Absorption Bands ◽  
High Reflectivity

The solution sol-gel method is used to produce thin films of photosensitive hybrid organic-inorganic glass on silicon. Glasses consisted of photoinitiator, methacryloxypropyltrimethoxysilane, methacrylic acid, and zirconium oxide. Clear, low optical loss films are obtained, indicating nanophase homogeneity in the samples. The nanocomposite films are shown to be suitable for fabricating optical components such as ridge wave guides and Bragg diffraction gratings. The increase in the refractive index of the glass relative to the surrounding material during photolithographic processing is identified as a key material parameter in device fabrication. Accordingly, electronic and vibrational spectroscopy are used to provide insight into the structural changes that occur when glasses are irradiated with continuous narrow band 4.9 eV and pulsed 6.4 eV light. Arguments are advanced, linking the changes in refractive index to collateral densification leading to volume compaction of the silicate network during organic free-radical polymerization. This was shown by following the time evolution of relevant IR absorption bands. Free silanol and unreacted methoxysilane are consumed in the process. Matrix densification is indicated by shifts to low wave number in the transverse optical phonon mode associated with decreasing Si-O-Si bond angles of the antisymmetric stretching vibration (compression). Growth in the Si-O-Si framework is observed through increased intensity in this IR absorption. Similar behaviour is observed for films irradiated with 6.4 eV light from an excimer laser. A phase mask in combination with pulsed 6.4 eV light is used to inscribe a 1.5 mm, high-reflectivity polarization-independent Bragg grating into a ridge wave guide. The high reflectivity is thought to arise from a periodic modulation of the volume compaction of the matrix. Overall, the organic component of the glass confers unique properties on the material that allow it to be densified even with 4.9 eV light. By comparison, sol-gel silica with no organic component must be densified at nearly twice the photon energy.Key words: sol-gel, wave guide, Bragg grating, photochemistry, densification, refractive index, photolithography.

Modification of Sol-Gel Thin Films By Ion Implantation

1994 ◽  
Vol 346 ◽  
Author(s):  
Hiroshi Hirashima ◽  
Kenji Adachi ◽  
Hiroaki Imai
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Ion Implantation ◽  
Sol Gel ◽  
The Other ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Chemically Modified ◽  
Sol Gel Films ◽  
Ion Species

ABSTRACTIn order to densify and to improve the physical properties, TiO2 sol-gel films, about 100 nm in thickness, on silica glass or silicon wafer were implanted with Ar+ or B+ ions. The refractive index of the as-dried films increased and the IR absorption band of OH disappeared after Ar+ implantation. Drying and densification of sol-gel films were enhanced by Ar+ implantation. On the other hand, the refractive index and the thickness of the films hardly changed with B+ implantation. However, IR absorption bands of B-O bond were observed after B+ implantation. This suggests that sol-gel films could be chemically modified by ion implantation with reactive ion species.

scholarly journals Rietveld Structure Refinement and Cation Distribution of Substituted Nanocrystalline Ni-Zn Ferrites

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
A. A. Birajdar ◽  
Sagar E. Shirsath ◽  
R. H. Kadam ◽  
S. M. Patange ◽  
D. R. Mane ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Structure Refinement ◽  
Sol Gel ◽  
Unit Cell Dimension ◽  
Unit Cell ◽  
Wave Number ◽  
Absorption Bands ◽  
Number Range ◽  
Wave Number Range ◽  
Unit Cell Dimensions

Ferrite nanoparticles of were prepared by a sol-gel autocombustion method. The prepared samples were shown to have a cubic spinel structure by applying the full pattern fitting of the Rietveld method. The unit cell dimension, discrepancy factor, and interatomic distance have been determined. As the Cr3+ content x increases, the unit cell dimensions and crystallite size are decreased. The IR spectra show two absorption bands in the wave number range of 400 to 600 cm−1.

scholarly journals Optical properties of alumina films by sol gel acrylamide route

2021 ◽  
Vol 23 (10) ◽  
pp. 38-43
Author(s):  
G. Ramanathan ◽  
◽  
K.R. Murali ◽  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Gelling Agent ◽  
Absorption Bands ◽  
Ammonium Persulphate ◽  
Alumina Films ◽  
Different Temperatures

A new acrylamide route was applied to prepare alumina films by using aluminum chloride as a starting material and ammonium persulphate solution as the gelling agent. The XRD results show that the films are amorphous for the post anneals temperatures up to 300 °C, beyond this temperature; peaks corresponding to γ-Al2O3 are observed. XPS studies indicated the peaks corresponding to the Al 2p spectra of films after annealing at different temperatures. The FTIR spectra reveal absorption bands of Al-O and to lattice. The absorption co-efficient was 1014 cm- 1.Refractive index was in the range of 1.71 to 1.61 with increase of wavelength from 250-500 nm. Optical band gap value was around 5.40-5.75 eV with increase of annealing temperature.

Nevirapine Pharmaceutical Cocrystal: Design, Development and Formulation

2019 ◽  
Vol 9 (3) ◽  
pp. 240-247
Author(s):  
Prabhakar Panzade ◽  
Priyanka Somani ◽  
Pavan Rathi
Keyword(s):  
Dosage Form ◽  
In Vitro Dissolution ◽  
Soluble Form ◽  
Ir Absorption ◽  
Stoichiometric Ratio ◽  
Design Development ◽  
Formulation Development ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Pharmaceutical Cocrystal

Background and Objective: The top approach to deliver poorly soluble drugs is the use of a highly soluble form. The present study was conducted to enhance the solubility and dissolution of a poorly aqueous soluble drug nevirapine via a pharmaceutical cocrystal. Another objective of the study was to check the potential of the nevirapine cocrystal in the dosage form. Methods: A neat and liquid assisted grinding method was employed to prepare nevirapine cocrystals in a 1:1 and 1:2 stoichiometric ratio of drug:coformer by screening various coformers. The prepared cocrystals were preliminary investigated for melting point and saturation solubility. The selected cocrystal was further confirmed by Infrared Spectroscopy (IR), Differential Scanning Calorimetry (DSC), and Xray Powder Diffraction (XRPD). Further, the cocrystal was subjected to in vitro dissolution study and formulation development. Results: The cocrystal of Nevirapine (NVP) with Para-Amino Benzoic Acid (PABA) coformer prepared by neat grinding in 1:2 ratio exhibited greater solubility. The shifts in IR absorption bands, alterations in DSC thermogram, and distinct XRPD pattern showed the formation of the NVP-PABA cocrystal. Dissolution of NVP-PABA cocrystal enhanced by 38% in 0.1N HCl. Immediate release tablets of NVP-PABA cocrystal exhibited better drug release and less disintegration time. Conclusion: A remarkable increase in the solubility and dissolution of NVP was obtained through the cocrystal with PABA. The cocrystal also showed great potential in the dosage form which may provide future direction for other drugs.

A modified sol-gel process for multiferroic nanocomposite films

2007 ◽  
Vol 102 (8) ◽  
pp. 083911 ◽  
Author(s):  
Ming Liu ◽  
Xin Li ◽  
Jing Lou ◽  
Shijian Zheng ◽  
Kui Du ◽  
...  
Keyword(s):  
Sol Gel ◽  
Nanocomposite Films ◽  
Sol Gel Process

Study on the Influence Factors of ZnFe2O4 and TiO2 Composite Films Photoelectrocatalytic Properties

2011 ◽  
Vol 287-290 ◽  
pp. 2199-2202
Author(s):  
Gui Qin Hou ◽  
Wen Li Zhang ◽  
Shui Jing Gao ◽  
Xiao Yan Wang
Keyword(s):  
Methyl Orange ◽  
Sol Gel ◽  
Composite Films ◽  
Influence Factors ◽  
Nanocomposite Films ◽  
Gel Method ◽  
Sol Gel Method ◽  
Conductive Glass ◽  
Photocatalytic Activities ◽  
Film Layer

The ZnFe2O4 and TiO2 nanocomposite films was prepared by Sol-Gel method on conductive glass, and the influence factors of it’s photoelectrocatalytic performence such as the film layer, pole and voltage was investigated. The results indicated that: the photocatalytic effects of composite films with ZnFe2O4+ TiO2+ ZnFe2O4 was the best. The decomposing ratio of methyl orange with the photoelectrocatalysis of composite films at voltage 0.2-6V all increased unstably.At the same time, the distance from films to pole plank also had the effects on the photocatalytic activities of the films.

Apodized fibre Bragg grating with modulated refractive index change for transmissive gain equalization

Optik ◽  
2011 ◽  
Vol 122 (17) ◽  
pp. 1569-1571
Author(s):  
M.R. Mokhtar ◽  
E.S.A. Rahman ◽  
M. Ibsen ◽  
H.A. Abdul Rashid ◽  
H.Y. Wong ◽  
...  
Keyword(s):  
Refractive Index ◽  
Refractive Index Change ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Index Change ◽  
Gain Equalization

Development of an Optical Fiber Sensor with a D-shaped Fiber Bragg Grating Integrated in a Loop-mirror Optical Fiber Laser as a High Sensitivity Refractometer

2021 ◽  
Vol 32 ◽  
Author(s):  
Binh Pham Thanh ◽  
Thuy Van Nguyen ◽  
Van Hoi Pham ◽  
Huy Bui ◽  
Thi Hong Cam Hoang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Fiber Laser ◽  
Fiber Bragg Grating ◽  
Limit Of Detection ◽  
Optical Fiber Sensor ◽  
High Sensitivity ◽  
Optical Signal ◽  
Bragg Grating ◽  
Loop Mirror

In this paper, we report a new type of refractometer based on a D-shaped fiber Bragg grating (FBG) integrated in a loop-mirror optical fiber laser. This proposed sensor is used in wavelength interrogation method, in which the D-shaped FBG is applied as a refractive index (RI) sensing probe and a mirror to select mode of laser. The D-shaped FBG is prepared by the removal of a portion of the fiber cladding covering the FBG by means of side-polishing technique. The D-shaped FBG sensing probe integrated in a loop-mirror optical fiber laser with saturated pump technique, the characteristics of sensing signals have been improved to obtain stable intensity, narrower bandwidth and higher optical signal-to-noise ratio compare to normal reflection configuration. The limit of detection (LOD) of this sensor can be achieved to 2.95 x 10-4 RIU in the refractive index (RI) range of 1.42-1.44. Accordingly, we believe that the proposed refractometer has a huge potential for applications in biochemical-sensing technique.

Effect of non-annealed and annealed ZnO on the optical properties of PVC/ZnO nanocomposite films

2021 ◽  
pp. 089270572110386
Author(s):  
Ali F Al-Shawabkeh ◽  
Ziad M Elimat ◽  
Khaleel N Abushgair
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Zno Nanoparticles ◽  
Oscillator Strengths ◽  
Nanocomposite Films ◽  
Optical Parameters ◽  
Zno Nanoparticle ◽  
Dispersion Energy ◽  
Optical Susceptibility

The goal of this study was to investigate the optical properties of the prepared polyvinyl chloride (PVC)/zinc oxide (ZnO) nanocomposite films. The PVC/ZnO nanocomposite films consist of the addition of different concentrations with both non-annealed ZnO nanoparticles and ZnO nanoparticles annealed at temperature of 700°C. The PVC/ZnO nanocomposite films by weight concentrations of (0 wt.%, 2.5 wt.%, 5 wt.% and 10 wt.%) have been prepared by the casting method. The optical absorbance and transmittance values of the composites films were measured in the wavelength range between (250 to 1100 nm) at room temperature by using the UV-1800 Shimadzu spectrophotometer. The optical properties (absorption coefficient, dielectric constant, refractive index, and optical conductivity) have been investigated by the ultraviolet (UV) spectrophotometer. The optical parameters (direct optical energy gap, excitation energy for electronic transitions, the dispersion energy, static refractive index, static dielectric constant, optical oscillator strengths, the moments of optical spectrum, linear optical susceptibility, third-order nonlinear optical susceptibility, nonlinear refractive index, high-frequency dielectric constant, the carrier concentration to the effective mass ratio, the long wavelength refractive index and the plasma frequency) were calculated. The results showed that the optical properties behavior of the PVC/ZnO nanocomposite films was found to be dependent on the ZnO concentration, and photon wavelength. In addition, the results of the study show that the optical parameters can be influenced by alter the concentration of the nonannealed and annealed a ZnO nanoparticle in the PVC polymer matrix.

Expansion of Nanosized MgSiO3/Chitosan Nanocomposite Structural and Spectroscopic for Loading Velosef by Nanomaterial Intervention

2021 ◽  
Author(s):  
amal aboelnaga ◽  
talaat Meaz ◽  
amany M elnahrawy
Keyword(s):  
Antimicrobial Activity ◽  
High Performance ◽  
Sol Gel ◽  
Polymerization Process ◽  
Absorption Bands ◽  
Structural Morphology ◽  
Crystallinity Degree ◽  
Chitosan Matrix ◽  
Antimicrobial Studies ◽  
Sol Gel Process

Abstract The aim of this study is to investigate the effect of different doses of Velosef in magnesium silica/chitosan nanocomposite in terms of structural, morphology, optical properties, and bioactivity. Loading Velosef in fine-sized magnesium silica/chitosan is an efficient engineering approach for drug delivery. The sol-gel process was used to prepare magnesium silica fine-sized before being blended into chitosan matrix, which acts as a potential morphogenetic biomaterial. The Velosef/magnesium silica/chitosan nanocomposites were characterized by XRD, TEM, SEM, FTIR, UV-absorption, and antimicrobial studies. The XRD was characteristic of the crystallinity degree of the MgO-SiO2/chitosan/Velosef nanocomposites with three maximum peaks at 26.37°, 33.34o, 36.9°. FTIR results indicated the structural change occurred with the Velosef sol-gel polymerization process. UV-absorbance reveals that the MgO-SiO2/chitosan nanocomposite appeared a high performance for loading Velosef at two absorption bands at 253 and 347 nm. The MgO-SiO2/Chitosan/Velosef nanocomposites showed considerable antimicrobial activity in opposition to the tested representative microorganisms. The maximum antimicrobial activity was obtained with MgO-SiO2/Chitosan against both Escherichia coli and Candida albicans (37 mm), while the minimum antimicrobial activity (30 mm) was recorded against B. mycoides and E. coli with control.

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