Spectroscopic Studies of Polypyrrole - PVA Reinforced Iraqi Bentonite Clay Composites

The mixture of Polypyrrole solution with polyvinyl alcohol reinforced Iraqi Bentonite clay are used for preparing a composite that investigated in this study. The weight percentage of bentonite used is 5, 10, 15, and 20 and the particle size selected is less than 75 μm. Composite samples prepared has a thickness of 0.15mm and dimensions of 2.6×2.8 cm2. The optical properties of polymer composites were studied using UV-Vis spectroscopy. The values of optical energy gap decreased from 5.44, 5.41, 5.38 and 5.28 eV for the 5, 10, 15, and 20 wt% of bentonite respectively, and the absorption coefficient increased. The extinction coefficient increases with increasing additive bentonite and decreases as the incident wave length increase. The present work is very important for tailoring the optical response of Polypyrrole – bentonite composites according to specific requirements.

Structural, Optical, and Optoelectrical Studies of Spray Pyrolyzed CuGaSnS4 Thin Films

We deposited CuGaSnS4 thin films on soda-lima glass substrates via a spray pyrolysis process. The X-ray diffraction of CuGaSnS4 films established the formation of an orthorhombic single phase. In addition, the structural parameters of the CuGaSnS4 films were estimated by Debye-Scherer’s formulas, which showed that an enhancement in crystallite size (D) values occurred by increasing the thickness of the investigated films. The EDAX pattern of CuGaSnS4 films confirms a stoichiometric composition. The optical results revealed that the CuGaSnS4 films possessed a direct optical energy gap (Eg). The Eg values were reduced from 1.50 to 1.38 eV with the increase in thickness. Also, there was an observed increase in the linear refractive index and the linear absorption coefficient values occurred due to the increased thickness. Finally, the optoelectrical constants of the sprayed CuGaSnS4 films such as the optical conductivity (σopt) and the optical free carrier concentration to effective mass (N_opt/m^* ) were enlarged with increasing film thickness. The nonlinear optical study showed that the increase in film thickness enhanced the nonlinear optical constants of CuGaSnS4 films. The hot-probe procedure shows that the sprayed CuGaSnS4 films expose p-type conductivity.

Laser induced plasma of cadmium oxide: structural, morphological and optical properties

In this study, the effect of grafting with Iron (Fe) ratios (0.1, 0.3 and 0.5) on the structural and optical properties of cadmium oxide films (CdO) was studied, as these films were prepared on glass bases using the method of pulse laser deposition (PLD). The crystallization nature of the prepared films was examined by X-ray diffraction technique (XRD), which showed that the synthesis of the prepared films is polycrystalline, and Atomic Force Microscope (AFM) images also showed that the increased vaccination with Iron led to an increase in the crustal size ratio and a decrease in surface roughness, The absorption coefficient was calculated and the optical energy gap for the prepared thin films. It was found the absorption decreases and the energy gap decreases with the increase of doping ratio.

Optical and A.C. Electrical Properties for Polypyrrole and Polypyrrole/Graphene (ppy/gn) Nanocomposites

In this work, chemical oxidation was used to polymerize conjugated polymer "Polypyrrole" at room temperature Graphene nanoparticles were added by in situ-polymerization to get (PPY-GN) nano. Optical and Electrical properties were studied for the nanocomposites. optical properties of the nanocomposites were studied by UV-Vis spectroscopy at wavelength range (200 -800 nm). The result showed optical absorption spectra were normally determined and the result showed that the maximum absorbance wave length at 280nm and 590nm. The optical energy gap has been evaluated by direct transition and the value has decreased from (2.1 eV for pure PPy) to (1.3 eV for 5 %wt. of GN). The optical constants such as the band tail width ΔE was evaluated, the value of ΔE for pure PPy was (0.0949eV) while for 5 wt. % of GN it was (0.5156 eV), It has been observed that the Urbach tail for pure PPy was smaller than that for PPy/GN nanocomposites and it increase as GN concentration increases. The A.C electrical conductivity at range of frequency (103Hz-106Hz) was increased by increasing the frequency and GN concentration about four order of magnitude. The s value was about (0.653-0.962) which means that the mechanism of conductivity is correlated hopping mechanism (C. H. P.). The dielectric constant and dielectric lose were determined and found to decrease with increasing frequency.

CuO and MWCNTs Nanoparticles Filled PVA-PVP Nanocomposites: Morphological, Optical, Thermal, Dielectric, and Electrical Characteristics

Copper dioxide (CuO) nanoparticles and Multiwall carbon nanotubes (MWCNTs) filled poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend matrix (50/50 wt%) based polymer nanocomposites (PNCs) (i.e., PVA/PVP:(15-x)CuO(x)MWCNTs for x=0,1,5,7.5, 10,14, and 15wt%) have been prepared employing the solution-cast method. The morphologies of these PNCs are semicrystalline, according to an X-ray diffraction investigation. The FTIR, SEM, and AFM measurements of PNCs were used to investigate the development of the miscible mix, polymer-polymer and polymer–nanoparticle interactions, and the influence of CuO and MWCNTs nanofillers on the morphology aspects on the main chain of PVA/PVP blend. The nanofiller dispersion signposting for x=14 wt% nanoloading in the PVA–PVP blend matrix significantly enhances the crystalline phase, diminishing the optical energy gap to 2.31eV. The DC conductivity values augment with the upsurge in nanofiller level for maximum x=14wt%. The dielectric and electrical characteristics of these PNCs are investigated for an applied frequency range from 1kHz to 1 MHz. The enhancement in the nanofiller level upto x=14wt% in the PVA/PVP matrix leads to the development of percolating network through the PNCs. These factors boost the dielectric permittivity values substantially, owing to the decrease in the nano-confinement phenomenon. The rise in applied frequency reduces dielectric permittivity and impedance values and enhances ac electrical conductivity. These PNCs having good dielectric and electrical characteristics can be used as frequency tunable nanodielectric material in electronic devices.

SYNTHESIS OF CARBON DOTS (CDS) AND DETERMINATION OF OPTICAL GAP ENERGY WITH TAUC PLOT METHOD

Carbon Dots (CDs) which have been synthesized using the laser ablation method show the presence of UV-Vis absorption in the wavelength range of 303 nm to 333 nm for absorbance and 495 nm to 503 nm for fluorescence. Changes in the time duration 1, 2, 3 hours of CDs resulted in changes in the optical energy gap. The optical energy gap valuesare distinguished by the type of indirect transition (n=2) is 3.40 eV (1 hour), 3.15 eV (2 hour), 2.85 eV (3 hour) and direct transition (n=1/2) is 2.58 eV (1 hour), 2.31 eV (2 hour), 1.70 eV (1 hour).

Vis and NIR Diffused Reflectance Study in Disordered Bismuth Manganate ‒ Lead Titanate Ceramics

This work shows a correlation between light reflectance, absorption, and morphologies of series of (1-x) BM–x PT, (x = 0.0, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24) ceramics composite. The (1-x) BM–x PT showed features of a black mirror with a low optical energy gap. The measured Vis-NIR diffused reflectance enabled the calculation of the energy gap using the modified Kubelka-Munk function. The estimated energy gap was lower than 1.5 eV related to low reflectance in the Vis-NIR range. Moreover, obtained histograms of grains, using scanning electron microscope, enabled the correlation between grains size and amount of lead titanate. We deduced from the ceramics surface morphology that marked porosity also induced reflectivity of low magnitude. We correlated the magnitude of the energy gap with phases of the BM-PT composite and with the electrical conductivity activation energy reported in the literature. Our results findings opened prospect studied materials for optical applications.

Structural, Morphological and Optical Properties of Perfume Atomizer Spray Pyrolysis CdO Thin Films: Effect of Solution Volume

CdO films have been deposited on glass substrates with different solution volume (30, 40 and 50 mL) at 200°C using perfume atomizers spray pyrolysis method. X-ray diffraction studies shows that the prepared thin film had cubic and polycrystalline nature. Scanning electron microscope shows the influence of solution volume on surface morphology of the CdO thin film. Optical studies show that in these films the electronic transition is of the direct transition type. The optical energy gap for the films of as deposited are vary from 2.12 to 2.00 eV with solution volume. Photoluminescence results analysis confirmed that the dependence of optical energy gap on solution volume. The Hall measurements were carried out and the results were discussed.

Heat Treatment at Different Temperatures and its Effect on the Optical Properties of Pure PMMA and PMMA-Coumarin

The effect of thermal treatment on optical constants of pure PMMA and with addition (15 and 35) ml of coumarin at different temperatures (100, 110 and 120) C0 for 1 hour were investigated. Cast method used to prepares films of pure PMMA and PMMA with (15 and 35) of coumarin. UV/VIS spectrometer technique used to measure the absorption spectra for these films. The optical constant (absorption spectra and absorption coefficient) don’t changes after applied temperatures in pure PMMA film but the optical constant (absorption spectra and absorption coefficient) in PMMA with (15 and 35) ml of coumarin increased with applied temperatures. The optical energy gap of pure PMMA and PMMA with (15 and 35) ml of coumarin slightly decreased after applied temperature up to 1200 C.