scholarly journals Poly Methyl Methacrylate (Pmma) Based Polyaniline Composite for Ammonia (Nh3) Gas Sensors

2021 ◽  
pp. 172-190
Author(s):  
Muktikanta Panigrahi ◽  
◽  
Basudam Adhikari ◽  
Keyword(s):  
Band Gap ◽  
Band Gap Energy ◽  
Dc Conductivity ◽  
Polymerization Process ◽  
Visible Absorption ◽  
Inorganic Acids ◽  
Pani Composite ◽  
Direct Band ◽  
Uv Visible

Inorganic acids (HCl, H2SO4, and H3PO4) doped-PMMA/PANI composites are prepared by in-situ technique via oxidation-polymerization process. Different techniques such as XRD, FTIR, UV-Visible, four-probe method are used to characterize the composite. Presence of different chemical group of the doped composites is analysed by ATR-FTIR spectroscopic analysis. Charge carrier behaviour of the doped composite is analyzed by UV-Visible spectroscopy. Band gap (Eg) of the doped composites is determined from UV-Visible absorption analysis using Tauc expression. The estimated direct band gap energy (Eg) is found to be 1.93 eV (for HCl doped PMMA/PANI composite), 1.19 eV (for H2SO4 doped PMMA/PANI composite), and 1.71 eV (for H3PO4 doped PMMA/PANI composite), respectively. DC-conductivity is measured with and without magnetic field. Temperature dependent DC conductivity is also measured. In addition, we were discussed the response of ammonia (NH3) gas with polyaniline-based sensor materials.

scholarly journals Synthesis and Photonics Applications of Afzelechin Conjugated Silver Nanoparticles

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1295
Author(s):  
Shahid Ali ◽  
Muhammad Rahim ◽  
Perveen Fazil ◽  
Malik Shoaib Ahmad ◽  
Azeem Ullah ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Band Gap ◽  
Band Gap Energy ◽  
Visible Absorption ◽  
Force Microscopy ◽  
Atomic Force ◽  
Uv Visible ◽  
Size And Morphology ◽  
Average Size ◽  
20 Nm

The silver nanoparticles were synthesized, functionalized with afzelechin and characterized using UV-Visible spectroscopy. A difference of 20 nm was observed in surface plasmon resonance of bare and functionalized silver nanoparticles which indicates afzelechin conjugation with silver nanoparticles. The atomic force microscopy (AFM) technique was used for the determination of the size and morphology of synthesized silver nanoparticles. The afzelechin conjugated silver nanoparticles were spherical and their sizes ranged from 3 to 10 nm with an average size of 8 nm while the bare silver nanoparticles were also spherical and their sizes ranged from 3 to 10 nm with an average size of 6 nm. The average sizes were also calculated by fitting their UV-Visible absorption spectra. Fitting is based on the Mie and Mie Gans models, which deduced that afzelechin conjugated silver nanoparticles were 96.5% spherical and 3.5% spheroidal with an average size of 5 nm while bare silver nanoparticles were 100% spherical with an average size of 4 nm. Both the fitting model as well as the AFM results showed a difference of 3 nm between the sizes of afzelechin conjugated silver nanoparticles while 2 nm differences was observed for bare silver nanoparticles. The band gap energy of afzelechin conjugated silver nanoparticles and bare silver nanoparticles were calculated via Tauc’s equation and were found to be 5.1 eV and 5.4 eV, respectively. A difference of 0.3 eV was observed in band gap energies of afzelechin conjugated silver nanoparticles and bare silver nanoparticles.

Crystal phase induced band gap energy enhancing the photo-catalytic properties of Zn–Fe2O4/Au NPs: experimental and theoretical studies

2019 ◽  
Vol 9 (12) ◽  
pp. 3066-3080 ◽  
Author(s):  
Carlos Alberto Huerta-Aguilar ◽  
Aida Araceli Ramírez-Alejandre ◽  
Pandiyan Thangarasu ◽  
Jesus Angel Arenas-Alatorre ◽  
Ivan Alejandro Reyes-Dominguez ◽  
...  
Keyword(s):  
Band Gap ◽  
Catalytic Properties ◽  
Band Gap Energy ◽  
Crystal Phase ◽  
Theoretical Studies ◽  
Visible Absorption ◽  
Au Nps ◽  
Gap Energy ◽  
Experimental And Theoretical Studies

Au NPs on ZnFe2O4 enhances visible absorption, employed for paracetamol oxidation, where peaks were resolved by 2D HPLC.

scholarly journals Computational Investigation of the Folded and Unfolded Band Structure and Structural and Optical Properties of CsPb(I1−xBrx)3 Perovskites

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 342 ◽  
Author(s):  
Hamid M. Ghaithan ◽  
Zeyad A. Alahmed ◽  
Andreas Lyras ◽  
Saif M. H. Qaid ◽  
Abdullah S. Aldwayyan
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Band Gap ◽  
Spectral Weight ◽  
Band Gap Energy ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Generalized Gradient Approximation ◽  
Direct Band

The structural, electronic, and optical properties of inorganic CsPb(I1−xBrx)3 compounds were investigated using the full-potential linear augmented-plane wave (FP-LAPW) scheme with a generalized gradient approximation (GGA). Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and modified Becke–Johnson GGA (mBJ-GGA) potentials were used to study the electronic and optical properties. The band gaps calculated using the mBJ-GGA method gave the best agreement with experimentally reported values. CsPb(I1−xBrx)3 compounds were wide and direct band gap semiconductors, with a band gap located at the M point. The spectral weight (SW) approach was used to unfold the band structure. By substituting iodide with bromide, an increase in the band gap energy (Eg) values of 0.30 and 0.55 eV, using PBE-GGA and mBJ-GGA potentials, respectively, was observed, whereas the optical property parameters, which were also investigated, demonstrated the reverse effect. The high absorption spectra in the ultraviolet−visible energy range demonstrated that CsPb(I1−xBrx)3 perovskite could be used in optical and optoelectronic devices by partly replacing iodide with bromide.

Properties of CdS Thin Films Grown by Chemical Bath Deposition as a Function of Bath Temperature

2009 ◽  
Vol 609 ◽  
pp. 243-247 ◽  
Author(s):  
H. Moualkia ◽  
S. Hariech ◽  
M.S. Aida
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Chemical Bath Deposition ◽  
Bath Temperature ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Cds Thin Films ◽  
Direct Band

The present work deals with the preparation and characterization of cadmium sulfur (CdS) thin films. These films are prepared by chemical bath deposition on the well cleaned glass substrates. The thickness of the samples was measured by using profilometer DEKTAK, structural and optical properties were studied by X-ray diffraction analysis, and UV-visible spectrophotometry. The optical properties of the films have been investigated as a function of temperature. The band gap energy and Urbach energy were also investigated as a function of temperature. From the transmittance data analysis the direct band gap ranges from 2.21 eV to 2.34 eV. A dependence of band gap on temperature has been observed and the possible raisons are discussed. Transmission spectra indicates a high transmission coefficient (75 %). Structural analysis revealed that the films showed cubic structure, and the crystallite size decreased at a higher deposition temperature.

Tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge

2015 ◽  
Vol 118 (10) ◽  
pp. 105704 ◽  
Author(s):  
Takeshi Inaoka ◽  
Takuro Furukawa ◽  
Ryo Toma ◽  
Susumu Yanagisawa
Keyword(s):  
Band Gap ◽  
Tensile Strain ◽  
Band Gap Energy ◽  
Strain Effect ◽  
Direct Band Gap ◽  
Gap Energy ◽  
Direct Band

scholarly journals Determination of the direct band-gap energy of InAlAs matched to InP by photoluminescence excitation spectroscopy

1997 ◽  
Vol 81 (10) ◽  
pp. 6916-6920 ◽  
Author(s):  
P. Roura ◽  
M. López-de Miguel ◽  
A. Cornet ◽  
J. R. Morante
Keyword(s):  
Band Gap ◽  
Band Gap Energy ◽  
Photoluminescence Excitation ◽  
Direct Band Gap ◽  
Gap Energy ◽  
Direct Band

Optical Properties of PZT, PLZT, and PNZT Thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Chien H. Peng ◽  
Jhing-Fang Chang ◽  
Seshu B. Desu
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Band Gap Energy ◽  
Gap Energy ◽  
Pzt Films ◽  
Direct Band ◽  
Band Transition ◽  
La Doped

AbstractOptical properties were investigated for undoped, La-doped, and Nd-doped Pb(ZrxTi1-x)O3 thin films deposited on sapphire substrates by metalorganic decomposition (MOD) process. Refractive index and extinction coefficient of these films were calculated from transmission spectra in the wavelength range of 300 to 2000 nm. The packing densities of these films were calculated from the refractive index data by using the effective medium approximation. Band gap energies of these films were also reported under the assumption of direct band-to-band transition. The refractive index and band gap energy of PZT films showed a linear dependence on Zr/Ti ratio. The refractive index decreased, while the band gap energy increased with increasing zirconium content. It was also found that both La-doped and Nd-doped PZT films had higher refractive indices than those of undoped PZT films with the same Zr/Ti ratio (50/50).

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

Effect of 2,4-dinitrophenol dye doping on tristhioureazinc(II) sulfate single crystals: a potential nonlinear optical material

2020 ◽  
Vol 53 (4) ◽  
pp. 972-981 ◽  
Author(s):  
G. Durgababu ◽  
G. J. Nagaraju ◽  
G. Bhagavannarayana
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Single Crystals ◽  
Nonlinear Optical ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Optical Range ◽  
Gap Energy ◽  
Uv Visible ◽  
Crystalline Matrix

Good quality single crystals of 2,4-dinitrophenol (DNP)-doped tristhioureazinc(II) sulfate (ZTS) were successfully grown by employing the simple and cost effective slow-evaporation solution technique. To study the effect of doping on various device properties, the grown single crystals were subjected to powder X-ray diffraction (PXRD), high-resolution XRD, thermogravimetric analysis (TGA), Vickers hardness testing, and UV–visible, photoluminescence (PL) and Fourier transform IR (FTIR) spectroscopy techniques. The crystal structure of DNP-doped ZTS bulk single crystals remained the same as the crystal structure of ZTS. However, the changes in intensities of the diffraction peaks in the PXRD spectra indicated the incorporation of dopants into the crystalline matrix. FTIR studies confirm the incorporation of dopants into the crystalline matrix, shown by the shifting of certain prominent absorption bands towards higher energy. This also indicated the induced useful strain due to doping, leading to charge transfer and the enhancement of nonlinear optical properties. The cut-off wavelength and optical band gap energy of pure ZTS and DNP-doped ZTS crystals were studied by UV–visible absorption spectroscopy, revealing a slight reduction in the optical band gap energy due to doping, which in turn revealed the enhancement of the optical range. PL studies revealed an enhanced optical range of photoluminescence in ZTS crystals. Second harmonic generation (SGH) studies carried out by the Kurtz powder technique revealed the enhancement of SHG value due to DNP doping. To ensure the thermal stability and mechanical strength of the grown crystals with doping (required from the point of view of device applications), TGA and Vicker's hardness studies were performed.

MBE Growth and Optical Properties of ZnSeO

2002 ◽  
Vol 744 ◽  
Author(s):  
Y. Nabetani ◽  
T. Mukawa ◽  
Y. Ito ◽  
T. Kato ◽  
T. Matsumoto
Keyword(s):  
Band Gap ◽  
High Energy ◽  
Band Gap Energy ◽  
Rf Plasma ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
Mbe Growth ◽  
Vegard’S Law ◽  
Peak Energy

ABSTRACTZnSeO alloy was successfully grown by molecular beam epitaxy on GaAs substrate using RF plasma. The crystal structure of epitaxial ZnSeO alloy was zincblende. No phase separation was observed by in-situ reflection high energy electron diffraction and X-ray diffraction measurements. O composition was estimated by lattice constant assuming Vegard's law. Photoluminescence intensity was larger than that of ZnSe. The peak energy shifted toward lower energies by increasing O composition. The band gap energy determined by photoluminescence excitation decreased with increasing O composition. The bowing parameter was obtained as high as 8.2eV. This large band gap bowing widens controllable energy range of II-VI semiconductor.

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