Decrease In Band Gap Research Articles

Nanoarchitectonics of MIL-101(Fe)/g-C3N4 S-Scheme heterojunction for photocatalytic nitrogen fixation: Mechanisms and performance

Recently, there has been a growing interest in the fundamental understanding of the mechanism of how MIL-101(Fe)/g-C3N4 heterojunctions facilitate the occurrence of photocatalytic nitrogen fixation reactions, especially the electron transfer mechanism has attained increasing attention in photocatalysis. Herein, we implemented a "triple win scenario" strategy to fabricate the S-scheme MIL-101(Fe)/g-C3N4 heterojunction through a straightforward solvothermal process. The MC-6 heterojunction minimizes the recombination of photogenerated carriers, enhances light utilization efficiency, and activates the N≡N bond, thus boosting photocatalytic nitrogen fixation efficiency. The transition metal iron activates the N≡N bond, while S-scheme heterojunctions reduce the photogenerated carrier recombination. In addition, the decrease in band gap (Eg) leads to an increase in visible light utilization efficiency. ISIXPS proved the mechanism of interelectron transfer of MIL-101(Fe)/g-C3N4 heterojunction under illumination. Upon the creation of the heterojunction, electrons migrate from g-C3N4 to MIL-101(Fe), establishing an inherent electric field due to the disparate Fermi levels between the two materials. The electrons (e-) on the g-C3N4 CB with a more negative reduction potential and the holes (h+) on the MIL-101(Fe) VB are retained, which increased the redox capacity to a great extent required for the reduction of N2 to NH3. The ammonia production efficiency of MC-6 photocatalyst was 160 µmol gcat-1 h-1, representing an 8-fold and 2.8-fold improvement over pristine g-C3N4 (20 µmol gcat-1 h-1) and MIL-101(Fe) (57 µmol gcat-1 h-1), respectively.

3D Lead-Organoselenide-Halide Perovskites and their Mixed-Chalcogenide and Mixed-Halide Alloys.

We incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se-), which occupies both the X- and A+ sites in the prototypical ABX3 perovskite. The new organoselenide-halide perovskites: (SeCYS)PbX2 (X=Cl, Br) expand upon the recently discovered organosulfide-halide perovskites. Single-crystal X-ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide-halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid-state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable band gap decrease. Optical absorbance measurements indeed show band gaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X=Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the band gap from 1.86 to 2.31 eV-straddling the ideal range for tandem solar cells or visible-light photocatalysis. The comprehensive description of the average and local structures, and how they can fine-tune the band gap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid-state and organo-main-group chemistry.

3D Lead‐Organoselenide‐Halide Perovskites and their Mixed‐Chalcogenide and Mixed‐Halide Alloys

AbstractWe incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se−), which occupies both the X− and A+ sites in the prototypical ABX3 perovskite. The new organoselenide‐halide perovskites: (SeCYS)PbX2 (X=Cl, Br) expand upon the recently discovered organosulfide‐halide perovskites. Single‐crystal X‐ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide‐halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid‐state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable band gap decrease. Optical absorbance measurements indeed show band gaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X=Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the band gap from 1.86 to 2.31 eV–straddling the ideal range for tandem solar cells or visible‐light photocatalysis. The comprehensive description of the average and local structures, and how they can fine‐tune the band gap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid‐state and organo‐main‐group chemistry.

On the response of the CR-39 NTD to low doses of gamma rays using optical and photoluminescence spectroscopy

In this work, the response of the CR-39 nuclear track detector (NTD) exposed to different low doses of gamma rays was investigated using UV–Vis and photoluminescence spectroscopy. Five NTDs of CR-39 were irradiated with low gamma-ray doses ranging from 10 to 120 kGy using a60Co source. The dose of gamma rays correlates with red shift in the absorption spectra of a gamma-irradiated CR-39 detector. As the gamma dose increases, the indirect and direct energy band gaps, as well as Urbach energy, decrease gradually. However, the decrease in the indirect optical band gap is greater than the decrease in the direct band gap. The observed spectra of the CR-39 detector after being irradiated with different doses of γ-rays showed an acceptable variation in photoluminescence (PL) emission spectra generated by a well-defined excitation wavelength of 290 nm. Starting at 45 kGy dose, the integrated area of the photoluminescence peak increases and tends to saturate, whereas the photoluminescence peak height is linearly correlated with the gamma dose with high sensitivity, which is 53.1 ± 6.3 CPS. kGy−1. According to the current findings, photoluminescence (PL) spectroscopy has a greater sensitivity than UV–Vis spectroscopy for measuring the response of the CR-39 detector to gamma rays in the dose range of 10–120 kGy. The results reflected a potential possibility of using the CR-39 detector in dosimetric applications of low gamma ray doses through the high resolution achieved by photoluminescence (PL) and UV–Vis spectroscopy.

Improved electrochemical performance of Fe3O4/TiO2 composite thin film electrode for energy storage applications

This study is the first attempt to examine the electrochemical properties of TiO2 composite with Fe3O4 thin film. In our analysis, X-Ray diffraction (XRD) confirms the formation of Fe3O4 on TiO2. Fourier Transform Infrared Spectroscopy (FT-IR) and Raman spectroscopy confirmed the functional groups. The UV–Vis spectroscopy analysis shows that the addition of Fe3O4 results in decrease in optical band gap. Our Cyclic Voltammetry (CV) results demonstrate that, under steady state conditions, the behaviors of TiO2 and Fe3O4/TiO2 electrodes regarding ion adsorption and charge transmission vary. Pseudocapacitive effects and charge transfer affects the functionality of the TiO2 electrode, whereas two-layer capacitance effects primarily control the response of the Fe3O4/TiO2 electrode. Numerous factors, including ion diffusion, rate capability, charge transfer, and series resistance, can be directly determined using electrochemical impedance spectroscopy (EIS). The experimental results and analysis presented in this work brings to light the significance of Fe3O4 in the electrochemical response of an electrode-electrolyte interface.

Influence of Ni2+ on OER kinetics and photoluminescence properties of ZnSnO3 nanoparticles

Ni2+ doped ZnSnO3 nanoparticles (NPs) were synthesized using Aloe vera mediated solution combustion method, followed by an investigation into their luminescence and oxygen evolution reaction properties. The Bragg reflections of ZnSnO3: Ni(1–9 mol%) NPs revealed a cubic structure, with the addition of the dopant inducing lattice strain and resulting in peak shifting towards higher angles. No impurity-related peaks were observed. The estimated crystallite size and optical band gap decrease (3.1–2.94 eV) with an increase in dopant concentration. The surface morphology consists of irregular-sized and shaped NPs with hallows. The EDAX spectra show the purity of the sample. Photoluminescence emission spectra were recorded at a 230 nm excitation wavelength, where intense blue emission observed at 482 nm was attributed to a direct transition between the conduction band edge and the valence band edge, corresponding to the direct recombination of free excitons. Another satellite peak observed at 525 nm can be attributed to oxygen deficiency. Moreover, the nanoparticles exhibited outstanding performance in oxygen evolution reaction studies, showing low over potentials between 300 and 318 mV, a minimal Tafel slope of range 63–72 mV dec−1, and stable electrochemical behavior over 12 h at a current density of 23 mA/cm2. These results highlight their effectiveness as electrocatalysts.

Electronic and adsorption properties of halogen molecule X2 (X=F, Cl) adsorbed arsenene: First-principles study

The geometry, electronic structure, and adsorption properties of halogen molecule X2(X = F, Cl) on arsenene were investigated using first-principles calculations. The adsorption of molecules was considered at various sites and in various orientations on the pristine arsenene (p-As) surface. Both molecules show chemisorption and the crystal orbital Hamiltonian population (COHP) analysis reveals the formation of strong X-As bonds. In particular, the adsorbed molecules spontaneously dissociate into atomic halogen atoms, with a diffusion barrier of 1.91 (1.72) eV for F2(Cl2). The adsorbed X2 molecules induced distortions in the local geometry due to strong interaction with arsenene. Importantly, the formation of X-As bonding remarkably changed the electronic properties, evidenced by the decrease of the actual band gap due to the emergence of defect states within the band gap. For instance, the F2 adsorbed arsenene system (F2-As) exhibited an average band gap of 1.17 eV, and Cl2 adsorbed arsenene (Cl2-As) showed an average band gap of 0.83 eV. In particular, indirect to direct band gap transition was observed for some adsorption configurations. The reduction in band gap resulted in the enhancement of electrical conductivity. These findings suggest that the electronic properties of arsenene can be tuned by halogen decoration.

Crystallization, structural, and optical properties of the 2BaF2·Al2O3·B2O3 glass in the presence of Er2O3 and SiO2

This study investigates the crystallization behavior and optical properties of the 2BaF2·Al2O3·B2O3 oxyfluoride glass in the presence of SiO2 and Er2O3 compositions. Samples were synthesized using the melt-quenching method. The amorphous nature of the prepared samples was characterized through X-ray diffraction (XRD) analysis. Differential thermal analysis (DTA) was subsequently employed to determine the glass transition temperature (Tg) and crystallization temperature (Tc). The presence of SiO2 and Er2O3 was found to enhance the glass forming ability and the crystallization temperature of the system. The optical bandgap was calculated by drawing Tauc plots from UV–Vis spectra. Notably, the presence of SiO2 caused a red-shift in the UV-absorbance edge of the glass, and resulting in a decrease in the optical bandgap. Molecular structure was further studied by Raman and FTIR analysis. Based on the DTA curves, glasses were heat-treated and the resulting glass-ceramics were analyzed using XRD, Photoluminescence and field emission scanning electron microscopy (FESEM). XRD analysis confirmed the crystallization of the BaAlBO3F2 crystalline phase within the glass matrix. Furthermore, the recorded down-shifted and upconversion photoluminescence spectra indicated that the Er3+ doped glass-ceramics have stronger emissions compared to glasses.

Innovative Type-II ZnSe/InSSe heterojunction: Photocatalytic properties and strain modulation from first-principles calculations

In this study, we propose an innovative type-II ZnSe/InSSe heterojunction for efficient photocatalytic water-splitting. This heterojunction exhibits a direct band gap of 1.9 eV and staggered band alignment, which efficiently separates photogenerated carriers, facilitating overall water-splitting. The built-in electric field drives electrons to accumulate in the InSSe layer and holes accumulate in the ZnSe layer, thereby suppressing recombination and enhancing photocatalytic efficiency. The solar-to-hydrogen efficiency reaches 8.92 %. Furthermore, the electronic and optical properties of ZnSe/InSSe heterojunction can be modified by biaxial strain, with tensile strain significantly improving visible light absorption and overall efficiency. Under tensile strain, the band gap decreases, enhancing the light absorption capability in the visible range, which further boosts the photocatalytic performance. Our findings demonstrate the ZnSe/InSSe heterojunction as a promising candidate for high-efficiency photocatalytic hydrogen production, offering valuable insights for future photocatalyst development. This research provides a potential pathway to optimize semiconductor heterojunctions for sustainable energy applications through strain engineering.

Impact of metal doping and non metal loading on the photocatalytic degradation of organic pollutants using tin dioxide catalyst under sunlight irradiation

The goal of this study is to prepare nickel (Ni) doped tin dioxide-loaded activated carbon composite as a catalyst for the removal of dye. Tin dioxide with various (0.050, 0.075, and 0.10 M) Ni doping concentrations and Ni: SnO2/CCAC (corn cob activated carbon) composite was synthesized by the chemical precipitation method and labeled as NS1, NS2, NS3, and NS3/CCAC. XRD spectra revealed that the particle size in NS3/CCAC decreased (12.81 nm) as the NS3 and CCAC content. The absorption spectra reveal that the band gap in NS3/CCAC was reduced (3.50 eV) by the Ni-doping and CCAC-loading. We also used photodegradation of methylene blue (MB) in the presence of sunshine to examine the photocatalytic performance of the NS3/CCAC composite. The NS3/CCAC composite exhibited higher photocatalytic efficiency in comparison to the other samples. The high photodegradation performance (92.30 %) of the composite sample was due to its less average crystallite size, which increased the specific surface area (306.01 m2/g), decreased band gap, and reduced the electron–hole recombination rate resulting in improved photocatalytic efficiency. The findings reported here could benefit the NS3/CCAC photocatalysts for the removal of organic pollutants.

Tailoring monoclinic Na3V2(PO4)3-based cathode via bimetallic substitution for high-energy and long-lifespan Na-ion batteries

Na3V2(PO4)3 is a promising cathode for Na-ion batteries (NIBs) owing to the high electrochemical reversibility. The Na3V2(PO4)3 has two typical polymorphs including rhombohedral and monoclinic phases; the former has been extensively studied, whereas the latter is rarely reported. Here, we successfully designed monoclinic Na3V2(PO4)-based cathode via Ga and Fe substitutions owing to the lowered lattice energy. In addition, we revealed that Ga substitution improves average voltage owing to the activation of the V4+/V5+ redox couple and the Fe substitution enhances rate capability due to the decreased band gap and Na-ion diffusion activation energy. As a result, the designed monoclinic Na3V1.6Ga0.2Fe0.2(PO4)3 cathode exhibits high voltage plateaus (3.4 V and 4 V) and high-rate capability (from 116.8 mA h/g at 0.2 C to 103 mA h/g at 20 C) as well as superior cycling stability (99.9% capacity retention over 4,500 cycles at 5 C). Moreover, the assembled Na3V1.6Ga0.2Fe0.2(PO4)3//hard carbon full cell delivers a high-energy density of 313.8 Wh/kg with 86.4% capacity retention after 100 cycles at 1 C. This work demonstrates the design of monoclinic Na3V2(PO4)3-based cathode via bimetallic substitution, providing a new route for development of high-energy and long-lifespan NIBs.

Design and characterization of borosilicate glass modified with TiO2 for enhanced optical and radiation shielding applications

This work investigates the potential of borosilicate glass doped with titanium dioxide (TiO2) for radiation shielding applications. The study explored the impact of varying TiO2 concentrations on the glass structure, optical properties, and radiation shielding effectiveness. X-ray diffraction (XRD) and Raman spectroscopy confirmed the amorphous nature of the glasses. The addition of TiO2 affected the glass network structure, as evidenced by changes in the Raman spectra and density measurements. UV–Vis spectroscopy revealed a red shift in the absorption edge (416–481 nm) and a decrease in the indirect optical band gap (2.91–2.70 eV) with increasing TiO2 content. The refractive index also increased from 2.54 to 3.54 with TiO2 concentration. The mass attenuation coefficient (MAC) and linear attenuation coefficient (LAC) increased significantly with TiO2 addition, indicating enhanced radiation attenuation capability. The inclusion of TiO2 reduced the half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP), while increasing the effective atomic number (Zeff). The effective electron density (Neff) and effective conductivity (Ceff) showed a slight increase with TiO2 content. Energy build-up factors (EBF and EABF) indicated a higher rate of radiation intensity increase and energy absorption within the glass due to the presence of TiO2. Finally, the incorporation of TiO2 into borosilicate glass offered a promising approach to developing improved optical and radiation shielding glasses.

Green synthesis of calcium nanoferrites using leaf extract of Brassica oleracea for photocatalysis of malachite green dye

The calcium ferrite nanoparticles were made by the sol–gel process. X-ray diffraction, a scanning electron microscope, and UV–vis spectroscopy were used to analyze the material. There is an orthorhombic phase in the space group Pnma. There were four techniques used to calculate the average crystallite size. Using ImageJ software, the particles were aggregated and their size was ascertained. Using energy-dispersive X-ray (EDX) analysis, the composition of the material was ascertained. 2.29 eV was determined to be the band gap. Vibrating test magnetometer (VSM) provided an explanation for the materials’ magnetic property. A decreased band gap energy is responsible for the 90% degradation of malachite green dye at a concentration of 15 mg/L in 150 min, with a four-cycle reusability.

Structural, optical, and morphological properties of PVC-BaTiO3 nanocomposite films

This work aims to fabricate barium titanate (BaTiO3) nanoparticles and study the effect of adding different contents of BaTiO3 nanoparticles on the structural, optical, and electrical properties of PVC polymer matrices. The PVC/BaTiO3 nanocomposite films were characterized by X-ray diffraction, FT-IR spectroscopy, and SEM. In addition, dielectric properties were studied within the frequency range of 0.1 KHz–6 MHZ. The XRD analysis reveals an amorphous nature of pure PVC with two characteristic peaks at 2θ = 17.09° and 2θ = 23.25°, and it reveals that BaTiO3 has sharp and narrow peaks. In PVC/BaTiO3 nanocomposite films, all XRD peaks of BaTiO3 appeared in all the samples with an increase in the average particle size from ∼46 nm to 55 nm. There is no shift of IR position in PVC bands, but the decreased intensity of some bands suggests complexation between PVC and BaTiO3. The UV–visible absorption spectrum of pure PVC has a band at λ = 278 nm. This band was shifted to 252 nm after adding BaTiO3 content. UV–visible transmission spectra demonstrate a decrease in the transmittance as an increase of BaTiO3 content from 89.23 % for pure PVC to 5.23 % for 0.1 wt% of BaTiO3. The values of the optical bandgap decrease with increasing BaTiO3 contents due to defect formation in PVC matrices. The optical parameters of the prepared nanocomposite films were also enhanced. The AC conductivity shows an increase with both frequency and BaTiO3 concentration, leading to enhanced movement of charge carriers and relaxation of interface polarization.

Investigating the role of Ag-doped ZnO thin films in UV photodetectors produced via laser assisted chemical bath growth technique

This study introduces the innovative fabrication of Ag-doped ZnO thin films (AgxZnO(100−x) TFs) with varying silver (Ag) concentrations (x) of 0.5, 1.0, 1.5, and 2.0 at% on glass substrates using a simple and cost-effective method known as laser-assisted chemical bath growth (LACBG). This process aims to create metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors. A continuous wave semiconductor laser with a 444.5 nm wavelength, 5 W power, and 6 min irradiation time was employed to synthesize high-quality Ag-doped ZnO TFs on the glass substrate. Ag electrodes were utilized as Schottky contacts to form MSM UV photodetectors. Structural and morphological analyses conducted using XRD and SEM revealed vertically aligned nanorods and nanoflowers with a high c-axis orientation and hexagonal wurtzite facets, while EDX confirmed Ag incorporation into the ZnO lattice. The UV–Visible absorbance spectra indicated a decrease in bandgap from 3.28 to 2.84 eV with increased Ag content. The current-voltage (I–V) characteristics of the Ag-doped ZnO TFs UV photodetector showed significantly enhanced conductivity at a 2.0 at% concentration level, achieving a responsivity of 10.78 A/W, an external quantum efficiency of 34.67 % at −3 V bias voltage. Finally, the modified device exhibited a sensitivity of 14661.9 %, a gain of 147.62, and a detectivity of 2.25 ×107 Jones, demonstrating its suitability for optoelectronic applications.

Cerium oxide-reinforced Fe2O3–Na2O–SiO2–B2O3 glass matrix for protection against ionizing X and gamma rays

Radiation shielding glass is an interesting material in the field of radiation shielding due to its remarkable features. In the present paper, we investigated the physical properties of radiation-shielding glass materials that consist of sodium oxide (Na2O), cerium oxide (CeO2), and iron oxide (Fe2O3) incorporated into borosilicate glasses with the formula 90SiO2-(70-x)B2O3+ 20Na2O–1Fe2O3-xCeO2 (CeFeNaBS-glasses). One of the distinguishing characteristics of this glass system is its enhanced radiation shielding capabilities. The structural studies indicated a gradual rise in glass density from 1.954 to 2.658 g/cm with further CeO2 doping. Optical studies showed that the optical band gaps went down from 3.41 eV to 3.33 eV as the amount of CeO2 in the CeFeNaBS-glass matrix rose. The decrease in optical band gap has been correlated with the rising basicity. Also, the increased basicity behavior induces more conversion of Ce3+ to Ce4+ ions by losing a 4f electron. Moreover, with further CeO2 additions, the glass color changed from light brown to dark brown. The presence of Ce4+ ions with further CeO2 additions is responsible for this color transformation. The linear and non-linear refractive indices exhibit enhanced behaviors with higher CeO2 concentrations. We used declining basicity and polarizability behaviors to describe this behavior. The incorporation of larger CeO2 concentrations enhances the ability to improve radiation shielding properties, as demonstrated by the increased values of the mass attenuation coefficient and half-value layer, especially in the energy ranges of soft tissues X-ray and hard tissues X-ray. Hence, the investigated CeFeNaBS-glasses exhibit enhanced transparency and radiation shielding capabilities, rendering them highly suitable for implementation in this domain.

Construction of scheelite CaWO4 with natural diatomite for boosted photocatalytic degradation of tetracycline and doxycycline antibiotics under natural conditions

Fabrication of efficient and recyclable catalysts with natural supporting materials is still a challenge in the field of photocatalysis. In the present work, scheelite type calcium tungstate was successfully constructed with natural diatomite via in-situ co-precipitation method for effective photocatalytic degradation of tetracycline (TC) and doxycycline (DC) antibiotics. The as-synthesized photocatalysts were characterized by SEM-EDX, TEM, BET, XRD, XRF, XPS, FTIR, UV–vis DRS, PL and EIS techniques. The morphological and physiochemical analyses confirmed the successful hybridization of CaWO4 with natural diatomite. The optical, photoluminescence and electrochemical tests confirmed that the composite material displayed narrower band gap energy, lower recombination rate and facilitated separation of photogenerated carriers. After construction of CaWO4 with the diatomite structure, the TC and DC decomposition efficiencies were found 4.70 and 2.54 times higher than that of the pristine sample, respectively. Furthermore, the composite catalyst showed superior degradation performances (91.8 % for TC and 90.7 % for DC) in the presence of hydrogen peroxide as a Fenton-agent. The enhanced photocatalytic performance was assigned to the increased specific surface area and pore volume, decreased band gap energy, limited recombination rate of photoinduced carriers, decreased charge transfer resistance as well as the abundant of hydroxyl radicals. The degradation reaction was found to be mainly driven by photogenerated holes and superoxide radicals. The CWO@DT/Vis/Fenton catalytic system exhibited good performance at near-neutral pH, also the composite catalyst was sufficiently utilized in the presence of co-existing anions. Furthermore, the photocatalytic efficiency was also tested under natural sunlight irradiation and the TC degradation remained 71.4 % after four cycles, indicating the outstanding feature of the composite catalyst in outdoor process conditions. Under these circumstances, the present work demonstrated the utilization potential of natural diatomite for effective photocatalytic remediation of antibiotic molecules under natural sunlight irradiation.

(Ce, Nd) co-doped TiO2 NPs via hydrothermal route:Structural, optical, photocatalytic and thermal behavior

Rare earth (Ce, Nd) doped/co-doped titania (TiO2) nanoparticles were successfully produced by hydrothermal route. Titanium isopropoxide (IV), cerium nitrate hexahydrate and neodymium nitrate hexahydrate were utilized as raw/starting materials. The effect of Ce and Nd doping/co-doping in TiO2 were studied through different complementary tools such as XRD, FTIR, FE-SEM, EDX, XPS, UV–Visible, PL, photocatalytic and thermal analysis. XRD spectra revealed anatase tetragonal phase and cubic phase due to titania and ceria nanoparticles respectively. The crystallite size, lattice constants, volume and no. of unit cell were determined through XRD data. Optical studies revealed the band gap, urbach energy, extinction coefficient, refractive index, optical conductivity and photoluminescence emission wavelength. FTIR spectra investigated the chemical bondings and functional groups present in prepared samples. Optical absorption spectra confirmed that absorption edge is red shifted, indicating a decrease in band gap from 3.5 to 3.0 eV with the incorporation of rare earth ions (Ce, Nd) in TiO2 matrix. The rate of electron-hole pair recombination was reduced through co-doping of (Ce, Nd) in TiO2 lattice as exhibited by reduction in intensity of photo luminescence spectra. The photocatalytic efficiency was enhanced with the integration of rare earth metal ions in TiO2 matrix for different dyes such as rhodamine B (RhB) and malachite green (MG) with visible light irradiation. The degradation efficiency of (Ce, Nd) co-doped TiO2 NPs against RhB and MG dyes was found to be 89 and 95 % respectively. TGA analysis was carried out to find weight loss during different thermodynamic phases such as dehydration, decomposition and combustion, and crystallization. Various thermodynamic parameters such as activation energy, entropy and enthalpy were estimated by thermal analysis.

Anodization of cast and sintered Fe40Al alloy in etidronic acid: Morphological and semiconductive properties of the oxide films

Fe40Al alloys produced by casting and sintering were anodized to form nanostructured oxide layers. Microstructural characterization revealed a lower grain size for the sintered alloy compared to the cast alloy. Anodizing was performed in four electrolytes with a constant etidronic acid concentration (0.3 M) and different ethylene glycol-water ratios. Different voltages (5–400 V) and treatment times (1–4 hours) were evaluated for cast and sintered Fe40Al alloys. Among the studied anodization regimes, only four anodic films formed on sintered Fe40Al were homogeneous. These films were annealed at 900°C and analyzed by conventional characterization techniques (SEM/EDS and XRD). Results indicated a non-self-ordered morphology and different content of P, Fe, and Al species as a function of the electrolyte composition. Annealing post-treatment led to the formation of Fe/Al oxides and spinels in selected anodic films. An additional peak of FePO4 was detected only in the anodic film formed in pure ethylene glycol. The band gap values (UV-Vis reflectance spectroscopy) of the anodic film formed in ethylene glycol decreased from 2.87 eV to 2.45 eV after annealing. This band gap decrease was associated with the preferential formation of conductive phases (Fe2O3 and FeAlO3) over insulating phases (γ-Al2O3 and FeAl2O4) after annealing.

Synthesis and Characterization of Polycarbonate/Polystyren/Polyethylene Oxide/Zinc Sulfide Nanocomposites: Gamma Ray Induced Changes in their Optical and Color Properties

Amorphous polycarbonate (PC), amorphous polystyrene (PS), semicrystalline polyethylene oxide (PEO) and zinc sulfide (ZnS) nanoparticles (NP) were used to fabricate PC/PS/PEO/ZnS nanocomposite (NC) films. We believe that this study is novel in the area of the effect of γ ray radiation on such NC. The synthesized ZnS NP had an average particle size of 18 nm, as indicated from the Rietveld refinement of the X-ray diffraction (XRD) scans. Samples of the PC/PS/PEO/ZnS NC films were irradiated with γ ray doses ranging from 20 to 180 kGy. UV-vis spectroscopy and the International Commission on Illumination (CIE) color changes technique were used to investigate the resulting effects of the γ ray irradiation on the optical and color properties of the prepared films. The light absorbance of the NC films increased as it was irradiated with the γ ray doses up to 180 kGy, the maximum dose used. The increase in absorbance was associated with a decrease in the direct bandgap from 5.88 to 4.92 eV, and an increase of Urbach energy from 0.43 to 0.81 eV. This was attributed to the dominance of chain crosslinks. The γ ray effects on the absorbance, extinction coefficient, refractive index and optical conductivity of the NC films were studied. The modifications in the optical properties indicated that the γ radiation is a useful tool that allows the application of the resulting PC/PS/PEO/ZnS NC films in optoelectronic devices. Furthermore, the color differences between the pristine and irradiated films were evaluated using the CIE color differences technique. The pristine film was uncolored but showed significant color changes when irradiated with γ radiation up to 180 kGy, the maximum dose used.