Decrease In Optical Energy Gap Research Articles

Impact of annealing temperature on optical, morphological, and surface characteristics of PC/PBT blend exposed to alpha particles

The induced modifications of the optical and surface characteristics in the annealed α-irradiated polycarbonate/polybutylene terephthalate (PC/PBT) blend have been studied in the temperature annealing range from 100 to 200 °C for 15 min. Several techniques have been used to study the changes in chemical composition, optical-electronic transitions, photoemission, contact angle, surface roughness, and hardness of annealed samples comparable to the pristine one. The FTIR spectra exhibit aggregate changes in the band intensities after annealing, indicating the scission and cross-linking of the polymer chains. The intensity of the peaks reduced with α-irradiation but began to increase with increasing annealing temperature. The trend of the function groups found in the annealed samples with the rise in annealing temperature supports the crosslinking mechanism. The UV/Vis spectra revealed that the absorption edges of annealed samples were shifted toward lower photon energy (red shift), reflecting the decrease of optical energy gap from 4 eV to 3.6 eV for direct transition and from 3.8 eV to 3.5 eV for indirect transition at the highest temperature. Further, the number of carbon atoms and the number of carbon clusters increases with the increase in the annealing temperature. The refractive index of the samples decreases from 1.5479 for the pristine sample to 1.4008 for the sample at the highest temperature. Moreover, the dielectric parameters and optical conductivity of the annealed samples were modified after thermal annealing. The PL emission yields are decreased with the increase in annealing temperatures that indicating an enhancement in the non-radiative recombination rate relative to the radiative recombination, which may be due to the increasing in the surface density states. The α-irradiated samples showed a notable increase in contact angle and a notable decrease in surface tension values with increasing the annealing temperatures. The side chain induction, which readily bundles and recombines the annealed parts by raising temperatures, also causes the surface roughness of annealed samples to decrease from 1.099 μm for the pristine sample to 0.696 μm for the annealed sample at the highest temperature. It is noteworthy that there is an increase in the hardness from 10.49 ΜPa for the pristine sample to 41.98 ΜPa for the annealed sample at the highest temperature. This is related to the results of changes in the polymer chains due to the active sites or branching points created by scission, which can lead to cross-linking.

Synthesis and Characterization of (PVA-CoO-ZrO2) Nanostructures for Nanooptoelectronic Fields

Nanocomposites have a wide range of applications, including optical integrated circuits, sensors, coatings, and medical devices. As a result, the purpose of this paper is to prepare a new type of nanocomposites made of polyvinyl alcohol (PVA) with different concentrations (0, 1, 2 and 3) wt% of cobalt oxide and zirconium dioxide (CoO-ZrO2) nanoparticles by using casting method. Microscopic photographs demonstrate the fact that the additive distribution amount of NPs in the polymer was uniform, and (CoO-ZrO2) NPs formed a continuous network within the polymer when the concentration reached 3wt.%. The outcomes of optical properties indicate that the absorbance of nanocomposites improves as the concentrations of cobalt oxide and zirconium dioxide nanoparticles increase while transmittance and the optical energy gap decrease. On the other hand, optical constants of nanocomposites (refractive index, absorption coefficient, extinction coefficient, real and imaginary the dielectric constants) and optical conductivity are increase with increases in the weight percentages of (CoO-ZrO2) nanoparticles. These outcomes demonstrate the (PVA-CoO -ZrO2) NCs use for various optical devices.

Characterization of oxyfluoride glasses doped with rare-earth ions through structural, thermal, and optical application thereof

Novel transparent glasses and glass-ceramics were fabricated by using melt-quenching technique with the following composition: TeO2–WO3–Nb2O5–KF–La2O3 doped with Tm2O3. Different properties and physical parameters of these glasses were investigated. As the concentration of Tm3+ ions increases, the linear refractive index increases while the optical energy gap decreases. With high Tm3+ ion concentration creates nucleation in the glass matrix this was investigated by x-ray diffraction. The Judd-Ofelt parameters used to calculate the electric and magnetic dipole transition probabilities, branching ratios, and radiative lifetimes of various excited states of Tm3+-doped parent glass. The emission cross section values for the 3F4→3H6 transition computed by using the McCumber hypothesis. The stimulated emission cross section σeFL(λ) and gain values of fabricated glass increase with Tm3+ ions. The spectroscopic quality and figure of merit (FOM) gain (σeFL(λ)×τR) factors were evaluated for the prepared transparent glass. Furthermore, the produced glasses were demonstrated to have low OH content and they have high fluoride ion content. These important properties of the glasses and glass-ceramics make them suitable for use in photonic applications.

Structural, optical, morphological and mechanical studies of polyethylene oxide/sodium alginate blend containing multi-walled carbon nanotubes

Multi-walled carbon nanotubes were added to mixture of polyethylene oxide (PEO)/sodium alginate (SA) (70/30 wt.%) films via the casting way. X-ray diffraction exhibited the amorphous behavior of the polymer samples, also showed a decrease in the crystalline ratio after the addition of Multi-walled carbon nanotubes (MWCNTs). Fourier Transform Infrared (FTIR) spectroscopy exhibited changes in intensity of some peaks after embedding of MWCNTs, these changes were related to the interaction between PEO/SA blend and MWCNTs. The optical properties of samples were investigated by ultraviolet and visible (UV/vis) spectroscopy and showed decrease in optical energy gap as the concentration of MWCNTs increased. Scanning electron microscopy (SEM) exhibited a homogeneous growth mechanism which denotes the partial compatibility between the nanocomposite components. The mechanical behavior measurements of the prepared samples showed improvement of the modulus of elasticity and tensile strength after adding MWCNTs. This may be due to interaction and adhesion between MWCNTs and polymeric samples. Present results confirm the advantage of selecting MWCNTs as a nanofiller to improve the optical and mechanical properties of polymeric films.

Role of energy loss-range profile of heavy ions in tailoring the optical properties of polycarbonate

Polycarbonate (PC) samples have been implanted with 115 keV N+, Ar+ and Kr+ at fluences ranging from 5x1014 to 1x1016 ions/cm2 to be employed for optical studies. A Decrease in optical energy gap, enhancement in reflectivity and reduction in transmittance, particularly in UV-region, is observed for all implanted samples. The change in optical properties of PC, first, by keeping energy deposited/cm2 constant (i.e. keeping energy*fluence constant) and then by keeping same depth of penetration for different ions have been analysed in detail. The changes are found to be more prominent for N+ compared to Ar+ and Kr+ when the fluence/energy deposited/cm2 by the ions is same. Further, the energy for N+ is reduced to 46 keV, while for Kr+ it is increased to 200 keV to ensure the same penetration depth for N+, Ar+ and Kr+ in PC. Finally, the results are explained on the basis of energy loss-range profiles of these ions in polycarbonate and through Raman spectroscopy. This study convincingly demonstrates that not only the types of ion species, their energies and fluences, but the total energy deposited by ions and their depth of penetration also plays an important role in tailoring the optical properties of polymeric materials.

Optical Properties and Conductivity of PVA–H3PO4 (Polyvinyl Alcohol–Phosphoric Acid) Film Blend Irradiated by γ-Rays

This study assesses the optical properties and conductivity of PVA–H3PO4 (polyvinyl alcohol–phosphoric acid) polymer film blend irradiated by gamma (γ) rays. The PVA–H3PO4 polymer film blend was prepared by the solvent-casting method at H3PO4 concentrations of 75 v% and 85 v%, and then irradiated up to 25 kGy using γ-rays from the Cobalt-60 isotope source. The optical absorption spectrum was measured using an ultraviolet–visible spectrophotometer over a wavelength range of 200 to 700 nm. It was found that the absorption peaks are in three regions, namely two peaks in the ultraviolet region (310 and 350 nm) and one peak in the visible region (550 nm). The presence of an absorption peak after being exposed to hυ energy indicates a transition of electrons from HOMO to LUMO within the polymer chain. The study of optical absorption shows that the energy band gap (energy gap) depends on the radiation dose and the concentration of H3PO4 in the polymer film blend. The optical absorption, absorption edge, and energy gap decrease with increasing H3PO4 concentration and radiation dose. The interaction between PVA and H3PO4 blend led to an increase in the conductivity of the resulting polymer blend film.

Effect of Germanium Content on the Optical Constants of GexS1-x Thin Films

In this study the alloys Ge xS1-x with different Ge content (x=0, 0.1,0.2 and 0.3) wt.% have been successfully prepared by evacuated quartz tube under vacuum pressure (10−2Torr), whereas Ge xS1-x thin films were prepared by thermal evaporation technique under vacuum (10−5Torr) with (x=0,0.1,0.2 and 0.3). The optical properties measurements shows that the optical energy gap decrease from (3.4 to 3 eV) with the increase of x content, the optical constants declare significant variation with x content variation.

Effect of gamma radiation on the structure and optical properties of polycarbonate-polybutylene terephthalate/silver nanocomposite films

Samples from the PC-PBT/Ag nanocomposite have been exposed to gamma radiation with doses between 2 and 25 kGy. The resultant effect of gamma radiation on the structure and optical properties of PC-PBT/Ag nanocomposite has been investigated using TEM, XRD, FTIR and UV spectroscopy. The gamma irradiation with doses 5–25 kGy causes proper spreading of Ag nanoparticles in the PC-PBT matrix, resulted in an increase in the amorphous phase associated with a decrease in optical energy gap from 3.80 to 2.94 eV. Further, the nanocomposite has a response to color change as the color intensity increases from 0.64 to 4.94.

Influence of ZnO/Ag nanoparticles doping on the structural, thermal, optical and electrical properties of PAM/PEO composite

Zinc oxide nanoparticles (ZnO NPs) had been synthesized via sol-gel and the silver nanoparticles (Ag NPs) had been synthesized via chemical synthesis. The XRD and TEM confirmed the formation of ZnO and Ag nanoparticles. A series of polyacrylamide and polyethylene oxide (PAM/PEO) blend films doped with ZnO NPs and various concentrations of Ag NPs were prepared by the solution casting method. The FTIR spectra and XRD studies indicate the structural changes taking place in the nanocomposites which confirmed the compatibility between ZnO/Ag NPs and pure blend. The optical energy gap decreases by the addition of ZnO and Ag nanoparticles. The TGA data showed that the stability of thermal of the all films enhanced after adding the ZnO and Ag nanoparticles. The dielectric and conductivity of the samples has been carried out by an impedance analyzer in the frequency range of 1.0 Hz–10.0 MHz at RT. It has been viewed that the conductivity raised with addition of the ZnO/Ag NPs due to an increase in the number of charges carrier. The dielectric constant reduces with a raise in the frequency for the samples prepared. These properties illustrate ZnO and Ag NPs doped PAM/PEO nanocomposites samples are a prominent material for potential applications.

Structural, optical, mechanical and dielectric properties of titanium dioxide doped PVA/PVP nanocomposite

We report preparation of Titanium dioxide (TiO2) nanoparticles doped PVA/PVP polymer nanocomposites by solvent casting technique. FTIR spectra and XRD studies signify the structural modifications taking place in the nanocomposites. The optical energy gap decreases by the addition of TiO2 nanoparticles. The mechanical properties such as tensile strength and Young’s modulus are enhanced by the addition of Titanium dioxide (TiO2) nanoparticles. The Fluorescence studies indicate that photoluminescence intensity is maximum for 4 wt% doping concentration of TiO2. The AFM analysis provides information about the surface roughness of the polymer film. The dielectric plot shows that the dielectric constant increases up to 12 wt% doping of TiO2, a further increase in the doping concentration results in the reduction of dielectric constant. The dielectric constant decreases with an increase in the frequency for all the films. The above properties show TiO2 doped PVA/PVP nanocomposite films are a prominent material for potential applications.

Physical and optical properties of CdO B2O3 Bi2O3 TeO2 glass system

The physical and optical properties of xCdO (35-x) B2O3 60Bi2O3 5TeO2 glass system (where, x=10, 20, 30) has been investigated. Thermal stability , density , optical transmittance and the refractive index of these glasses have been studied. It was found that the values of density increase but the values of molar volume and oxygen packing density decrease by increasing CdO content. Also, the thermal stability of all the studied samples increase by increasing CdO content. However, it was found that the values of optical energy gap decrease by increasing CdO content for all the studied samples. While as the values of refractive index, molar polarizability, oxide ion polarizability, optical basicity increase by increasing CdO content. Also, all the studied samples exhibit insulating behavior and become more basic and more polarized by increasing CdO content. The high values of third order nonlinear optical susceptibility for all the studied samples, were found to be in the range (1.408-2.307)x 10-12esu, which is larger than that of pure silica glass. Finally, it has been suggested that all the studied samples are promising materials for nonlinear optical requests.

Ion irradiation induced effects on the optical properties of polymers: a possible correlation with the energy loss profile

In the present study, the samples of CR-39 (monomer composition C12H18O7) have been implanted with 100keV Ar+ and Kr+ ions to different fluencies ranging from 5x1014 to 1x1016 ions/cm2. Further, these samples were subjected to UV-Visible, FTIR and Raman spectroscopic techniques to reveal the change in the optical behaviour of the samples in terms of induced structural changes in the polymer as a result of ion irradiation. The observed decrease in optical energy gap and increase in refractive index of the material under study after irradiation to Ar+ and Kr+ ions at the same energy have been tried to explain in terms of the energy loss profile along the trajectory of the respective ions. These studies are quite important towards the development of new materials with desired properties besides their fundamental importance.

Characterization and some physical studies of PVA/PVP filled with MWCNTs

Pristine films of polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) polymer blend filled with gradient contents of (MWCNTs) multi-walled carbon nanotubes have been prepared using ordinary casting technique. Fourier transform infrared (FT-IR) revealed the existence of main characteristic peaks corresponding to vibrational groups that characterized the synthesized samples. The interaction between nano-composite components was indicated by variation of main vibrational bands in the spectral range 1500–1750cm−1. X-ray diffraction (XRD) confirms the structural modification in PVA/PVP matrix due to MWCNTs filling. Transmission electron microscopy (TEM (shows the presence of MWCNTs with a diameter between 80 and 30nm and length of about several micrometers. Scanning electron microscopy (SEM) used to approve the homogenous nature of prepared samples. The absorption coefficient spectra show the appearance of two absorption peaks at 290 and 620nm attributed to n→π* and π→π* electronic transitions. The optical energy gap (Eg) have been obtained from the indirect allowed transition. It was found that, Eg decrease with increasing MWCNTs content. Analysis of refractive index n showed a normal dispersion in the wavelength range 866–2500nm, as well as an anomalous dispersion in the wavelength range 190–866nm. The oscillator parameters (oscillator energy and dispersion energy) were calculated. The decrease in optical energy gap and the increase in refractive index due to filling with MWCNTs suppose the possibility of their use in optical devices.

Physical and optical properties of PbO Bi2O3 B2O3 glasses dopped with FeO.

Abstract The effect of compositional changes on the physical properties of 40PbO 10Bi2O3 (50-0.1)B2O3 xFeO glass system has been investigated. The physical properties include , density ,molar volume,optical electronegativity, optical energy gap, linear refractive index, molar refraction , electronic polorizability ,third order nonlinear susceptibility , have been studied theoretically for 40PbO 10Bi2O3 (50-0.1)B2O3 xFeO glass system where (x= 0.2,0.3,0.4,0.5). An analysis of physical parameters related to these compositions was compared with theoretical predictions. It was found that by increasing FeO content, the glass matrix becomes more dense, and the optical energy gap decrease, but the refractive index increase. The electronic polarizability of oxide ion increase with increasing the optical basicity. The value of optical basicity shows that the glass materials are more basic. It is suggested that the ability of oxide ion to donate electrons to surrounding cations increases. Also, It was found that the values of third order nonlinear susceptibility increase by increasing FeO content and are found to be larger than those of the silica based glasses. The high values of nonlinear refractive index for all the studied samples are advantageous for all optical signal processing and telecommunications. Also, it was found that the values of third order nonlinear susceptibility increase with decreasing the optical energy gap and increasing the refractive index for all the studied samples. Finally, new nonlinear optical materials were suggested.

Physical and properties of Nb2O5 BaO TeO2 glass system with compositional variations

The density calculated decreases with increase of Nb2O5 content from 5.680 g cm-3 to 5.493 g cm-3, this means that , the glass matrix becomes less dense, It was found that , the optical energy gap decrease, but the refractive index increase by increasing Nb2O5 content . The electronic polarizability of oxide ion decrease with decreasing the optical basicity. The value of optical basicity shows that the glass materials are less basic. It is suggested that by increasing Nb2O5 content , the glasses become less polarized. Also, It was found that the values of third order nonlinear susceptibility increase by increasing Nb2O5 content and are found to be larger than those of the silica based glasses. The glasses are found to possess a high refractive index (2.170 – 2.213), a comparatively narrow band gap (3.992 eV – 3.785 eV), high electronic ion polarizability (2.445 A3 -2.546 A3) and high optical basicity (0.987 – 1.014). It was found that the values of the third order nonlinear optical susceptibility are in the range (0.7604-0.9271)x10-12 esu. Finally, all the above values are a good basis for predicting new non linear optical materials.

Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100keVN+ ions at different fluences of 1×1015, 1×1016 and 1×1017ionscm−2 with beam current density of ∼0.65μAcm−2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV–Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33at.% (virgin) to 42at.% at fluence of 1×1017N+cm−2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV–Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12eV (virgin) to 0.25eV (1×1017N+cm−2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV–Visible have been further correlated with the outcomes of the RBS characterization.

Optical spectroscopic investigations on silver doped sodium phosphate glass

This research investigates the optical spectroscopic characteristics of silver-doped phosphate antibacterial glasses with chemical compositions 42P2O5–42ZnO–(16−x) Na2O, (where x = 0, 0.4, 0.8, 1.2, 1.6 Ag2O). The glass samples were prepared by conventional melting quenching techniques. The structures of all the homogenous prepared glasses were studied by XRD, and UV–Vis spectroscopy. The glass formability was tested and the amorphous nature was approved using XRD-technique. Archimedes method has been employed to measure the density of the samples hence, the molar volume was calculated. The molar volume and density shows discontinuity of measurements under effect of increasing Ag2O concentration. The optical spectroscopic analyses for the obtained glass samples has been investigated over the whole range (190–2500 nm) for studying the effect of bandpass absorption glass filter, its color peak center and UV cut-off. Transmittance of some glass samples showed cut-off for UV and short visible wavelengths in some glass samples, so these samples composition can be considered as long-pass edge filters and from band stop ranges started from 190 to 515 nm and increase by increasing doped silver concentration. The optical energy gap decreases by increasing the Ag2O concentration from 4.43 to 3.61 eV. The refractive index and extinction coefficient and some optical properties are studied and the results indicate clearly that there is no high remarkable change with changing wavelength. The refractive index is found to be increased by increasing the Ag2O content. The wavelength dependence of extinction coefficient and the dielectric constants exhibit higher values for higher Ag2O contents.

Structural characterization and calorimetric dissolution behavior of Na2O[sbnd]CuO[sbnd]P2O5 glasses

Two series of glasses belonging to the ternary system Na2O - CuO - P2O5 where copper is introduced differently were synthesized by the conventional melt-quenching technique. Both series start from meta-phosphate composition NaPO3 (50Na2O-50P2O5). In the first series, the Na2O/P2O5 ratio is constant (Na2O/P2O5=1) and both Na2O and P2O5 oxides were replaced by copper oxide CuO: (50-x/2) Na2O - xCuO - (50-x/2) P2O5, 0≤x≤40. In the second series, the molar percentage of P2O5 is kept constant at 50mol% and Na2O is replaced by CuO: (50-x)Na2O – xCuO – 50P2O5, 0≤x≤50. The glasses of these two series belong respectively to NaPO3-CuO and NaPO3-Cu(PO3)2 lines of the ternary system. These materials were characterized by density measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman, diffuse reflectance and dissolution heat measurements carried out with micro-calorimetry technique. Introduction of copper in meta-phosphate glass induces a blue/green color, and strengthens the vitreous network, as shown by the decrease of the molar volume (VM) and the increase of the glass transition temperature (Tg) when the content of CuO rises. The crystallization of the glasses, followed by XRD, leads to the formation of NaPO3, Na2CuP2O7 or Na2Cu(PO3)4 depending on the composition. Raman spectroscopy shows the conservation of the metaphosphate chains for NaPO3-Cu(PO3)2 glasses characterized by a constant O/P ratio (O/P=3) and the depolymerization of these chains for NaPO3-CuO glasses where O/P ratio varies from 0 to 3.67. UV - visible study showed that the optical energy gap decreases by increasing the CuO concentration. Calorimetric study of the dissolution of glasses in acid solution shows a decrease of the dissolution enthalpy, for both series, when the CuO content increases. The dissolution phenomenon is endothermic for glasses with low content in CuO (x<30) and exothermic for glasses rich in CuO.

Change Spectroscopic, thermal and mechanical studies of PU/PVC blends

Blends of polyurethane (PU) and polyvinyl chloride (PVC) with different concentrations were prepared by casting method. The effects of PU on PVC blends was examined by Fourier transform-infrared (FTIR), Ultra-violet visible studies (UV/VIS.), X-ray diffraction (XRD), Thermogravimetric (TGA), Differential scanning calorimetry (DSC), and mechanical properties (stress–strain curve). The interaction between PU and PVC was examined by FT-IR through the absorbance of the N–H groups and was correlated to mechanical/thermal properties. Ultra-violet visible said that optical energy gap decrease with increasing concentration of PU. Differential scanning calorimetry results was observed a single glass transition temperature (Tg) for blends this confirming existence miscibility within the blends. The causes for best thermal stability of some blends may be described by measurements of interactions between C=O groups of PU and the α-hydrogen of PVC or a dipole–dipole –C=O..Cl–C– interactions. Significant alterations in FTIR, X-ray and DSC examination shows an interactions between blends had good miscibility. X-ray shows some alterations in the intensity with additional PU. PU change the mechanical behavior of PVC through of the blends. When polyurethane content increase causes polyvinyl chloride tensile strength decreases and elongation at break increase.

Optical and spectroscopic investigation on Calcium Borotellurite glass system

In this work, the glass formation in Calcium Borotellurite (CBTx) system and their optical properties were studied. Six glass samples were prepared by melt-quenching technique and the samples obtained are transparent, lightly yellowish, without any visible crystallites. The results showed that TeO2 addition increases the density, the electronic polarizability and, consequently, the refractive index. The increase of electronic polarizability and optical basicity suggest that TeO2 addition increases the non-bridging oxygen (NBO) concentration. The increase of TeO2 shifts the band edge to longer wavelength owing to increase in non-bridging oxygen ions, resulting in a linear decrease of optical energy gap. The addition of TeO2 increases the temperature coefficient of the optical path length (dS/dT) in room temperature, which are comparable to phosphate and lower than Low Silica Calcium Alumino Silicate (LSCAS) glasses. The values of dS/dT present an increase as a function of temperature for all the samples measured. The results suggest that CBTx is a good candidate for rare-earth doping and several optical applications.