Direct Optical Band Gap Value Research Articles

Chemical bath deposited CdTe thin film: Optical, electrical, and photoresponse aspects

Owning a narrow bandgap, remarkable optical and electrical properties with notable stability has made cadmium telluride (CdTe) an immensely vital semiconductor to develop cutting-edge optoelectronics. Taking these properties in to account, CdTe thin film is deposited employing the chemical bath deposition (CBD) technique. The X-ray diffraction analysis of the as-deposited thin film unveiled the composite crystalline structure, incorporating cubic, hexagonal, and tetragonal phases. The energy dispersive X-ray analysis and X-ray photoelectron spectroscopy ascertained the chemical composition of CdTe thin film. Distinctive Raman peaks are detected at 141 and 167 cm−1, signifying the presence of Cd-Te bond in the deposited thin film. The comprehensive evaluation of scanning electron micrographs emphasized the firm adhesion of the film to the substrate and displayed a uniform overlay of microstructures resembling rods. The observations from atomic force microscopy unveiled uniform grain structure with topographical features of hills and valleys. The UV-Visible spectroscopic examination elucidated that the as-deposited thin films exhibits a direct optical bandgap value of 1⋅59 eV. Temperature-dependent analysis of d.c. electrical resistivity exhibited a descending pattern, substantiating thin film's semiconducting attributes. The investigation into the photoresponse attributes of the thin film is accomplished by subjecting it to a polychromatic light, green and red monochromatic light source with an intensity of 50 mW/cm² employing three different biasing voltages. The thin film demonstrated maximum photocurrent for red light source than polychromatic and green light with maximum responsivity of 59⋅4 μA/W and detectivity of 17⋅7 × 106 Jones. These findings provide valuable insights on the photoresponse behavior of CBD deposited CdTe thin film in its as-deposited form.

Optical characterization and dispersion analyses of plasma polymerized methyl acrylate thin films

This work reports the structural characteristics, surface morphology, linear and nonlinear optical properties of 110 to 225 nm thick plasma polymerized methyl acrylate (PPMA) thin films. X-ray diffraction analyses confirm the amorphous nature of the films. Field emission scanning electron micrographs of the films display cluster-based surface morphology. Attenuated total reflectance Fourier transform infrared spectroscopy confirms the chemical structural changes in the films. The optical properties were studied based on the absorbance, transmittance, and reflectance spectra measured by an ultraviolet–visible spectrophotometer within the wavelength ranges from 200 to 800 nm. The direct optical band gap and Urbach values are increased from 3.66 to 3.83 eV and 0.28 to 0.45 eV, respectively with increasing film thickness. The extinction coefficient and refractive index were evaluated, and discussed a correlation between the refractive index and the optical bandgap. The real and imaginary dielectric constants, volume/surface energy loss functions and skin depth were deduced. The oscillator energies and parameters were analyzed using the concept of Wemple-DiDomenico and Sellmeier models, respectively for a single oscillator. Static linear refractive index for the studied films exhibits normal dispersion behavior with film thicknesses and satisfied Moss, Ravindra-Gupta, and Herve-Vandamme rules. The linear susceptibility, third-order nonlinear susceptibility and the non-linear refractive index are considerably reduced from 0.20, 29.5 × 10−14 esu, and 5.89 × 10−12 esu with increasing optical band gap energies. The outcomes from the analyses of PPMA demonstrated their potential for usage in electronic, optoelectronic, and non-linear device applications.

Tuning the optical, and dielectric properties of PVC/PEO/NiMoO4/MWCNTs/x wt %PANI blended polymers for optoelectronic applications

Nanoparticles of nickel molybdate (NiMoO4) have attracted significant interest for their application as electrode materials. Here, new hybrid blended polymers, poly (vinyl chloride)/polyethylene oxide/nickel molybdate/multi-walled carbon nanotubes/polyaniline (PVC/PEO/NiMoO4/MWCNTs/x wt %PANI) were prepared. Several techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), diffused reflectance, fluorescence and LCR meter were used to investigate the impact of the different fillers on the structure, electrical and optical features of the PVC/PEO blend. The structures of NiMoO4 and different blends were explored using XRD technique. The linear and nonlinear optical properties and the emitted colors of host blend are found to be affected by NiMoO4, MWCNTs and different amounts of PANI fillers. The T values of PVC/PEO were reduced as it loaded with NiMoO4/MWCNTs/x wt %PANI and it reached its minimum value (21–37% in the visible range) in NiMoO4/MWCNTs/x 0.4 %PANI blend. The minimum direct and indirect optical band gap values (4.09, 4.9) eV and (1.92, 3.47, 3.94) eV, respectively, were obtained as the amount of PANI became 0.4 wt % in the doped blend. The doped PVC/PEO blend with NiMoO4 has the highest refractive index value (2.11) at 600 nm. The highest nonlinear optical parameters were acquired exclusively in the visible spectrum when PVC/PEO was doped with NiMoO4.The maximum energy density value (6.03 × 10−3 J/m3) was obtained when the host blend loaded with NiMoO4/MWCNTs. Thus, PVC/PEO/NiMoO4/MWCNTs/x wt %PANI blends are recognized as a good prospect for UV blocking, solar cell, optoelectronic, nonlinear optical devices and energy storage innovation.

Impact of ZnMn2O4/CdS nanocomposite on the structural, optical and dielectric characteristics of PMMA/PEO blend

Herein, polymethyl methacrylate (PMMA)/ polyethylene oxide (PEO) blend doped with nanocomposite (1 − x) ZnMn2O4/xCdS samples were prepared through two steps, the first comprising nanocomposite (1 − x) ZnMn2O4/xCdS samples synthesizing, while the second was the incorporation of nanocomposites into the blend matrix, and finally the films were obtained through the casting solution method. Various techniques, such as X-ray diffraction, scanning electron microscopy, diffused reflection and impedance spectroscopy were used to determine the change in the PMMA/PEO structure after the inclusion of the nanocomposites. The direct and indirect optical bandgap values for the PMMA/PEO blend decreased from 5.04 and 4.8 eV to 4.99 and 4.7 eV, respectively, as the blend doped with (1 − x) ZnMn2O4/xCdS samples. At 600 nm, the refractive index of the blend was raised from 1.37 to 1.53 as it doped with 0.9 ZnMn2O4/0.1CdS sample. The linear and nonlinear optical parameters grow with the insertion of (1-x)ZnMn2O4/xCdS nanocomposites into the PMMA/PEO blend. Variation of CdS in the doped nanocomposites affects slightly the linear and nonlinear optical parameters of the host blend. Blend containing 10 % CdS has the highest linear and nonlinear optical parameters as compared with other doped blends. All of the blends exhibited different shades of blue color, except for the blend that contained 10 % CdS, which displayed a violet color. The effect of doping on the dielectric properties of different blends was also explored. Blend with 20 % CdS has the highest energy density. This improvement implies the use of prepared blends in different optoelectronic, photocatalytic and storage device applications.

Insights into the structural and optical features of plasma polymerized N, N, 3, 5 tetramethylaniline-2,6-diethylaniline thin films

A capacitively coupled AC (50 Hz) glow plasma has been used to produce plasma polymerized N, N, 3, 5 tetramethylaniline: 2,6-Diethylaniline composite thin films onto precleaned glass substrates at various monomer ratios. The FSEM studies revealed smooth, compact, flawless, and pinhole-free surfaces of the thin films. The energy-dispersive X-ray spectrum confirmed the existence of carbon, nitrogen, and oxygen in the composite thin films. The broadband weak absorption peaks in the FTIR spectra indicated the structural modifications in the plasma polymer caused by the reorganization of two monomer molecules during the plasma polymerization process. The thickness of the composite film increased with rising N, N, 3, 5 tetramethylaniline percentage in the composition, which had an important effect on the optical properties while keeping the polymerization parameter the same for all the deposited films. Decreasing the proportion of N, N, 3, 5 tetramethylaniline monomer results in an increase in both direct and indirect optical band-gap values, from 2.84 to 2.94 eV and 1.74–1.87 eV, respectively. While the Urbach energy values decrease from 0.649 eV to 0.556 eV. From the optical absorbance curve, it was observed that with increasing N, N, 3, 5 tetramethylaniline monomer concentration, the absorbance increased and reached a maximum at this monomer concentration of 75%. We also measured the non-linear optical parameters-steepness parameter, refractive index, extinction coefficient, and dissipation factor to understand the suitability of the composite thin films for advanced optoelectronic devices.

Structural and optical behaviours of methyl acrylate-vinyl acetate composite thin films synthesized under dynamic low-pressure plasma

Low-pressure (33.33 Pa) plasma polymerized methyl acrylate and vinyl acetate composite thin films with various monomer compositions were deposited onto glass substrates. Under the same plasma conditions, the homopolymer thin films were also prepared. The thickness of the composite films was observed to vary between 117 and 213 nm depending on the monomer ratio. The composite films exhibit a smooth, pinhole-free, and immaculate surface morphology, surpassing that of the homopolymers. The energy dispersive x-ray study shows that the films contain mainly carbon and oxygen with 26.09–37.20 at% and 35.03 − 40.10 at%, respectively. The composite films contain more carbon contents which enhance the film stability. The appearance of some broad absorption bands in the Fourier transform infrared spectroscopy indicates structural changes in the PP films caused by the restructuring or dilapidation of monomer molecules while forming the polymer. The UV–visible spectra analysis reveal that the composite films exhibited a tunable optical band gap by adjusting the monomer ratio. The decrease of methyl acrylate monomer reduces the direct and indirect optical band-gap values of composite films from 3.15 to 3.00 eV and 2.35 to 1.74 eV, respectively. While Urbach energy values increases from 0.33 eV to 0.90 eV. All the films showed good transmittance properties (86 − 96%) in the visible range wavelength (550 − 800 nm). Other optical parameters are also found better in composite films which indicates the aptness of the composite films in various optoelectronic or electronic applications.

Studying the optical and thermal properties of Cs/ZnO and Cs/ZnO/GO hybrid nanocomposites

Green nanotechnology, defined as the synthesis or hybridization of nanomaterials with natural bioactive compounds, is a low-cost, eco-friendly, easy-to-manage and non-toxic technology. Nanocomposites have recently gained attention due to their unique characteristics and applications in the fabrication of microelectronic circuits, sensors, piezoelectric devices, optoelectronic components, fuel cells, corrosion surface passivation coatings, and catalysts. Accordingly, chitosan (Cs), a bioactive polymer, was hybridized with nanomaterials including ZnO and graphene oxide (GO) utilizing two easy, eco sustainable, and low-cost methods of preparation. All samples were analyzed using different analytical techniques. The FTIR and NMR results confirmed that the interaction between Cs, ZnO and GO occurs through the NH2 function group of Cs with ZnO and the O of the carboxyl group COOH of GO. Furthermore, the SEM data show the agglomeration generated by ZnO and GO on the Cs surface. According to the optical characterization of hybrid Cs/ZnO/GO, the one-pot preparation method achieves the lowest indirect and direct optical band gap values of 0.176 and 3.18 eV, respectively. Furthermore, it has a larger Eu = 5.46 eV value than the other samples, indicating a higher degree of disorder and high conductivity. Finally, the TGA results showed that hybridization of Cs with ZnO and Go improved the temperature decomposition and degradation of Cs by 79.9%. As a result, the one-pot approach for creating CS/ZnO/GO hybrid nanocomposite is effective for preparing Cs/ZnO/GO as an optoelectronic material.

Enhancement of optical and piezoelectric properties of P(Vinylidene fluoride-hexafluoropropylene)/N,N-Dimethyl-4-nitro-4-Stilbenamine composites for optoelectronic applications

ABSTRACT XRD, FTIR, optical morphology, and UV spectroscopy are used to investigate (PVDF-HFP)/DANS composites. Analysis of XRD and FTIR revealed that β-phase of (PVDF-HFP) is enhanced. UV analysis revealed that, indirect and direct optical bandgap values were decreased from 4.01 to 1.32 eV and from 5.41 to 3.68 eV of pure and dye doped composite samples. Linear and nonlinear optical parameters values are calculated. The piezoelectric properties of (PVDF-HFP)/DANS composite samples have been investigated and the high piezoelectric coefficient value of composite samples (d33 ≈ 44 PC/N) makes us consider these composites as one of the most promising piezoelectric materials.

Role of rubrene additive for reinforcing the structural, optical, and dispersion properties of polyvinyl alcohol films towards optoelectronic applications

A conventional casting method was used to produce promoted polyvinyl alcohol (PVA) films via rubrene additive. The 1.2 g of PVA dissolved in 120 ml of distilled water and doped with various concentrations (0, 0.1, 0.3 and 0.4 wt%) of rubrene dye. The influence of rubrene dopants on the structural properties of PVA was studied using FTIR and XRD techniques. The semicrystalline nature of the PVA polymer was established by the XRD pattern. FT-IR analysis shows changes in peaks intensities of PVA and their widths are expanded in the presence of rubrene dopants which indicates the interactions between the functional groups of PVA and the rubrene dopants. XRD patterns exhibit the existence of rubrene inside the PVA structure leads to form cross-linking which enhances the amorphous nature within the doped PVA samples. The optical characteristics were investigated using spectrophotometric measurements of transmittance T(λ), reflectance R(λ), and absorbance A(λ) in the spectral range of 200–2500 nm. The indirect and direct optical band-gap values of PVA films decreased from 5.15 eV and 5.69 eV to 3.63 eV and 4.50 eV as rubrene doping ratio was increased from 0 to 0.4 wt%, respectively. The refractive index dispersion region was explained using the single oscillator (Wemple–DiDomenico) model. The extracted values of dispersion energy (Ed), dielectric constant at infinite frequency (ε∞) and lattice dielectric constant (εL) of PVA/rubrene composite films increased from 0.74 eV, 1.31 and 1.35 to 5.35 eV, 3.47 and 4.35; respectively, whereas oscillator energy (Eo) decreased from 2.41eV to 2.17 eV as rubrene contents increased from 0 to 0.4 wt%, respectively. Indeed, these changes in values of dispersion parameters is evidence to the cross-linking bonds between the host polymer and the rubrene dopants. The improvement of optical properties of PVA/rubrene films demonstrates their applicability as eco-friendly packaging materials, particularly in flexible optoelectronic and microelectronic devices.

Architecture of a dinuclear Co(II) complex based on 3-amino-1,2,4-triazole-5-carboxylic acid: molecular structure, thermal behavior, optical properties, and DFT calculations

The dinuclear compound [Co2(Hatzc)2(H2O)6](NO3)2·4H2O containing the polytopic ligand Hatzc‒ = 3-amino-4H-1,2,4-triazole-5-carboxylate was synthesized and characterized. Single-crystal X-ray diffraction showed that two monoanionic N,O-chelating Hatzc‒ ligands bridge two Co(II) ions in a µ-N1,N2 fashion. Both Co(II) centers are further coordinated by three H2O ligands making up an octahedral coordination. A complex network of intra- and intermolecular O‒H···O and N‒H···O hydrogen bonding interactions characterize the structure. Hirshfeld surface analysis, ATR–FTIR, and FT-Raman spectroscopy in combination with density functional theory (DFT) calculation of vibrational modes confirm this multitude of H bonds. Thermogravimetric and differential thermal analysis experiments under an argon atmosphere in the temperature range of 25–900 °C showed thermal stability till about 100 °C and multi-step decomposition yielding Co2O3 at about 280 °C. The octahedral environment of Co(II) was confirmed by UV–vis absorption spectroscopy, which shows weak absorption bands at around 520 nm assignable to electronic d‒d transitions alongside with π‒π* transitions dominating the 250–350 nm range. Time-dependent DFT calculated excited states agree very well in terms of energy match with the observed transitions. The direct and indirect optical band gap values were determined using the Tauc plot method to 3.33 eV and 2.75 eV, respectively, indicating semiconducting properties.

Deposition of (Ag,Cu)2Zn(Sn,Ge)S4 thin films on Mo-coated glass substrate by vacuum magnetron sputtering and post-sulfurization techniques

Cation substitution is a useful way to improve the properties of semiconducting Cu2ZnSnS4 thin film. In this work, partial Cu and Sn in Cu2ZnSnS4 are substituted by Ag and Ge, respectively. The (Ag,Cu)2Zn(Sn,Ge)S4 thin films were successfully fabricated using vacuum magnetron sputtering and post-sulfurization techniques. The formation of Ag & Ge co-doped Cu2ZnSnS4 structure with secondary phase is proved by XRD and Raman results. The Ag and Ge ratios depend on the composition of Cu-Ag target and the sputtering time of Ge, respectively. The direct optical band gap values of thin films increase with the increase of Ge content. When the sputtering time of Ge is 90 s, the Urbach energy of (Ag,Cu)2Zn(Sn,Ge)S4 thin films reaches the minimum value of 339 meV, revealing the reduced band tail state by Ge incorporation.

Impact of erbium (Er) doping on the structural and magnetic properties of Ni-Cu (Ni0.1Cu0.9Fe2O4) nanoferrites

Rare earth erbium (Er) doped spinel Ni-Cu nanoferrites having chemical composition Ni0.1Cu0.9ErxFe2-xO4 (x = 0.00, 0.010, 0.015, 0.020, 0.025 and 0.030) were prepared by standard citrate-gel auto combustion (CGAC) technique. X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, and vibrating sample magnetometer (VSM) were used to characterize the structural, optical, and magnetic properties of these ferrites. X-ray diffraction spectra clearly revealed that the pure Ni-Cu ferrite shows a tetrahedral distortion due to John Tellar ion (Cu2+) subsequently erbium doping transformed the tetragonal phase in to the cubic spinel phase with minor traces of impurity phase. Using Scherer's equation, the average crystallite size was found to be between 7.39 and 27.78 nm. The average crystallite size (7.39–27.78 nm) obtained from XRD and average grain size (64.84–83.36 nm) measured from FESEM confirmed the nano structure of prepared samples. Energy dispersive analysis X-ray (EDAX) spectra with elemental analysis verified the existence of Ni, Cu, Er, Fe, and O elements without any impurities. Two prominent absorption bands detected in FTIR spectra within the wave number range of 575.54–586.73 cm−1 (υ1) and 370.24–372.53 cm−1 (υ2) indicate the stretching vibrations of Fe3+-O2− complexes in tetrahedral and octahedral sites of spinel structure respectively. TG and DTA techniques were used to analyze the thermal behavior of the composition x = 0.030. It was observed that exhibiting a rapid loss in weight after 900 °C promotes the formation of pure phase nanoferrite. Direct and indirect optical band gap values were computed from UV absorption studies with Tauc plots. The obtained band gap values revealed the semiconducting behavior of the prepared samples. VSM was used to explore the magnetization of samples as a function of field at temperatures of 15 K and 300 K. The maximum saturation magnetization (Ms) was observed for x = 0.030 composition and it was estimated as 31.18 emu/g at 15 K and 26.80 emu/g at 300 K temperatures. The experimental and theoretical values of lattice parameter and room temperature magnetic moment are good agreement with suggested cation distribution.

Structural, Electrical and Optical Properties of Pyrrolo[1,2-i][1,7] Phenanthroline-Based Organic Semiconductors.

This work reports a study on structural, electrical and optical properties of some recently synthesized pyrrolo[1,2-i][1,7] phenanthrolines derivatives in thin films. The thin films were deposited onto glass substrates by spin coating technique, using chloroform as solvent. The obtained films exhibited a polycrystalline structure with an n–type semiconductor behavior after heat treatment in the temperature range 293–543 K, specific to each sample. The thermal activation energy lies between 0.68 and 0.78 eV, while the direct optical band gap values were found in the range 4.17–4.24 eV. The electrical and optical properties of the investigated organic semiconductor films were discussed in relation to microstructural properties, determined by the molecular structure. The investigated organic compounds are promising for applications in organic optoelectronics and nanoelectronics.

Impact of Sm3+ and Er3+ Cations on the Structural, Optical, and Magnetic Traits of Spinel Cobalt Ferrite Nanoparticles: Comparison Investigation.

In this study, we investigated a comparison of the structure, morphology, optic, and magnetic (room temperature (RT)) features of Er3+ and Sm3+ codoped CoFe2O4 (CoErSm) nanospinel ferrite (NSFs) (x ≤ 0.05) synthesized via hydrothermal (H-CoErSm NSFs) and sonochemical (S-CoErSm NSFs) approaches. The formation of all products via both synthesis methods has been validated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), along with energy-dispersive X-ray (EDX) and transmission electron microscopy (TEM) techniques. The single phase of the spinel structure (except for the Hyd sample with x = 0.03) was evidenced by XRD analysis. The DXRD (crystallite size) values of H-CoErSm and S-CoErSm NSFs are in the 10–14.7 and 10–16 nm ranges, respectively. TEM analysis presented the cubic morphology of all products. A UV–visible percent diffuse reflectance (DR %) study was performed on all products, and Eg (direct optical energy band gap) values varying in the 1.32–1.48 eV range were projected from the Tauc plots. The data of RT magnetization demonstrated that all prepared samples are ferromagnetic in nature. M–H data revealed that rising the contents of cosubstituent elements (Sm3+ and Er3+ ions) caused an increase in Ms (saturation magnetization) and Hc (coercive field) in comparison to pristine samples. Although concentration dependence is significant (x > 0.02), no strict regularity (roughly fluctuating) has been ruled out in Ms values for doped samples prepared via the hydrothermal method. However, sonochemically prepared samples demonstrated that Ms values increase with increasing x up to x = 0.04 and then decrease with the further rise in cosubstituent Sm3+ and Er3+ ions. The calculated values of Ms and Hc were found to be greater in H-CoErSm NSFs compared to those in S-CoErSm NSFs. The present investigation established that the distribution of cations and the variation in crystallite/particle sizes are efficient to control the intrinsic properties of all samples.

Structural, Morphological, and Optical Properties of Cobalt Oxide Thin Films

AbstractCobalt oxide thin films are successfully synthesized by sol‐gel spin coating method. The XRD study shows that the cobalt oxide thin films annealed at 400°C exhibit cubic polycrystalline structure. SEM images show a well adherent and uniform formation of cobalt oxide thin films with nanosized grains‐like morphology. From the optical study, the direct optical band gap values of as‐deposited and annealed cobalt oxide films are found to lie between 1.42–2.05 and 1.36–1.94 eV. The absorption coefficient of the cobalt oxide is found to be in the order of 104 cm−1. High refractive index of cobalt oxide indicates that it can be used as one of the layers in multilayer antireflection coatings.

Investigations on Structural and Optical Properties of Various Modifier Oxides (MO = ZnO, CdO, BaO, and PbO) Containing Bismuth Borate Lithium Glasses

Bismuth based quaternary glasses with compositions BiBLM: 50Bi2O3–20B2O3–15Li2O–15MO (where MO = ZnO, CdO, BaO, and PbO) were processed by conventional melt quenching. The effectiveness of various modifier oxides on the optical and structural properties of the developed glasses was studied systematically by XRD, DSC, FTIR, Raman, and optical absorption (OA) measurements. The synthesized glass specimens were characterized by XRD and the patterns demonstrated an amorphous nature. The physical characteristics such as molar mass, density, and OPD values were found to increase with an increase in the molar mass of the modifier oxides, while there was a decrement in oxygen molar volume, thus resulting in decrement of complete molar volume of the prepared glasses. From DSC analysis, incorrigible reduction and enhancement of Tg and thermal stability among various modifier oxides in the glass network was noticed. Optical absorption data for glass specimens have confirmed the decrease in both direct and indirect optical band gap values among various modifier oxides incorporation. These investigations support the obtained Urbach energy (UE) and metallization criteria of synthesized glasses. The ionic characteristic for the glass specimens were confirmed by the values of electronic polarizability and electronegativity. The Raman and FT-IR spectra of the glass specimens displayed the existence of BiO3, BiO6, ZnO4, CdO4, BaO4, BO3, PbO4, and BO4 structural units within the glass matrix. These structural results can support the applications of as-developed glasses in the area of photonics.

A study on optical and thermal properties of natural polymer-based hemicellulose compounds

Films of husks of Plantango ovate, Cydonia oblonga, Mimosa pudica, Cochlospermum religiosum were prepared, delignified without protein and cellulose content, and their optical properties were evaluated. UV-Vis, FTIR TGA analysis revealed that these natural materials have strong potential in fiber optics, contact lenses and human transplantation infrastructure applications, where there is need of efficient transparency, high thermal stability and good conductivity with minimum light absorption. These natural polymeric films possess significant direct and indirect optical band gap values and better optical conductivity than currently in use synthetic polymeric materials. The Refractive index of these films is also found high in the visible region in comparison to pure or composite metal-doped synthetic films. Urbach energy (Eu), Dispersion energy (Ed), Average oscillation wavelength (λ0), and oscillation strength(S0) of this hemicellulose based natural polymeric films were found to be appropriate for such optical materials which are green, organic, economical and compatible to human systems.

Ta2O5-doped zinc-borate glasses: physical, structural, optical, thermal, and radiation shielding properties

In this study, examination of the physical, structural, optical and thermal properties of the glasses with the glass composition (100 − x)(0.6ZnO·0.4B2O3)·xTa2O5 (0, 1, 2, 3, 4 mol%) was aimed. Physical properties of the glasses synthesized with the classical melt-quenching method were calculated; density and molar volume values of the synthesized glasses based on the doping quantity were calculated. FTIR spectra were used in order to determine the structural properties in doped glasses. During the optical examinations of the synthesized glasses, direct and indirect optical band gap values were obtained with the help of Tauc plot method, and Urbach energies were calculated. Glass transition temperatures, melting temperatures, crystallization temperatures, and thermal stabilities were determined with DSC analysis. The main purpose of this study is to synthesize high-density glasses by adding higher-density Ta2O5 instead of relatively low-density chemicals (ZnO and B2O3) and to examine the radiation shielding properties of these glasses. Therefore, the effect of Ta2O5 doping on gamma and neutron radiation shielding properties was investigated using Geant 4 Monte Carlo toolkit. It was observed that Ta2O5 doping increased radiation shielding properties significantly. Especially, the increase in gamma radiation shielding properties was determined to be more compared to the increase in neutron radiation shielding properties.

Structural, morphological and opto-electrical properties of transparent conducting SnO2 thin films: Influence of Sb doping

ABSTRACT Pure and antimony doped tin oxide (Sb:SnO2) thin solid films were synthesised through a simple and low-cost nebulised spray pyrolysis (NSP) route. The influence of Sb doping on the different physical properties of these films was systematically investigated. The results of X-ray diffraction (XRD) study exhibited polycrystalline in nature of all films with tetragonal cassiterite structure of single phase SnO2. XRD analysis also revealed the reduction in crystallite size as well as the grain size observed in scanning electron microscopy (SEM) with Sb doping concentration. The average transmittance of all the films was greater than 73% at the visible wavelength region and the transparency was reduced by Sb inclusion. The direct optical band gap value was the lowest of 3.94 eV for pure SnO2 and enhanced by Sb doping level. The effects of Sb doping concentration on extinction coefficient, refractive index, dielectric constant, optical conductivity and optical density of the films were examined. Photoluminescence spectrum revealed a broad violet emission peak near 390 nm and Sb doping intensified the peak. Both the resistivity and sheet resistance were found to vary in the range of 1.61 × 10−3 Ω.cm to 3.92 × 10−4 Ω.cm and 32.73 Ω/□ to 134.41 Ω/□, respectively with the variation of Sb doping concentration. The highest mobility and carrier concentration were 54.74 cm2/Vs and 7.02 × 1021 cm−3 for undoped and 10% Sb doped films, respectively. However, the figure of merit was found to be maximum of 1.38 × 10−3 (Ω/cm2)−1 for 5% Sb doping concentration among the films.

Spectroscopic and structural studies, thermal characterization, optical proprieties and theoretical investigation of 2-aminobenzimidazolium tetrachlorocobaltate(II).

In this study we present the crystal structure, spectroscopic and thermal behavior, Hirshfeld surface analysis, and DFT calculations of a new organic-inorganic hybrid compound (C7H8N3)2[CoCl4]. This compound crystallizes in the centrosymmetric space group P1¯. Single-crystal X-ray diffraction analysis indicates that structure consists of a succession of mixed layers formed by organic cations and inorganic anions parallel to the (001) plane and propagate according to the c-axis. Layers further are assembled into a 3D supramolecular architecture through N-H…Cl hydrogen bonds and π…π interactions. The peak positions of the experimental PXRD pattern are in agreement with the simulated ones from the crystal structure, indicating phase purity of the title compound. The presence of the different functional groups and the nature of their vibrations were identified by ATR-FTIR and FT-Raman spectroscopies. The tetrahedral environment of Co2+ was confirmed by UV-visible spectroscopy, where the spectrum shows three weak absorption bands in the visible range due to d-d electronic transitions 4A2(F) → 4T2(F), 4A2(F) → 4T1(F) and 4A2(F) → 4T1(P) typical of Co(II) coordination compounds. The direct and indirect optical band gap values were determined by Tauc method. The optimized structure and calculated vibrational frequencies were obtained by density functional theory (DFT) using B3LYP functional. TGA and DSC coupled to mass spectrometry (MS) experiments under argon atmosphere in the temperature range (25-950 °C) were carried out in order to determine the thermal stability of the title compound.