scholarly journals Influence of Erbium Ions on the Optical and Structural Properties of Polyvinyl Alcohol

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Taymour A. Hamdalla ◽  
Taha A. Hanafy ◽  
Ashraf E. Bekheet
Keyword(s):  
Refractive Index ◽  
Polyvinyl Alcohol ◽  
Aqueous Solutions ◽  
Ftir Spectroscopy ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Measurement ◽  
Optical Parameters ◽  
Erbium Ions ◽  
Erbium Chloride

Polyvinyl alcohol (PVA) films doped with erbium chloride (ErCl3) have been prepared by casting from their aqueous solutions. The structure of the doped samples as well as the interactions between the host PVA and Er+3was investigated using FTIR spectroscopy. The optical measurement was recorded at room temperature in the range from 200 nm to 2000 nm. FTIR measurements revealed that Er+3forms complex configuration within the PVA structure. PVA doped with 9 wt% of ErCl3exhibits energy gap and refractive index of 5.1 eV and 1.72, respectively. The effect of the doping increment of ErCl3on the optical parameters has been discussed.

scholarly journals Estimation of optical parameters of silicon single crystals with different orientations

2019 ◽  
Vol 37 (1) ◽  
pp. 65-70
Author(s):  
M.M. El-Nahass ◽  
H.A.M. Ali
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Single Crystals ◽  
Energy Gap ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
High Frequency Dielectric Constant ◽  
Single Oscillator Model ◽  
Indirect Allowed Transition ◽  
Single Oscillator

AbstractOptical properties of Si single crystals with different orientations (1 0 0) and (1 1 1) were investigated using spectrophotometric measurements in a spectral range of 200 nm to 2500 nm. The data of optical absorption revealed an indirect allowed transition with energy gap of 1.1 ± 0.025 eV. An anomalous dispersion in refractive index. The normal dispersion of the refractive index was discussed according to Wemple-DiDomenico single oscillator model. The oscillator energy Eo, dispersion energy Ed, high frequency dielectric constant ∈∞, lattice dielectric constant ∈L and electronic polarizability αe were estimated. The real ∈1 and imaginary ∈2 parts of dielectric constant were also determined.

Influence of Incorporation of Gallium Oxide Nanoparticles on the Structural and Optical Properties of Polyvinyl Alcohol Polymer

2021 ◽  
Author(s):  
Alaa Abd-Elnaiem ◽  
Taymour Hamdalla ◽  
Seleim Seleim ◽  
T. Hanafy ◽  
Mushari Aljouhani ◽  
...  
Keyword(s):  
Refractive Index ◽  
Polyvinyl Alcohol ◽  
Gallium Oxide ◽  
Nonlinear Optical ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Oxide Nanoparticles ◽  
Optical Parameters ◽  
Casting Technique ◽  
Single Oscillator Model

Abstract In the present work, gallium oxide nanoparticles (nGa2O3) are synthesized via the thermal microwave combustion method, while nanocomposites of polyvinyl alcohol (PVA) polymer with various concentrations of nGa2O3 (0, 1, 2, 3, 4, and 5 wt%) are prepared by the casting technique. The structural characterization of nGa2O3, PVA, and films of PVA-Ga2O3 nanocomposites are studied using X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), and Fourier-transform infrared spectroscopy. The HRTEM and XRD examinations showed that the prepared nGa2O3 has an average crystallite size of ~ 5.6 nm and particle size of ~ 0.9 µm. On another side, the optical transmission spectra were performed in the spectral range 250 to 2500 nm at room temperature. The refractive index, absorption coefficient, and optical bandgap (Eg) were determined using the Wemple-DiDomenico single oscillator model. It was shown that Eg slightly reduced from 3.61 to 3.55 eV with increasing the Ga2O3 content to 3 wt%, while raised again up to 3.58 eV for 5 wt% Ga2O3. Other optical characteristics such as the optical density, extinction coefficient, refractive index, optical susceptibility, thermal emissivity, optical sheet resistance for the PVA-Ga2O3 nanocomposites are investigated. The linear and nonlinear optical parameters together with their dependencies on the doping ratio reveals the qualification of PVA-Ga2O3 nanocomposites for nonlinear optical applications.

scholarly journals Studies on Surface Morphology and Electrical Conductivity of PS Thin Films in Presence of Divalent Complexes

2019 ◽  
Vol 16 (3) ◽  
pp. 0588 ◽  
Author(s):  
Al-Taa'y Et al.
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Refractive Index ◽  
Surface Morphology ◽  
Structural Modification ◽  
Energy Gap ◽  
Three Dimensional ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Energy Gaps

       Optical properties and surface morphology of pure and doped Polystyrene films with different divalent metals of Zn, Cu and Sn and one concentration percentage have been studied. Measurements of UV-Vis spectrophotometer and AFM spectroscopy were determined. The absorbance, transmittance and reflectance spectrums were used to study different optical parameters such as absorption coefficient, refractive index, extinction coefficient and energy gap in the wavelengths rang 200-800nm. These parameters have increased in the presence of the metals. The change in the calculated values of energy gaps with doping metals content has been investigated in terms of PS matrix structural modification. The value of optical energy gap was found decreasing from 4.5eV of pure PS to reach 4.45, 4.38 and 4.32eV for Zn, Cu and Sn respectively. Measurement by AFM spectroscopy was done for two and three dimensional topographic images. From figures, the data of roughness average were 7.29, 7.31, 3.37 and 6.73nm for samples (Blank, Zn, Cu and Sn) respectively.

INVESTIGATION OF STRUCTURAL, OPTICAL, AND DIELECTRIC PROPERTIES OF PVA-KI FOR TEMPERATURE SENSOR APPLICATIONS

2019 ◽  
Vol 26 (09) ◽  
pp. 1950054
Author(s):  
T. A. HANAFY ◽  
I. T. ZEDAN ◽  
A. E. BEKHEET
Keyword(s):  
Dielectric Constant ◽  
Temperature Sensor ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Measurements ◽  
Index Formula ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Sensor Applications ◽  
Loss Index

Polyvinyl alcohol (PVA) films doped with potassium iodide (KI) have been prepared by casting from their aqueous solutions. The structure of the doped samples was investigated using Fourier transform infrared spectroscopy. The addition of KI to PVA structure leads to form crosslinking as well as the increase of the amorphous ratio within the investigated sample. The optical measurements were recorded at room temperature in the range of 200–2500[Formula: see text]nm. It was found that the optical energy gap of the investigated sample increases with increasing KI ratio. The effect of the addition increment of KI on the optical parameters of PVA has been investigated. Dielectric spectra of PVA doped with KI were studied in the temperature and the frequency ranges of 303–373[Formula: see text]K and 100[Formula: see text]Hz–5[Formula: see text]MHz, respectively. The behavior of dielectric constant ([Formula: see text]) and dielectric loss index ([Formula: see text]) of PVA sample doped with KI exhibits good linearity with temperature. The obtained results suggest strongly the applicability of these materials in the temperature sensor applications.

DEPENDENCE OF THE OPTICAL AND ELECTRICAL PROPERTIES OF CHEMICALLY ANNEALED VACUUM-DEPOSITED a-Si:H FILMS ON THE DEPOSITION RATE

2012 ◽  
Vol 27 (02) ◽  
pp. 1350015
Author(s):  
AHMED M. EL-NAGGAR
Keyword(s):  
Activation Energy ◽  
Electrical Properties ◽  
Deposition Rate ◽  
Room Temperature ◽  
Energy Gap ◽  
Dark Conductivity ◽  
Optical Parameters ◽  
Optical And Electrical Properties ◽  
Optical Energy Gap ◽  
Optical Energy

The influence of the deposition rate of chemically annealed vacuum-deposited a-Si : H films on its optical and electrical properties was studied. The optical parameters were studied using spectrophotometric measurements of the film transmittance in the wavelength range 200–3000 nm. It was found that with increasing the silicon deposition rate from 0.09 to 0.23 nm/s, the refractive index, n, decreases from 3.78 to 3.45 at 1.5 μm, and the optical energy gap, Eg, decreases from 1.74 to 1.66 eV, while the Urbach parameter, ΔE, increases from 77 to 99 meV. The dark conductivity was measured at temperatures descending from 480 to 170 K. It was found that the room temperature dark conductivity values decreased from 1.11 × 10-6 (Ω⋅ cm )-1 to 2.08 × 10-10 (Ω⋅ cm )-1 with increasing the deposition rate from 0.09 to 0.23 nm/s respectively, while the activation energy Ea increased from 0.53 to 0.84 eV with increasing deposition rate. As a result, a good quality a-Si : H film with optical energy gap of 1.74 eV, Urbach parameter of 77 meV, dark conductivity of 1.11 × 10-6 (Ω⋅ cm )-1, and activation energy of 0.53 eV was successfully prepared at a low deposition rate of 0.09 nm/s.

Preparation and Investigation of  structure, optical , nonlinear optical and thermoelectric properties of  Bi2Se3   thin film

2021 ◽  
Author(s):  
Ahmed Abdel Moez ◽  
H A Elmelgeei ◽  
A I Ali
Keyword(s):  
Thin Film ◽  
Refractive Index ◽  
Electron Microscope ◽  
Dielectric Loss ◽  
Nonlinear Optical ◽  
Energy Gap ◽  
Tangent Loss ◽  
Optical Parameters ◽  
Dispersion Energy ◽  
Nonlinear Optical Susceptibility

Abstract Bi2Se3 thin film were prepared using vacuum thermal evaporation technique. the structure and surface topography for this sample were investigated using both of Diffraction Electron Microscope photos (DEM) and Transmission Electron Microscope (TEM). Bi2Se3 thin film had a direct energy gap which was determined by using measured optical parameters such as optical transmittance (T) and optical reflectance (R). The values for both of the oscillating energy ( Eo) ,dispersion energy (Ed) and ratio of the free carrier concentration on the effective mass (N/m*) were determined optically using the calculated values of refractive index (n). The dielectrical parameters such as dielectric loss (ε\) and dielectric tangent loss dielectric loss (ε\\) were calculated. The density of states (DOS) for both of valence band (Nv) and conduction band (Nc) and also position of Fermi level were determined. The nonlinear optical results such as third-order nonlinear optical susceptibility (χ(3)), nonlinear refractive index (n2) and nonlinear absorption coefficient (βc) were determined. The influence of temperature on IV results were studied, finally the dependence of all of Dispersion factor (D), parallel inductance (Lp) and Seebeck coefficient (S) values on temperature for this film were studied.

scholarly journals Influence of annealing temperature on the structural and optical properties of As30Te70 thin films

2017 ◽  
Vol 35 (2) ◽  
pp. 335-345 ◽  
Author(s):  
A.M. Abd-Elnaiem ◽  
M. Mohamed ◽  
R.M. Hassan ◽  
A.A. Abu-Sehly ◽  
M.A. Abdel-Rahim ◽  
...  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Glass Transition ◽  
Extinction Coefficient ◽  
Chalcogenide Glasses ◽  
Annealing Temperature ◽  
Energy Gap ◽  
Optical Parameters ◽  
Optical Energy Gap

Abstract Chalcogenide glasses have attracted much attention largely due to their interesting physical and chemical properties. Though few published articles exist on the As-Te system, little is known about the optical properties of eutectic or near eutectic composition of As-Te system upon heat treatment. Therefore, this paper reports the effects of annealing temperature on the structural and optical parameters of As30Te70 thin films. The bulk and thin films of 150 nm thick As30Te70 chalcogenide glasses were prepared by melt-quenching and thermal evaporation techniques, respectively. The glass transition and crystallization reactions of the bulk samples were investigated using differential scanning calorimetry (DSC). The influence of annealing temperature on the transformation of the crystal structure was studied by X-ray diffraction (XRD), while the surface morphology of the annealed samples was examined using scanning electron microscope (SEM). The optical band gap, refractive index and extinction coefficient were also calculated. The DSC scans showed that the melting temperature remains constant at 636.56 K. In addition, other characteristic temperatures such as the glass transition temperature, the onset crystallization temperature, and the crystallization peak temperature increase with increasing the heating rate. The crystalline phases for the as-prepared and annealed films consist of orthorhombic As, hexagonal Te, and monoclinic As2Te3 phases. Furthermore, the average crystallite size, strain, and dislocation density depend on the annealing temperature. The optical absorption results revealed that the investigated films have a direct transition, and their optical energy gap decreases from 1.82 eV to 1.49 eV as the annealing temperature increases up to 433 K. However, the refractive index, extinction coefficient, dielectric constant and the ratio of free carrier concentration to its effective mass, increase with increasing the annealing temperature.

scholarly journals Modeling the Optical Properties of a Polyvinyl Alcohol-Based Composite Using a Particle Swarm Optimized Support Vector Regression Algorithm

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2697
Author(s):  
Taoreed O. Owolabi ◽  
Mohd Amiruddin Abd Abd Rahman
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Polyvinyl Alcohol ◽  
Support Vector Regression ◽  
Energy Gap ◽  
Particle Swarm ◽  
Absolute Error ◽  
Support Vector ◽  
Dysprosium Oxide ◽  
External Data

We developed particle swarm optimization-based support vector regression (PSVR) and ordinary linear regression (OLR) models for estimating the refractive index (n) and energy gap (E) of a polyvinyl alcohol composite. The n-PSVR model, which can estimate the refractive index of a polyvinyl alcohol composite using the energy gap as a descriptor, performed better than the n-OLR model in terms of root mean square error (RMSE) and mean absolute error (MAE) metrics. The E-PSVR model, which can predict the energy gap of a polyvinyl alcohol composite using its refractive index descriptor, outperformed the E-OLR model, which uses similar descriptor based on several performance measuring metrics. The n-PSVR and E-PSVR models were used to investigate the influences of sodium-based dysprosium oxide and benzoxazinone derivatives on the energy gaps of a polyvinyl alcohol polymer composite. The results agreed well with the measured values. The models had low mean absolute percentage errors after validation with external data. The precision demonstrated by these predictive models will enhance the tailoring of the optical properties of polyvinyl alcohol composites for the desired applications. Costs and experimental difficulties will be reduced.

scholarly journals Study on some linear and nonlinear optical parameters of glycine hydrofluoride single crystals

2018 ◽  
Vol 36 (4) ◽  
pp. 685-696 ◽  
Author(s):  
A. Abu El-Fadl ◽  
A.M. Abdel-Salam ◽  
A.M. Nashaat
Keyword(s):  
Refractive Index ◽  
Nonlinear Optical ◽  
Grown Crystal ◽  
Elevated Temperatures ◽  
Energy Gap ◽  
Second Harmonic ◽  
Interband Transition ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Tauc Plot

AbstractSingle crystal of glycine hydroflruoride (GHF) was grown from aqueous solution by slow evaporation technique. The structure of the grown crystal was tested and analyzed through X-ray powder diffraction. The functional groups have been identified from the FT-IR spectra. Slabs cut normal to the b-axis from the grown crystal were subjected to incident radiation with a wavelength range of 200 nm to 800 nm to investigate the transmittance and reflectance spectra. Linear optical parameters such as extinction coefficient k, refractive index n and both the real and imaginary parts: ∊real and ∊im of the dielectric permittivity were calculated as functions of the incident photon energy. The dispersion of the refractive index was fitted in terms of Cauchy formula and Wemple-DiDomenico single oscillator model. GHF crystals exhibited indirect optical interband transition and the optical energy gap Eg was determined by using Tauc plot. The indirect band gaps at elevated temperatures were determined and their temperature dependence was estimated. Optical band gap Eg values were found to decrease with an increase in crystal temperature; however, the band tail width exhibited opposite behavior. The nonlinear optical potential was examined by the second harmonic generation (SHG) test.

scholarly journals Temperature Dependence of the Optical Band Gap and Optical Parameters of Tetramethyl Ammonium Tetrachlorozincate (TMA)2ZnCl4 single Crystals Around the Normal and Incommensurate Phase Transitions

2015 ◽  
Vol 9 (1) ◽  
pp. 162-172 ◽  
Author(s):  
A. Abu El-Fadl ◽  
A.M. Nashaat
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Energy Gap ◽  
Optical Transition ◽  
Incommensurate Phase ◽  
Spectral Studies ◽  
Optical Parameters ◽  
Optical Energy Gap ◽  
Optical Energy ◽  
Increasing Temperature

Single crystals of tetramethylammonium tetrachlorozincate [N(CH3)4]ZnCl4 abbreviated hereafter as (TMA)2ZnCl4 were grown using the slow evaporation technique at 315 K. The X-ray powder diffraction patterns indicated that [N(CH)]ZnCl belongs to the orthorhombic system with Pmcn symmetry at room temperature. The lattice constants are found to be a= 12.360 Å, b= 15.687 Å and c= 8.985 Å. The values were in good agreement with the values in previous studies. Ultraviolet–visible–near-infrared (UV–Vis–NIR) spectral studies were carried out in the temperature range 276–307 K. This range of temperature involves two phase transition temperatures (Ti=296 K) from normal (parent) to incommensurate phase and (T=279 K) from incommensurate to commensurate-ferroelectric phase. The cut off wavelength was found to be 195.016 nm at room temperature. The optical transmittance increases with increasing temperature, and the cut off shifts to higher wavelengths. Analysis reveals that the type of optical transition is the indirect allowed one. The optical energy gap (Eg) has the value of 5.903 eV at room temperature. The value of optical energy gap (Eg) decreases with increasing temperature. The changes in the values of the cut off wavelength and optical energy gap (Eg) with changing the temperature were found to take different rates at the two phases under study, besides anomalous takes place at Ti and Tc. The absorption coefficient (α) as a function of the incident photon energy shows an exponential behavior near the absorption edge which suggests that the Urbach rule is obeyed and indicated the formation of a band tail. Urbach parameters were calculated at different temperatures and the frequencies of effective phonons and electron–phonon interaction constants were determined for various phases.

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