Optical Energy Gap Research Articles

Optical Properties of PVA Silicon Carbide Nano Composites Films Synthesized Via Laser Ablation

Background: Enhancing the optical characteristics of nano-silicon carbide and polyvinyl alcohol films is thought to be crucial for obtaining the semiconductor with the lowest energy gap for applications in electrical devices, digital displays, and sensors.
 Materials and Methods: Poly vinyl alcohol and silicon carbide's optical properties were examined. A pulsed laser with a 532 nm wavelength is used to create these nanoparticles into widespread nanoparticles in two environments (water and vinyl alcohol). Polyvinyl alcohol nanocomposite was created by spin coating silicon carbide particles with the weight fractions 0.90%, 0.91%, 0.93%, and 0.95%. Fourier spectroscopy was used to locate the functional groups based. Techniques FESEM were used to analyze the surface composition and nanoparticle dispersion on the membrane-surface of the nanocomposite. using spectroscopy UV-Vis used to record the absorbance spectrum in the range of (200-800) nm for ultraviolet radiation.
 Results: The direct energy gap (5.585, 5.310, 5.480, 4.986, 4.800) eV and the indirect (5.006, 4.880, 4.916, 4.683, 4.490) eV and Urbach energy (2.38, 2.45, 2.94, 2.74, 3.67) eV were calculated.for the samples by ratio, as shown in Table No. 1.
 Conclusion: By investigating the optical characteristics of nanoparticles, such as their extinction and absorption coefficients, direct and indirect optical energy gaps, and Urbach energies .increase in extinction and absorption coefficients Urbach energy when adding nano carbide to polyvinyl alcohol, results show narrowing of the direct and indirect energy gaps. This suggests that the nanocomposite's optical characteristics have improved.

ZnO nanocomposites containing Cd are synthesized with high photodegradation potential for wastewater treatment

The zinc oxide (ZnO) nanoparticle on a two - electron oxygen reduction reaction is a particularly promising candidate for in-situ application. Herein, we prepared the Cd doped ZnO nanocomposites through a simple hydrothermal method. The X-ray diffraction (XRD) analysis has been carried out to confirm the structure and size of the nanomaterial. The optical absorption and energy gap of the prepared nanoparticles have been identified by UV–vis-NIR studies. Photoluminescence (PL) studies on the synthesized nanomaterials confirm the characteristic existence of blue and green emission bands. Fourier transform infrared (FTIR) spectroscopy has been studied on the ZnO nanoparticles to analyze the -OH and CO-O vibrations. The structural and surface morphology analysis was inferred by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) microanalysis. Cd doped ZnO nanocomposites are environmentally friendly and can be utilized to quickly remove contaminants from wastewater. The findings from the adsorption equilibrium fit the Brunauer-Emmett-Teller (BET) model very well, showing multi-layer adsorption. The photodegradation studies on Cd doped ZnO nanocomposites were carried out, which is an advanced oxidation process widely used for methylene blue removal. Therefore, the higher photocatalytic performance revealed that Cd doped ZnO nanocomposites could be a promising photocatalyst for environmental remediation applications.

Synthesis and characterization of novel thiosemicarbazide for nonlinear optical applications: combined experimental and theoretical study

(E)-4-(4-methoxyphenyl)-1-((E)-3(2nitrophenyl) allylidene) thiosemicarbazide was synthesised and screened for nonlinear optical properties. The novel compound has been characterized by infrared spectroscopy, 1H and 13C nuclear magnetic resonance. The experimental and theoretical optical gap energy is obtained using the Tauc method and density functional theory and has been estimated to be around 2.72 and 2.69 eV, respectively. The synthesized thiosemicarbazide exhibits efficiency hyper-Rayleigh scattering hyperpolarizability is calculated to be 6794.51 a.u. at the PBE0 functional. A direct relationship of the hyper-Rayleigh scattering hyperpolarizability with the optical band gap and between the hyper-Rayleigh scattering hyperpolarizability and electric field-induced second harmonic generation is found. The study showed the potential of the novel thiosemicarbazide as nonlinear optical candidates.

Morphological, optical and electrochemical properties of tin(II) 2,3-naphthalocyanine for organic electronic applications

Herein, tin(II) 2,3-naphthalocyanine (SnNC) organic dye was successfully thermally deposited onto different optical transparent substrates such as glass, quartz, ITO, and FTO. FE-SEM technique reveals that SnNC film shows a uniform and symmetrical spherical-shaped with an average diameter of ∼50 nm. Annealing up to 473 K for 4 h increases the crystallite size of SnNC thin film. SnNC thin film shows absorption bands centered at 858 nm, 313 nm, and 249 nm with two shoulders at 775 nm and 350 nm. We present the absorbance, specular transmittance, specular reflectance and fluorescence properties of SnNc deposited on the different transparent substrates. The oscillator strengths (f) and the electric dipole strength (q2) of SnNC thin film were estimated from the molar absorptivity () spectra. According to the Tauc model, two optical gap transitions were estimated as 1.03 eV and 3.48 eV. Annealing up to 473 K for 4 h slightly increases them to 1.15 eV and 3.59 eV, respectively. At excitation wavelength = 360 nm, two emission bands were observed at around 403 nm and 674 nm. Upon annealing at 373 K and 473 K, the real part of the refractive index of SnNC thin film decreases, which is correlated with a decrease in mass density. Electrochemical HOMO—LUMO band gaps of SnNC estimated from the cyclic voltammetry (CV) measurements () agree well with the observed optical energy gap estimated from the optical measurements. The wide range absorption, emission, good thermal stability, suitable optical band gap, and electrochemical properties, prove an effective example of organic dye suitable for organic electronic applications.

Enhancing the optical properties of [P(MMA-co-AN)/ZrO2]TF by doping fluorescein dye, TD-DFT/DMOl3 simulations and COVID-19 main protease docking

Poly methyl methacrylate-co-acrylonitrile [P(MMA-co-AN)]HB hybrid blend was first synthesized by precipitation polymerization and characterized by static light scattering. With a thickness of 200 ± 5 nm, the hybrid nanocomposite of [P(MMA-co-AN)/ZrO2]HNC thin films were fabricated by spin coating method. X-Ray diffraction studies showed a monoclinic cell structure with an average crystalline size of 180 nm for the fabricated films. An improvement in the optical properties were figured out when fluorescein dye was doped in the hybrid nanocomposite. Where the optical energy gap was decreased from 4.31 to 4.025 eV for fluorescein doped hybrid nanocomposite. While a possible energy transfer between ZrO2 and fluorescein was investigated in the laser photoluminescence spectra. DFT-CASTEP simulations were deployed to calculate the theoretical optical properties for the molecules under consideration. The structural and optical simulations of [P(MMA-co-AN)/ZrO2]HNC were found to match the experimental data. Molecular docking studies of [P(MMA-co-AN)/ZrO2]Iso against the main protease of novel corona virus COVID 19 (PDB code 6LU7 Hormone) showed an interesting interaction.

Green synthesis and characterization of magnesium oxide nanoparticles for gas sensor application

Green synthesis and characterization of magnesium oxide nanoparticles for gas sensor application

Study of the optical and spectral properties of Phosphor Tellurite Semiconducting Oxide Glasses

A systematic series of binary Phosphor tellurite glasses in the form [(90-X%)TeO2-(X%)V2O5] in mol%, where X = (10,20,25,30,35) have been successfully prepared in standard method (melt quenching), The effect of adding (V2O5) have been discussed. The X-Ray diffraction spectrum shows that the glass composite had no sharp peaks, The absence of abroad hump at (2θ=25-30o) indicates the presence of (L.R.O) long-range structural was disorder. The glass network structure was discussed through IR and Raman spectroscope and that showed the glass network is built of (TeO3 and TeO4) units. From the UV-visible spectrum, the edge of absorption the optical energy gap (Eopt) Urbach energy (Eo), and refractive index (n), have been determined. The results show that (Eopt) decreased with the increase of (V2O5) concentration, and Urbach energy (Eo) decreased with the increase of (V2O5) content, the refractive index (n) increased with the increase of (V2O5) concentration. The thermal parameters such as transition temperature (Tg), thermal stability (S), and thermodynamic fragility (F) are calculated by differential scanning calorimetry (DSC). Structural analysis of the glass system was identified by scanning electron microscopy (SEM).

Divalent transition metal complexes of nitrogen, oxygen and sulfur containing ligand: design, structural, spectral, pH-metric, theoretical molecular modeling, analytical and mechanism studies

In the present study, the 1-Nicotinoyl-4-phenyl thiosemicarbazide (H2NPT) multidentate nitrogen, oxygen and sulfur containing ligand is being synthesized in a simple single step reaction by condensing 1:1 molar ratio of ethanolic solutions of both phenyl isothiocyanate and nicotinoyl hydrazine. The prepared H2NPT and its complexes with Co2+, Ni2+ and Zn2+ and Cu2+ were characterized by pH-metric titrations, elemental analysis, FTIR, electronic spectra and thermogravimetric (TGA) analyses. The association constant of the ligand and the stability constants of its complexes were calculated by pH-metric measurements in 50% ethanol–water mixture. Also, DFT method was used to draw the geometry of all compounds and the parameters such as bond lengths, bond angles, dipole moment, Frontier orbitals (HOMO, LUMO), MEP and other energetic parameters (optical energy gap, softness, hardness, electronegativity) were evaluated. The prepared H2NPT reacted with Co2+, Ni2+ and Zn2+ and Cu2+ metal ions to form colored precipitates that were readily floated to the surface solution using oleic acid (HOL) surfactant with vigorous shaking of the flotation cell. The heavy metals' concentrations in the dissolved precipitates are determined by flame atomic absorption spectrometry (FAAS). The different parameters affecting the flotation process were thoroughly investigated, viz. pH of sample solution, concentration of ligand, metal ions and HOL, temperature and interfering ions. Nano-gram quantities of Cu2+, Co2+, Ni2+ and Zn2+in 1500-ml samples are quantitatively determined with 1-Nicotinoyl-4-phenyl thiosemicarbazide (H2NPT) at pH 3.0–6.5 for Cu2+ and at 7.0–7.5 for Co2+, Ni2+ and Zn2+. The concentrations of these heavy metals are increased 300-fold. Interferences, on the flotation process, from various foreign ions were avoided by adding excess H2NPT. The mode of chelation between H2NPT and the investigated metal ions is proposed to be through the S, N and/or O atoms of the ligand. The mechanism of flotation is proposed to be due to an electrostatic interaction between the HOL surfactant and the formed metal–ligand complexes through H-bond formation. The proposed multi-element flotation methodology has been utilized for the determination of the analytes in certified reference materials, alloys, synthetic mixtures and in water samples with a recovery % more than 90% and a relative standard deviation (RSD), as a precision < 2%.

Investigation of the effect of Mo+2 ion concentration on linear and non-linear optical properties of tungsten trioxide thin films for optoelectronic applications

To achieve the goal of creating a single-phase mixture of transition metal oxides with high electrical efficiency, our investigation focused on studying the linear and nonlinear optical properties of a mixture of transitional oxides that is electrophoretically colored. For finding the best ratios, we also investigated the impact of adding molybdenum ion to tungsten trioxide on the linear and non-linear optical properties of the samples made using the spray pyrolysis method on heated glass substrates. The as-deposited films were amorphous, as demonstrated by the X-ray diffraction (XRD). All of the samples were transferred to the polycrystalline and acquire a triclinic structure after the thermal annealing at 500 °C for 2 h. At room temperature, transmission and reflection measurements in the wavelength range of 300–2500 nm were utilized to evaluate the absorption coefficient. MoxW1-xO3 thin films' optical density, optical energy gap, skin depth, and Urbach's parameters were also estimated. Urbach's energy, EU, decreases from 0.355 to 0.154, eV as Mo-content rises, while Tauc's band gap energy, Eg, decreases from 2.76 to 2.56 eV. The films' static refractive indices dropped from 2.832 to 2.081 in the low-energy region and from 3.832 to 2.446 in the high-energy region. The dispersion energies and other variables were investigated using the Wemple–DiDomenico and Sellmeier models. In addition, various dispersion and nonlinear parameters were estimated and thoroughly discussed. It was observed that the improvement in the crystallinity of W1-xMoxO3 thin films led to a decrease in the values of the third-order nonlinear susceptibility (χ(3)), mainly affected by the constant refractive index, which decays with an increase in Mo concentration. Simultaneously, the conductivity of the films rises proportionally with the photon energy and Mo content, which is attributed to the concurrent increase in the dielectric constants. In this work, new approach for fabrication of quality thin film of MoxW1-xO3 was demonstrated. This is the reason for obtaining the best results, which made these films an effective contribution to many important applications. Furthermore, MoxW1-xO3 thin films perovskite has large nonlinear optical proper. These findings highlight the potential utility of these films in diverse critical optical applications, such as commercial lasers, ultra-fast signal processing in optical communication systems, sensors, environmental monitoring, medicine, manufacturing and materials processing, military applications, as well as scientific instrumentation.

Electrical, morphological, optical and mathematical simulations equations studies in CAZO, CZO, AZO and ZNO films

Purpose In this paper, it can be seen from AFM images of the as-deposited ZnO and CZO films, and the particle size and shape are not clear, while by increasing annealing temperature, they become distinguishable. By increasing temperature to 600°C, ZnO and CZO, CAZO and aluminum-doped zinc oxide (AZO) films particles became almost spherical. Due to high content of Cu in CZO target, and of Al in AZO target which was 5% weight ratio, doping plays a great role in the subject. Therefore, the annealing processing strongly affect the size and the shape of nanoparticles. Design/methodology/approach In this paper, the authors tried to study, in detail, nobel optical characterizations of ZnO films doped by transition metals in different annealing temperature. The authors found that the values of skin depth, optical density, electron–phonon interaction, steepness parameter, band tail width, direct and indirect carriers transitions and the dissipation factor, free carriers density and roughness of films affect the optical properties, especially the optical absorptions of ZnO films doped by transition metals. Also these properties were affected by annealing temperatures. The authors also found that topography characterizations strongly were affected by these parameters. Findings The CZO films have maximum value of coordination number ß, with considering NC = 4, Za = 2, Ne = 8. The CZO films annealed at 500 °C have maximum value of optical density. The as-deposited CAZO films have maximum value of steepness parameters in about of 0.13 eV. The as-deposited AZO films have maximum value of dispersion energy Ed in about of 5.75 eV. Optical gap and disordering energy plots of films can be fitted by linear relationships Eg = 0.49 + 0.2 EU and Eg = 0.52 + 0.5 EU, respectively. Originality/value With considering Nc = 4, Za = 2, Ne = 8 for ZnO films, coordination number ß has maximum value of 0.198. CZO nanocomposites films annealed at 500°C have maximum value of optical density. Different linear fitting of ln (α) for films were obtained as y = Ax + B where 5&lt;A &lt; 17 and 5&lt;B &lt; 12. As-deposited CAZO nanocomposites films have minimum value of electron phonon interaction in about of 4.91 eV. Optical gap and disordering energy plots can be fitted by linear relationships Eg = 0.49 + 0.2 EU and Eg = 0.52 + 0.5 EU for as-deposited films and films annealed at 500°C, respectively. Steepness parameters of as-deposited CAZO nanocomposites films have maximum value of 0.13 eV. Dispersion energy Ed for as-deposited AZO nanocomposites films has maximum value of 5.75 eV.

Impact of Crystallite Size on Structural, Optical and Magnetic Characteristics of La0.7Sr0.15Ca0.15MnO3 Nanocrystalline

Nanocrystalline La0.7Sr0.15Ca0.15MnO3 (LSCMO) manganites were prepared by the combustion process and heated to various annealing temperatures (TA) to get various sized crystallites. The X-ray diffraction (XRD) patterns provided evidence that a Rhombohedral structure with space group was formed. Additionally, an increase in the size of the crystallites was observed, from 15.64 to 36.78nm, as the temperature (TA) increased from 700℃ to 1300℃. The FESEM micrographs revealed that homogeneous with porosity. The FTIR spectra showed five absorption peaks. The Optical energy gap of LSCMO nanocrystalline is decreased from 3.51 to 3.28 eV as annealed temperature raised, reveals that the LSCMO nanoparticles are semiconductor in nature. Room temperature Raman spectra of LSCMO nanoparticles demonstrate a notable reliance on annealing temperature. When the Raman modes were analysed with respect to TA, it was observed that the Raman vibrational phonon mode below 200cm-1 (A1g) and four modes (Eg) in the range 200-800cm-1 displayed significant displacements and widening, which were associated with oxygen sublattice distortion. Considerable changes were observed in both the intensity and full width half maximum (FWHM) of the five Raman modes as the annealing temperature increased. Magnetic behaviour using M-H loop at room temperature were measured by the Vibrating sample magnetometer revealed that gradation of saturation magnetization as the function of annealing temperature. Hence there is a remarkable crystallite size effect on optical and magnetic properties of LSCMO nanocrystallites.

Boron sub-phthalocyanine chloride deposited on PA substrate towards flexible optoelectronic devices: Structural, optical, and electrical characterization

Flexible thin film photovoltaic devices have been a way of interest for researchers through the last decade. Creating suitable ultrathin films of any material is necessary for the realization of flexible systems. Therefore, the current study aims to study the impact of the thickness of the Boron sub-phthalocyanine chloride B(SubPc)Cl deposited on flexible Polyacetate (PA) as a polymer substrate. The structural properties of B(SubPc)Cl/PA with different thicknesses have been investigated using XRD and AFM. The investigated samples show an amorphous characterization with grain size slightly changed from 107 to 131 nm for thicknesses of 76 and 300 nm respectively, which is affected by the effect of the thickness. The optical transmission and absorption were studied in the spectral range of 300–2500 nm where the characteristic bands of a metallic phthalocyanine known as B and Q bands were observed in this range of the spectrum. The dispersion parameters, optical dielectric, SELF, and VELF for B(SubPc)Cl/PA were calculated and interpreted. Also, by using Tauc's extrapolation, the optical energy gap (Eg) was calculated. The Eg has values of 1.76 and 3.19 for a thickness of 76 nm which increased by increasing the film thickness. The nonlinear optical properties of B(SubPc)Cl/PA have been investigated, and the values obtained showed a high nonlinear optical response. The research outcomes candidate B(SubPc)Cl/PA for optoelectronics applications such as solar cells, sensors, and nonlinear optical devices.

Effects of Oxygen Flows and Annealing Temperatures on Optical, Electrical, and Structural Properties of Co-Sputtered In2O3-Ga2O3-Zn Thin Films

This study investigated the effects of oxygen (O2) flow rates and annealing temperatures on optical, electrical, and structural properties of indium–gallium–zinc oxide (IGZO) film on glass substrates fabricated by using a co-sputtering system with two radio-frequency (RF) (In2O3 and Ga2O3) and one direct current (DC) (Zn) magnetron. The average transmittance and optical energy gap increased significantly when the oxygen flow rate was increased from 1 sccm to 3 sccm. An increased O2 flow during co-sputtering IGZO films caused the crystallinity of the InGaZn7O10 phase to increase, yielding a smoother and more uniform granular structure. The carrier mobility rose and the carrier concentration decreased with increasing O2 flow. The results of X-ray photoelectron spectra (XPS) analyses explained the impacts of the O2 flow rates and annealing temperatures on optical and electrical properties of the co-sputtered IGZO films. The optimum process conditions of the co-sputtered In2O3-Ga2O3-Zn films were revealed as an O2 flow rate of 3 sccm and an annealing temperature at 300 °C, which showed the largest average transmittance of 82.48%, a larger optical bandgap of 3.21 eV, and a larger carrier mobility of 7.01 cm2 V−1s−1. XPS results at various annealing temperatures indicated that the co-sputtered IGZO films with an O2 flow rate of 3 sccm have more stable chemical compositions among different annealing temperatures.

Coexistence of synaptic behaviour and negative differential resistance at room temperature in the resistive switching device based on natural indigo molecules

The memory storage and processing capability of human brain is throwing excitement and challenges to create a low power consuming “brain-like functioning device” called neuromorphic device which is the basis of automation and robotics. We demonstrate a robust and highly efficient two-terminal device (Al/Indigo/Al) based on natural indigo molecules to emulate synaptic functionalities for use in neuromorphic applications. The indigo molecules are sourced from plants and are stable at room temperature. Molecules exhibit an optical energy gap of ∼ 1.9 eV evidenced by UV–vis spectroscopy. A detailed analysis of conduction mechanism is performed via dc-electrical characteristics. Consistent negative differential resistance (NDR) is observed, which we attribute to the deep trap states. The analysis shows that conduction is due to the trap-assisted Poole-Frenkel effec. The device maintains an extremely stable high-resistance state (HRS) and low resistance state (LRS) up to 9000 cycles of read – write - erase operation. Further, the essential characteristics such as paired pulse facilitation (PPF) and paired pulse depression (PPD) have been measured on the device. Potentiation (learning) and depression (forgetting) curves follow double exponential with more than 85% of the potentiation/depression occurring in the initial few pulses. Non-linearity (NL) calculations suggest that the device performance can be tuned by carefully choosing the pulse voltage and pulse width such that the nonlinearity factor is reduced. This work clearly indicates an easy approach for the fabrication of natural organic molecule-based artificial synapse that works efficiently at room temperature, as well as the method for selecting measurement parameters to obtain low-power consuming artificial synapse.

Influence of γ-irradiation on the structural and optical properties of PVA/rGO films reinforced with rGO for nuclear shielding applications.

The polyvinyl alcohol films reinforced with reduced graphene oxide (PVA/rGO) have been synthesized by the film casting method. Fourier-transform infrared spectroscopy (FTIR) was used to measure the spectra for PVA/rGO films before and after being exposed to various dosages of γ-irradiation. XRD “X-ray diffraction” has been used to evaluate the structure of PVA/rGO before and after γ-ray irradiation and showed the potential for some H-bonding to be broken along with the splitting of the major chain. When compared to the non-irradiated sample, the FT-IR spectra of the irradiated samples show clear variations in peak locations and intensities. The absorbance spectral behavior of PVA/rGO film before and after irradiation with γ-rays at different dosages demonstrates a sharp and intense absorption spectrum centered at 205 nm and abroad, as well as a weak absorption spectrum centered at 277 nm. The absorbance spectrum fitting (ASF), the first derivation of the absorption spectrum fitting (DASF), and Tauc's methods were studied to investigate the optical energy gap for the PVA/rGO films before and after γ-irradiation with varied gamma doses. Also, the linear refractive index (n) for γ-irradiated PVA/rGO films was estimated and shows an increase in the values as the γ-doses increased. Such results show the great potential of the PVA/rGO polymer film in photovoltaic, polymer science applications, and radiation shielding.

Extraction and studies of optoelectrical parameters of PVC/Zn0.9M0.1S (M: Co, Fe, Mn, V) films

To be used in optoelectronic applications, the nanocomposites films (doped PVC with Zn0.9M0.1S samples: M = Co, Fe, Mn, V) were prepared in this study. Casting and solid-state reaction procedures were employed to prepare PVC/CMC/Zn0.9M0.1S films. Rietveld refinement method and transmission electron microscope technique were used to investigate the structure and microstructure parameters of Zn0.9M0.1S (M: Co, Fe, Mn, V). X-ray diffraction, Fourier transform infrared and scanning electron microscope techniques were used to study the change in the structure, surface morphology and vibrational bands of PVC polymer upon doping with Zn0.9M0.1S. According to the findings, changing the type of the transition metals in Zn0.9M0.1S caused a change in the host polymer's optical characteristics. Depending on the kind of transition metals in Zn0.9M0.1S, the direct and indirect optical energy gaps of PVC/CMC/Zn0.9M0.1S are irregularly reduced. The direct/indirect optical band gaps of PVC dropped from (5.59, 5.22) eV to minimum values of (5.3, 4.27) eV as it was doped with ZnS. As Zn0.9M0.1S was incorporated into the PVC matrix, the linear and nonlinear optical parameters increased. The fluorescence intensity of pristine PVC is very weak, and it enhanced greatly as it doped with Zn0.9M0.1S. The dielectric constant (ε′), dielectric loss factor (ε″), ac conductivity (σac), the real (M′) and imaginary (M″) parts of the electric modulus changed nonmonotonically with the type of metal in Zn0.9M0.1S. Among all polymers, ′, ″ and σac revealed highest values for the PVC/Zn0.9Co0.1S and the lowest ones for PVC/Zn0.9V0.1S.

[formula omitted] Mössbauer, optical and structural properties with ligand field effects of borosilicate glass doped with iron oxide

Here, an investigation of borosilicate glass doped with iron oxide and prepared by classical melt-quenching method. The internal macrostructure, optical absorbance, ligand field parameters, and Mössbauer spectra were studied. The density increased with increasing SiO2 content, while Fourier-transform infrared (FTIR) analysis reported that BO4 and SiO4 content increase with a decrease in NBO content. Optical electronic transitions through wavelength (402–948 nm) confirmed the existence of Fe3+ state, while the Fe2+ is not observed in optical absorbance because of its inane electronic transition at 2222 nm. The electronic transitions at (402, 452, 513, 602, and 701 nm) are assigned to Fe3+ in tetrahedral coordination (FeO4), while the electronic transitions at (795 and 948 nm) are related to Fe3+ in octahedral coordination (FeO6). Astonishingly, the ligand field parameters of Fe ions were studied. The crystal field splitting exhibits increasing values, while Racah parameters exhibit decreasing values. Moreover, nephelauxetic parameters reflect the propensity of the bonding nature between the Fe cations and their ligands towards a higher covalent nature with SiO2 additives. Further, a scant decrease in the optical band gap was explained based on the mixed former effect. Moreover, non-linear refractive indices augment with SiO2 addition. The decrease in the optical gap energy justified such a trend. Bewitchingly, Mössbauer spectra reported the existence ofFe3+ ions with isomer shift (0.285–0.314) mm s−1 in tetrahedral sites, while Fe3+ ions with isomer shift (0.339–0.425) mm s−1 in octahedral sites, agreeing with optical data. Surprisingly, Fe2+ ions with isomer shift at about 0.905 mm s−1 in tetrahedral sites was observed. The observed decrease in isomer shift of all phases is due to the decrease in electronegativity of formers. Furthermore, the decrease in quadrable splitting is attributed to the decline in the polarization power of the glass former cations with SiO2 addition.

Effect of Ni-concentration on the linear and nonlinear optical properties of MoS2 nanostructures

Ni-doped molybdenum disulfide (MoS[Formula: see text] powders at 1%, 2%, 3%, 4%, 5% and 7% of Ni are prepared by the hydrothermal method. Sophisticated analytical studies such as X-ray diffraction, Raman, TEM and photoluminescence (PL) were analyzed to predict their structural, morphological and optical properties. Effects of Ni-doping with MoS2 on crystalline structure, morphology as well their optical phenomenon were examined in detail. Ni doping on MoS2 revealed tetragonal crystal structure of the parent compound. A significant decrease in their optical energy gap (from 1.86 to 1.76[Formula: see text]eV) was perceived with Ni doping concentration increment. PL intensity exhibited a considerable improvement with Ni-doped MoS2 samples at room temperature. From a theoretical viewpoint, the compact density matrix method is applied for Ni–MoS2 to calculate their linear and nonlinear absorption coefficients as well as refractive index modulations for undoped and Ni-doped samples at the focal points of their corresponding intra-band and inter-band transitions. Observed findings are well correlated with the practical results which prove that Ni–MoS2 layers are promoters for potential applications in optoelectronic technology.

A DFT theoretical and experimental study of the effect of indium doping within electrochemical deposited ZnO

The effect of indium doping within ZnO-NRs nanorods on FTO substrates was studied using integrated theory and experiments. The electrochemical deposited In-ZnO NRs were examined by X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV–vis spectrophotometer, electrochemical cell, and Photocurrent spectroscopy. The obtained electronic and optical characteristics of the developed ZnO and In-ZnO films were validated by density functional theory (DFT) calculations using the TB-mBJ and PBE-GGA approximations. XRD patterns demonstrate that all electrodeposited films were crystalline having a hexagonal wurtzite with a preferred growth orientation (002). Furthermore, the crystallite particle size and (002) diffraction peak intensity of the samples reduces with In doping, suggesting a reduction in crystallinity with increasing indium. SEM images reveal a nicely defined hexagonal shape morphology of pure and In-doped ZnO nanorods, with an approximate mean diameter of ∼100 nm. UV spectrophotometry experiments and DFT calculations showed that the inclusion of In leads to a minor reduction in the optical gap energy. Mott-Schottky analysis displays an improvement in the conductivity attributed to an enhanced electronic injection in In-ZnO the conduction band, thus enhancing the photoelectrochemical properties of the zinc oxide film.

Synthesis of CuO@TiO2 nanocomposite and its photocatalytic and electrochemical properties. Application for treatment of azo dyes in industrial wastewater

In the present study, the photocatalytic characteristics of CuO@TiO2 nanocomposite for the decolorization of Acid Yellow 36 (AY36) are investigated. FE-SEM, XRD, EDS, and XPS structural studies of nanostructured photocatalysts showed that the CuO and TiO2 in the CuO@TiO2 (3:5) nanocomposite were successfully incorporated and formed the heterostructure. Results of optical investigations showed the optical gap energies of pure CuO, TiO2, CuO@TiO2 (1:5), CuO@TiO2 (3:5), CuO@TiO2 (5:5), and CuO@TiO2 (6:5) nanocomposite were 1.88, 3.05, 2.94, 2.81, 2.77, and 2.71 eV, respectively. According to the findings, the CuO@TiO2 nanocomposite is a potential candidate for visible light-consumed photocatalyst. Electrochemical analyses exhibited that charge transfer resistance was significantly reduced in CuO@TiO2 nanocomposite samples, indicating an effective separation of photo-excited electron-hole pairs. Photocatalytic studies reflected the fast photocatalytic degradation rate in the presence of CuO@TiO2 nanocomposites compared to pure CuO and TiO2. The results showed that 20, 30, 50, 100, and 200 mg/L of AY36 were completely eliminated after 35, 45, 65, 110, and 185 min of exposure to simulated sunlight, respectively. A CuO@TiO2 nanocomposite was effectively used to photocatalytically decolorize AY36 from actual textile wastewater after the photocatalytic performance of the material was investigated for AY36 decolorization from deionized water and industrial wastewater.