scholarly journals Tuning the Refractive Index and Optical Band Gap of Silk Fibroin Films by Electron Irradiation

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
S. Asha ◽  
Y. Sangappa ◽  
Sanjeev Ganesh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Silk Fibroin ◽  
Structural Changes ◽  
Optical Band Gap ◽  
Dielectric Constants ◽  
Visible Absorption ◽  
Optical Responses ◽  
Uv Visible

TheBombyx morisilk fibroin (SF) films were prepared by solution casting method and effects of electron beam on the optical properties and optical constants of the films have been studied by using UV-Visible spectrophotometer. Optical properties like optical band gapEg, refractive indexn, extinction coefficientk, optical conductivityσopt, and dielectric constantsε∗of virgin and electron irradiated films were determined by using UV-Visible absorption and transmission spectra. It was found that the reduction in optical band gap and increase in refractive index with increasing radiation dosage was observed. It is also observed from results that there is increase in dielectric constants with increasing photon energy. The observed optical changes have been tried to be correlated with the structural changes, revealed through FT-IR spectroscopy. The present study is quite important for tailoring the optical responses of SF films as per specific requirements.

scholarly journals Optical Properties of Silver-Vanadium-Phosphate Glasses

2017 ◽  
Vol 16 (1) ◽  
pp. 1-7
Author(s):  
B Eraiah
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Room Temperature ◽  
Optical Band Gap ◽  
Phosphate Glasses ◽  
Vanadium Phosphate ◽  
Tauc Plot ◽  
Uv Visible ◽  
Oxide Ions

The glasses with the composition of xAg2O-50V2O5-(50-x)P2O5 (where x = 5,10,15,20,30 and 40 mol%) were synthesized using melt quenching technique and their optical properties were carried out through UV-Visible spectrophotometer. The absorption spectra of these glasses were recorded at room temperature in the wavelength range 200-1100nm. The optical band gap energies were calculated using Tauc plot. The calculatedenergy band gap values are ranging from 2.075 to 2.834 eV. The refractive index and polarizabilities of oxide ions have been calculated using Lorentz-Lorentz relation. The calculated refractive index and polarizabilities of these glasses in the range of 2.443 to 2.703 and 9.8877×10-24 to 13.590×10-24cm3.

Effects of Nitrogen Doping on Optical Properties of Tungsten Oxide Thin Films

2012 ◽  
Vol 616-618 ◽  
pp. 1773-1777
Author(s):  
Xi Lian Sun ◽  
Hong Tao Cao
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Tungsten Oxide ◽  
Nitrogen Doping ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Tungsten Oxide Thin Films

In depositing nitrogen doped tungsten oxide thin films by using reactive dc pulsed magnetron sputtering process, nitrous oxide gas (N2O) was employed instead of nitrogen (N2) as the nitrogen dopant source. The nitrogen doping effect on the structural and optical properties of WO3 thin films was investigated by X-ray diffraction, transmission electron microscopy and UV-Vis spectroscopy. The thickness, refractive index and optical band gap energy of these films have been determined by analyzing the SE spectra using parameterized dispersion model. Morphological images reveal that the films are characterized by a hybrid structure comprising nanoparticles embeded in amorphous matrix and open channels between the agglomerated nanoparticles. Increasing nitrogen doping concentration is found to decrease the optical band gap energy and the refractive index. The reduced band gaps are associated with the N 2p orbital in the N-doped tungsten oxide films.

scholarly journals Effect of gamma irradiation on structural, morphological and optical properties of p-quaterphenyl thin films

2018 ◽  
Vol 14 (2) ◽  
pp. 5624-5637
Author(s):  
A.A. Attia ◽  
M.M. Saadeldin ◽  
K. Sawaby
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Surface Morphology ◽  
Absorption Coefficient ◽  
Gamma Irradiation ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation Method ◽  
Single Oscillator Model

Para-quaterphenyl thin films were deposited onto glass and quartz substrates by thermal evaporation method. p-quaterphenyl thin films wereexposed to gamma radiation of Cobat-60 radioactive source at room temperature with a dose of 50 kGy to study the effect of ?-irradiation onthe structure and the surface morphology as well as the optical properties of the prepared films. The crystalline structure and the surface morphology of the as-deposited and ?-irradiated films were examined using the X-ray diffraction and the field emission scanning electron microscope. The optical constants (n & k) of the as-deposited and ?-irradiated films were obtained using the transmittance and reflectance measurements, in the wavelength range starting from 250 up to 2500 nm. The analysis of the absorption coefficient data revealed an allowed direct transition with optical band gap of 2.2 eV for the as-deposited films, which decreased to 2.06 eV after exposing film to gamma irradiation. It was observed that the Urbach energy values change inversely with the values of the optical band gap. The dispersion of the refractive index was interpreted using the single oscillator model. The nonlinear absorption coefficient spectra for the as-deposited and ?-irradiated p-quaterphenyl thin films were obtained using the linear refractive index.

scholarly journals Structural and Optical Properties of Sm3+ Doped B-site Ba0.5Rb0.5LaTeO6 Double Perovskites

2019 ◽  
Vol 8 (4) ◽  
pp. 6735-6739
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Solid State Reaction Method ◽  
Tolerance Factor ◽  
Double Perovskites ◽  
Structural And Optical Properties ◽  
Visible Absorption ◽  
Cubic Symmetry ◽  
Uv Visible ◽  
Indirect Band Gap

A double perovskites Ba0.5Rb0.5LaTeO6 and Ba0.5Rb0.5La0.9Sm0.1TeO6 were synthesized by a solid-state reaction method. The structural properties were studied by using the X-Ray powder diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Structural analysis of XRD based on Rietveld refinement indicates that the Ba0.5Rb0.5LaTeO6 and Ba0.5Rb0.5La0.9Sm0.1TeO6 have cubic symmetry with space group Fm m. The tolerance factor of the sample also decreases with Sm3+ substitution. The value obtained from tolerance factor for Ba0.5Rb0.5LaTeO6 and Ba0.5Rb0.5La0.9Sm0.1TeO6 was 0.994 and 0.982 respectively. The optical properties were studied using the UV visible absorption spectroscopy (UV-vis). The Ba0.5Rb0.5LaTeO6 and Ba0.5Rb0.5La0.9Sm0.1TeO6 was assumed to be indirect band gap and the optical band gap obtained for Ba0.5Rb0.5LaTeO6 and Ba0.5Rb0.5La0.9Sm0.1TeO6 were 4.1 eV and 4.3 eV respectively

Properties of TiO2 Thin Film Prepared by Sol-Gel Dip Coating

2015 ◽  
Vol 723 ◽  
pp. 528-531
Author(s):  
Jun Wang ◽  
Ling Yun Bai
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Dip Coating ◽  
Gel Method ◽  
Glass Substrates

TiO2 thin films were prepared on glass substrates by sol-gel method. The effect of withdraw speed on the thickness and optical properties of TiO2 thin films was investigated. The films were transparent in the visible wavelength. The thickness of the TiO2 films was increased from 90 nm for the withdraw speed of 1000 μm/s to 160 nm for the withdraw speed of 2000 μm/s. While, The refractive index of the TiO2 thin film decreased from 2.38 to 2.07. It may be due to the porosity of the film was increased. The optical band-gap of the films was around 3.45 eV.

FP-LMTO study of structural, electronic, thermodynamic and optical properties of MgxCd1−x Se alloys

2014 ◽  
Vol 32 (4) ◽  
pp. 719-728 ◽  
Author(s):  
D. Bensaid ◽  
M. Ameri ◽  
M. El Hanani ◽  
Y. Azaz ◽  
D. Bendouma ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Molar Fraction ◽  
Dielectric Constants ◽  
Ternary Alloys ◽  
Wide Range ◽  
Direct Band ◽  
Extraordinary Refractive Index

AbstractStructural, electronic and optical properties of MgxCd1−x Se (0 ≤ x ≤ 1) are calculated for the first time using density functional theory. Our results show that these properties are strongly dependent on molar fraction of particular components — x. The bond between Cd and Se is partially covalent and the covalent nature of the bond decreases as the concentration of Mg increases from 0 % to 100 %. It is found that MgxCd1−x Se has a direct band gap in the entire range of x and the band gap of the alloy increases from 0.43 to 2.46 eV with the increase in Mg concentration. Frequency dependent dielectric constants ɛ1(ω), ɛ2(ω) refractive index n(ω) are also calculated and discussed in detail. The peak value of refractive indices shifts to higher energy regions with the increase in Mg. The larger value of the extraordinary refractive index confirms that the material is a positive birefringence crystal. The present comprehensive theoretical study of the optoelectronic properties of the material predicts that it can be effectively used in optoelectronic applications in the wide range of spectra: IR, visible and UV. In addition, we have also predicted the heat capacities (CV), the entropy (S), the internal energy (U) and the Helmholtz free energy (F) of MgxCd1−x Se ternary alloys.

scholarly journals Fabrication and Optoelectronic Properties of Fluoride Tin Oxides/Porous Silicon/p-Silicon Heterojunction

2014 ◽  
Vol 36 ◽  
pp. 142-152 ◽  
Author(s):  
Hasan A. Hadi
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Porous Silicon ◽  
Band Gap ◽  
Tin Oxide ◽  
Optical Band Gap ◽  
Spray Pyrolysis Technique ◽  
Tin Oxides ◽  
Uv Visible ◽  
P Type

In this paper, formation of a nanostructure semi transparence fluoride tin oxides (FTO) by spray pyrolysis technique on porous silicon PS layer. Porous silicon PS layer was prepared by anodization of p-type silicon wafers to fabricate of the UV- Visible Fluoride-doped tin oxide /Porous silicon /p-Si heterojunction photodetector. Optical properties of FTO thin films were measured. The optical band gap of 3.77 eV for SnO2:film was deduced. From (I-V) and (C-V) measurements, the barrier height for FTO/PS diode was of 0.77 eV, and the built in voltage , which was of 0.95 V. External quantum efficiency was 55 % at 500 nm which corresponding to peak responsivity of 1.15 A/W at 1 V bias. The PS band gap in the vicinity of PS/c-Si heterojunction was 1.38 eV.

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

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