Optical properties of ternary zinc magnesium phosphate glasses

Ternary phosphate glasses of the system (ZnO)₃₀(MgO)_x(P₂O₅)_70−x with x ranging from 5 to 20 mol% were prepared by melt quenching technique. The optical absorption spectra of these glasses were measured at room temperature in the wavelength range between 190 and 1100 nm while the refractive index at wavelength 632.8 nm. The optical absorption indicates that the electronic transition is indirect and associated with phonon-assisted transition. From the absorption spectra, the optical energy band gap (E_opt) and Urbach energy (E_U) values for all the glass samples were calculated from their ultraviolet edges. The values of E_opt is found to increase from 3.36 to 3.44 eV and values of E_U decrease from 0.47 to 0.29 eV with the increase of MgO content. Variation in these optical parameters, density and molar volume is discussed and correlated with the structural changes within the glassy matrix.     

Electron spin resonance and optical studies of poly(methylmethacrylate) doped with CuCl2

Poly(methyl methacrylate) doped with CuCl₂ was prepared and its electron spin resonance (ESR) spectra and optical properties were studied. The ESR spectra can be accounted for by the presence of two radicals: R_a and R_b. FTIR spectroscopy reveals that there is no main difference of the spectra due to the addition of CuCl₂. The structural modifications are identified by investigating the doping level dependence of the peak heights of certain IR absorption peaks. The optical absorption, transmittance, and reflectance measurements were performed for prepared samples. The doping level (W) dependence on the g‐factor (g), asymmetry factor (A), peak‐to‐peak separation (ΔH_pp), spin concentration (N), optical energy gap (E_opt), Urbach energy (E_u), refractive index (n), average oscillator wavelength (λ_o), and average oscillator strength (S_o) were estimated. It was found that these parameters are changed with doping level. These changes suggest high sensitivity of these films to doping that would suggest the applicability in magnetic and/or optical devices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure,electrical and optical properties of (PVA/LiAsF6) polymer composite electrolyte films

In this work, Li⁺ ion conducting polymer composite electrolyte films (PECs) were prepared based on poly (vinyl alcohol) (PVA), lithium hexafluoro arsenate (LiAsF₆), and ceramic filler TiO₂ using solution cast technique. The XRD and FTIR spectra were used to determine the complexation of the PVA polymer with LiAsF₆ salt. The ionic conductivities of the (PVA + LiAsF₆) and (PVA + LiAsF₆ + TiO₂) films have been determined by the A.C. impedance measurements in the temperature range 320–440 K. The maximum conductivity was found to be 5.10 × 10^?4 S cm^?1 for PVA:LiAsF₆ (75:25) + 5 wt% TiO₂ polymer composite film at 320 K. The calculation of Li⁺ ion transference number was carried out by the combination of A.C. impedance and D.C. polarization methods and is found to be 0.52 for PVA:LiAsF₆ (75:25) + 5 wt% TiO₂ film. Optical properties such as direct energy gap, indirect energy gap, and optical absorption edge values were investigated in pure PVA and salt complexed PVA films from their optical absorption spectra in the wavelength range of 200–600 nm. The absorption edge was found at 5.76 eV for undoped film, while it is observed at 4.87 and 4.70 eV for 20 and 25 wt% LiAsF₆ doped films, respectively. The direct band gaps for these undoped and salt doped PVA films were found to be 5.40, 5.12, and 4.87 eV, respectively, whereas the indirect band gaps were determined as 4.75, 4.45, and 4.30 eV. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Optical parameters and absorption studies of UV‐irradiated azo dye‐doped PMMA films

PMMA and PMMA films doped with different contents of azo dye have been made by using the casting technique. The absorption spectral analysis showed that the doped films have two absorption bands attributed to the π‐π* and n‐π* transition of chromophore groups. These bands disappear upon UV‐irradiation, suggesting that the studied system undergoes a photo degradation process. The absorption coefficient and optical energy gap (E_g) have been obtained from the absorption edge in the 200–900 nm range. It was found that E_g decreases with increasing doping levels, whereas it increases with increasing irradiation time. The width of the tail of localized states in the band gap (ΔE) was evaluated using the Urbach edge method. Some optical parameters were determined from the reflection and transmission spectra in the spectral range of 200–2500 nm. The dependence of the refractive index on irradiation time and doping level have been discussed. It was found that the photo‐induced refractive index changes are very large. These changes suggest the applicability of the studied system in optical devices. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Structural alterations of polycarbonate/PBT by gamma irradiation for high technology applications

In this work, polycarbonate/polybutylene terephthalate (PC/PBT) was irradiated with different gamma doses ranging from 200 kGy to 1950 kGy. Structural alterations of irradiated PC/PBT polymer blend have been studied using UV–vis spectroscopy, X-ray diffraction, and Fourier transform infrared (FTIR), as well as surface wettability. The results of UV–vis spectra showed that gamma irradiation induced an increase in the optical absorption with an increase in the gamma doses with shift in the optical absorption edge in the irradiated samples toward the higher wavelength. This shift is correlated with the decrease in optical band gap energy. Optical band gap decreases up to 12 and 20% with respect to pristine sample for direct and indirect transition, respectively. The number of carbon atoms per conjugated length has been estimated. The α phase and β phase of the crystalline PBT structure were observed. The α phase reflections are slightly increased due to the irradiation but the accompanying α to β transformation alters the results. FTIR investigation showed slight variation in the absorption spectrum specially in the range from 1300 to 1001 cm^?1 which are related to the O–C–O arrangements that is found to be the most affected part of the molecule by irradiation. A remarkable increase was observed in the wettability, surface free energy, and adhesion work of irradiated samples with an increase in the gamma doses.     

Optical and Microwave Dielectric Properties of Phase Pure (K0.5Na0.5)NbO3 Thin Films Deposited by RF Magnetron Sputtering

(K_0.5Na_0.5)NbO₃ (KNN) thin films have been deposited onto Pt/Ti/SiO₂/Si and quartz substrates by RF magnetron sputtering. The films were deposited at 400°C with the variation in oxygen mixing percentage (OMP) ratio from 0% to 100% and annealed at 700°C in oxygen atmosphere. The crystallinity of the films is found to be increased with increased OMP. Dielectric properties of the films were examined over the frequency range from 1 kHz to 1 MHz and the temperature range of 30°C to 400°C. The Curie temperature of the films was found to be in the range 369°C–373°C. For the first time, the split postdielectric resonator (SPDR) method was used to measure the microwave (10–20 GHz) dielectric properties of KNN thin films. The optical properties of as‐deposited and annealed KNN thin films were investigated by means of transmittance spectra. The optical bandgap is calculated by using the Tauc relation, and found to be in the range 4.34–4.40 eV and 4.29–4.37 eV for the as‐deposited and annealed films, respectively. The refractive index (n_700nm) of the films found to be in the range 1.98–2.01 and 1.99–2.07 for as‐deposited and annealed films, respectively. The refractive index dispersion is analyzed by using Wemple–DiDomenico (W–D) single‐oscillator model. The effect of annealing and OMP on the refractive index, packing density and W–D parameters has been investigated. The average single oscillator energy (E_o) and dispersion energies (E_d) of the annealed KNN thin films are in the range of 6.17–7.16 eV and 18.77–22.19 eV, respectively. AC‐conductivity of the annealed films was analyzed by using double power law. Ag/KNN/Pt thin films followed the ohmic conduction (J ∝ E^α, where α ~1) and the low leakage current density obtained for the deposited at 100% O₂ is 3.14 × 10^?5 A/cm² at 50 kV/cm.     

High energy (150 MeV) Fe11+ ion beam induced modifications of physico-chemical and photoluminescence properties of high-k dielectric nanocrystalline zirconium oxide thin films

This work presents the influence of dominated electronic energy loss over nuclear energy loss induced by swift heavy ion (SHI) irradiation on the physico-chemical, optical and other properties of RF grown zirconium oxide (ZrO₂) thin films. For this purpose, thin films of ZrO₂ grown on glass substrate were irradiated by 150 MeV Fe¹¹⁺ ions with a range of fluence from 2E12 to 5E13 ions/cm² to understand the mechanism of induced modifications and defects generation. The XRD results confirmed that the virgin and irradiated ZrO₂ thin films were crystalline in nature with monoclinic and tetragonal structure. The crystallite size varied from 19.93 nm to 46.43 nm with varying ion fluence. Strain, dislocation density and stacking fault were used to investigate the changes in structural parameters. Tauc's plot method was employed for the quantitative evaluation of optical energy band gap (E_g) that exist in the range of 4.45–4.62 eV. The transmittance (%) of the virgin and Fe¹¹⁺ ions irradiated samples was determined in the range of 35.69–66.09% using UV–Vis. spectroscopy. Further, the refractive index was determined using different methods significantly depends on the optical band gap. The broad PL emission peaks were obtained at 375 nm and 440 nm with the excitation wavelength (λ_ex.) of 300 nm. The variation in PL intensity with increasing ion fluence was attributed to the creation or annihilation of primary or complex defects. FTIR spectroscopy was employed for the analysis of chemical modifications in vibrational bonds of samples and the band obtained 660 cm⁻¹was assigned to the asymmetrically coupled Zr–O–Zr stretching which presents the strong vibration in samples. The band intensity increased up to the fluence 5E12 ions/cm² and decreased at a higher fluence of 1E13 ions/cm². Rutherford backscattering spectroscopy technique was used to determine the thickness (165 nm) of the samples.     

Physical Properties,Optical band gaps and Radiation Shielding Parameters Exploration for Dy<Superscript>3+</Superscript>-doped Alkali/Mixed Alkali Multicomponent Borate Glasses

Six compositions of 1 mol % Dy³⁺-doped multicomponent borate glasses containing single Li₂O, Na₂O, K₂O and mixed Li₂O–Na₂O, Li₂O–K₂O, and Na₂O–K₂O oxides have been synthesized by well-known melt-quenching technique. Following the measured density and refractive index values, various physical parameters were estimated for all the glass samples and differences in them are correlated with structural changes. To explore optical properties like absorption edge (λ_cut-off), optical band gap energy (E_opt), and Urbach energy (ΔE), optical absorption spectra were recorded for all the glasses. The E_g has been calculated using Davis and Mott theory for direct allowed, and indirect allowed transitions and the results were reported. The E_g values are also estimated using absorption spectrum fitting (ASF) method. The optical parameters variations have also been associated with the structural changes occurring in the glasses with different alkali/mixed alkali oxides content presence. The shielding properties of the prepared glasses were studied in terms of effective atomic numbers (Z_eff), mean free path (MFP), half value layer (HVL) and macroscopic effective removal cross-section (Σ_R). From these results, it was found that Potassium (K) glass shows superior gamma ray shielding properties due to a higher value of Z_eff and lower values of both MFP and HVL. These results indicate that the prepared glasses might be utilized in place of some common shielding materials to shield γ-rays and neutrons.     

Low-energy He-ion beam modifications the surface properties of biomaterial

In the present work, ultra-high-molecular-weight polyethylene (UHMWPE) films were irradiated with 130 keV He ions. The fluence of the ion beam was ranged from 1 × 10¹² to 1 × 10¹⁶ cm^?2. The chemical, morphological, and crystallite structure changes resulted from the ion bombardment were obtained using different spectroscopic techniques. These techniques were Fourier transform infrared spectrometer, scanning electron microscope, X-ray diffraction, and UV–vis spectrophotometry. The surface free energy for untreated and ion-beam-treated samples was determined by means of contact angle measurements of three different liquids. Our results showed a decrease in the crystallinity of UHMWPE and formation of C=O groups on the polymer surface for modified samples as well. A remarkable shifting in the UV–vis spectra toward lower energy and increase in the optical absorption were observed as the ion fluence increases. Measurements of the contact angle indicate remarkable increase in the surface free energy as a function of ion fluence.     

Room temperature synthesis of boron nitride thin films by dual-ion beam sputtering deposition

Boron nitride (BN) films are prepared by dual-ion beam sputtering deposition at room temperature (~25 °C). An assisting argon/nitrogen ion beam (ion energy E_i=0–300 eV) directly bombards the substrate surface to modify the properties of the BN films. The effects of assisting ion beam energy on the characteristics of BN films were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectra, atomic force microscopy, and optical transmittance. The density of the B–N bond in the film increased with the increase in assisting ion beam energy. The highest transmittance of more than 95% in the visible region was obtained under the assisting ion beam energy of 300 eV. The band gap of BN films increased from 5.54 eV to 6.13 eV when the assisted ion-beam energy increased from 0 eV to 300 eV.     

EPR and optical studies on binary mixed alkali-alkaline earth oxide borate glasses doped with Cu<Superscript>2+</Superscript> ions

Mixed alkali alkaline earth oxide borate glasses of the composition (25 – x)Li₂O–xK₂O–12.5BaO–12.5MgO–49B₂O₃–1CuO (x = 0, 5, 10, 15 and 20 mol %) were prepared by the melt quenching technique. The X-ray diffractograms of all the glass samples were recorded at room temperature. Peak free X-ray spectra revealed the amorphous nature of all the prepared glasses. Modulated differential scanning calorimetry (MDSC) was used to determine the glass-transition temperature (T _g ). The probable mixed alkali effect was investigated using experimental techniques like density, molar volume, MDSC, electron paramagnetic resonance (EPR), and optical absorption studies. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values indicated that the ground state of \(C{u^{2 + }}is{\kern 1pt} {d_{{x^2} - {y^2}}}\) orbital (²B_1g) and the site symmetry around Cu² is tetragonally distorted octahedral. The variation of g _|| and A _|| as a function of Li₂O content was found to be nonlinear. A broad optical absorption band was observed in all the glasses containing Cu² ions corresponding to ²B_1g → ²B_2g transition. From the optical absorption studies the values of the optical band gap (E _opt) for indirect, direct transitions and Urbarch energy (ΔE) have been evaluated. By co-relating the EPR and optical absorption data, bonding parameters α², β² and β ₁ ² were evaluated.     

Fluorescence and UV techniques for studying neck growth and equilibration processes during latex film formation

Steady state fluorescence (SSF) and UV–visible techniques have been used to study neck growth and equilibration processes during the coalescence of hard latex particles. Latex films were prepared separately by annealing pyrene (P_y) labelled and unlabelled poly(methyl methacrylate) (PMMA) particles above their glass transition temperature. During the annealing processes, the optical clarity of the films increased considerably. Direct fluorescence emission of excited pyrene from labelled latex films was monitored as a function of annealing temperature to detect this change. Void closure temperature (T_c) and time (t_c) were determined at the point where the fluorescence emission intensity became maximal. Below this point, the increase in fluorescence intensity (I_op) against temperature was used to determine the activation energy for viscous flow (ΔH≈47kcalmol⁻¹). The decrease in I_op above the void closure temperature was used to determine the backbone activation energy (ΔE≈44kcalmol⁻¹) for the interdiffusing chains. Unlabelled PMMA particles were used to prepare films for UV–vis measurements. The transmitted photon intensity (I_tr) from these films increased as the annealing temperature was increased. This behaviour was also used to determine the backbone activation energy (ΔE≈35kcalmol⁻¹) for the interdiffusing chains. © Society of Chemical Industry.     

Effects of Si5+ Ion Irradiation on Poly(3-methyl thiophene) Films

Poly(3-methyl thiophene) has been synthesized by the chemical oxidation polymerization method using FeCl₃. The powder has been dissolved in CHCl₃ and thin films of thickness 2 µm are prepared on glass and Si substrates. The polymerization has been confirmed by FTIR spectrum. The films are irradiated by 60 MeV Si⁵⁺ ions at different fluences and modifications in optical, electrical and structural properties are studied. FTIR spectra show methyl group evolution after irradiation. The optical band gap decreases after irradiation and dc conductivity increases four orders of magnitude after irradiation at the highest fluence. The conduction mechanism has been found mainly by band conduction.     

A Two-Dimensional Semiconductive Cu2I2-Based Layered-Structure with Rigid Conjugated Tris-Bidentate Tripodal Schiff-Base Chelator

A two-dimensional (2D) layered structure 1 with (6,3) topology was constructed from Cu₂I₂ dimer and rigid conjugated tripodal tris-bidentate Schiff-base chelator L, wherein Cu₂I₂ dimer acts as a two-connecting inorganic node and L ligand works as a triangular three-connecting synthon. Compound 1 has been well structurally elucidated by single-crystal X-ray diffraction. Solid-state diffuse-reflectance UV–Vis spectra show that compound 1 exhibits a much lower optical band gap (Eg) of 1.85 eV compared to its individual components (Eg(CuI) = 3.1 eV, Eg(L) = 2.87 eV).     

Optical, electrical and discharge profiles for (PVC + NaIO4) polymer electrolytes

A sodium ion conducting polymer electrolyte based on poly (vinyl chloride) (PVC) complexed with NaIO₄ was prepared using a solution-cast technique. Optical properties such as direct and indirect optical energy gap, and optical absorption edge were investigated in pure and doped PVC films from their optical absorption spectra in the 200–600 nm wavelength region. The direct optical energy gap for pure PVC lies at 3.14 eV while it ranges from 2.60 to 3.45 eV for different composition doped films. Similar behavior was observed for the indirect optical energy gap and absorption edge. It was found that the energy gaps and band edge values shifted to higher energies on doping with NaIO₄ up to a dopant concentration of 10 wt%. Measurements of ionic conductivity and transference number were made to investigate the order of conductivity and charge transport in this polymer electrolyte. Transference number values show that the charge transport in this polymer electrolyte is predominantly due to ions (t _ion = 0.93). The conductivity increases with increase in concentration of the salt and with temperature. Using this electrolyte, cells were fabricated and their discharge profiles were studied under constant load. Miscibility studies were performed using X-ray diffraction (XRD) and Fourier Transform Infrared analysis (FT-IR) measurements.     

Effect of Temperature on Kinetics and Adsorption Profile of Endothermic Chemisorption Process: –Tm(III)–PAN Loaded PUF System

Abstract

The sorption behavior of 3.18×10^?6 mol l^?1 solution of Tm(III) metal ions onto 7.25 mg l^?1 of 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated at different temperatures i.e. 303 K, 313 K, and 323 K. The maximum equilibration time of sorption was 30 minutes from pH 7.5 buffer solution at all temperatures. The various rate parameters of adsorption process have been investigated. The diffusional activation energy (ΔE_ads) and activation entropy (ΔS_ads) of the system were found to be 22.1±2.6 kJ mol^?1 and 52.7±6.2 J mol^?1 K^?1, respectively. The thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) were calculated and interpreted. The positive value of ΔH and negative value of ΔG indicate that sorption is endothermic and spontaneous in nature, respectively. The adsorption isotherms such as Freundlich, Langmuir, and Dubinin–Radushkevich isotherm were tested experimentally at different temperatures. The changes in adsorption isotherm constants were discussed. The binding energy constant (b) of Langmuir isotherm increases with temperature. The differential heat of adsorption (ΔH_diff), entropy of adsorption (ΔS_diff) and adsorption free energy (ΔG_ads) at 313 K were determined and found to be 38±2 kJ mol^?1, 249±3 J mol^?1 K^?1 and –40.1±1.1 kJ mol^?1, respectively. The stability of sorbed complex and mechanism involved in adsorption process has been discussed using different thermodynamic parameters and sorption free energy.     

Propane Ammoxidation Over the Mo�CV�CTe�CNb�CO M1 Phase: Reactivity of Surface Cations in Hydrogen Abstraction Steps

Density functional theory calculations (GGA-PBE) have been performed to investigate the adsorption of C₃ (propane, isopropyl, propene, and allyl) and H species on the proposed active center present in the surface ab planes of the bulk Mo?CV?CTe?CNb?CO M1 phase in order to better understand the roles of the different surface cations in propane ammoxidation. Modified cluster models were employed to isolate the closely spaced V=O and Te=O from each other and to vary the oxidation state of the V cation. While propane and propene adsorb with nearly zero adsorption energy, the isopropyl and allyl radicals bind strongly to V=O and Te=O with adsorption energies, ??E, being ???1.75 eV, but appreciably more weakly on other sites, such as Mo=O, bridging oxygen (Mo?CO?CV and Mo?CO?CMo), and empty metal apical sites (??E > ?1 eV). Atomic H binds more strongly to Te=O (??E ?? ?3 eV) than to all the other sites, including V=O (??E = ?2.59 eV). The reduction of surface oxo groups by dissociated H and their removal as water are thermodynamically favorable except when both H atoms are bonded to the same Te=O. Consistent with the strong binding of H, Te=O is markedly more active at abstracting the methylene H from propane (E _a  ?? 1.01 eV) than V=O (E _a  = 1.70 eV on V⁵⁺=O and 2.13 eV on V⁴⁺=O). The higher-than-observed activity and the loose binding of Te=O moieties to the mixed metal oxide lattice of M1 raise the question of whether active Te=O groups are in fact present in the surface ab planes of the M1 phase under propane ammoxidation conditions.     

Nonlinear optical properties of poly‐ortho‐toluidine films implantated by N+ ions with different energy

This article reports experimental work on the effect of N⁺ ion implantation on third‐order nonlinear optical properties of POT films. Using K₂Cr₂O₇ as oxidizing agent, poly‐ortho‐toluidine (POT) was synthesized in 1 M hydrochloric. The POT films were prepared by spin‐coating method and then implantated by N⁺ ions (15–30 KeV) at a dose 1.9 × 10¹⁶ ions/cm². The films were characterized by FT‐IR spectroscopy, visible spectroscopy and SEM, their third‐order nonlinear optical susceptibility (χ⁽³⁾) were also examined by a degenerate four‐wave mixing (DFWM) system at 532nm. Compared to pristine POT films, the optical band gap obtained from visible spectra decreased from 3.58 to 3.48 eV when the energy was 30 KeV. Also, The χ⁽³⁾ value of implantated POT films increased from 3.31 × 10⁻¹⁰ esu to 4.04 × 10⁻⁹ esu when the implantated energy was 25 KeV. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Dispersion parameters of cadmium chloride doped PVA-PVP blend films

Solution cast films of poly vinylalcohol (PVA) – poly vinylpyrrolidone (PVP) polymer blend, doped with different concentrations (from 0.5 wt% up to 40 wt%) of cadmium chloride (CdCl₂) have been studied by analysing the data recorded using optical (UV-Vis) spectrometry. The modified band structure of PVA -PVP blends doped with CdCl₂ has been studied using Moss model and Wemple - DiDomenco model. Optical parameters such as transmittance (T), reflectance (R), refractive index (n), average oscillator energy (E₀), oscillator dispersion energy (E_d), real and imaginary part of dielectric constant (ε_r and ε_i) have been determined. The ratio of charge carrier concentration to effective mass (N/m^*), plasma frequency (ω_p), average oscillator wavelength (λ_o), oscillator strength (S_o), optical conductivity (σ) and optical momenta of spectra (M_?1 and M_?3) have been estimated for the PVA-PVP blend films doped with CdCl₂.     

Coordination Polymeric Chain Assemblies of Some Metal Ions with BHQPP

A few coordination chain polymeric assemblies of the type [M(H₂L)(H₂O)₂]_n·xH₂O [where M = Mn(II), Cu(II) and Zn(II) x = 1; Co(II) and Ni(II) x = 2, H₂L = 2,2′-bis-4-[(8-hydroxy-5-quinoline methylenoxy) phenyl] propane] (BHQPP) have been investigated. Structural and spectroscopic properties have been determined by elemental analyses, infrared spectra, electronic spectra, magnetic measurements and thermo-gravimetric analyses. Magnetic moment and reflectance spectral studies reveal that an octahedral geometry is present in all the prepared coordination polymers. The kinetic parameters such as order of reaction (n) and the energy of activation (Ea) were determined using the Freeman–Carroll method. The pre-exponential factor (A), the activation entropy (ΔS^#), the activation enthalpy (ΔH^#) and the free energy of activation (ΔG^#) have been calculated.