2θ Degree Research Articles

First principles study of chromium-based hydrides for optoelectronics and hydrogen storage applications

The first-principles study employed on chromium-based hydride XCrH3 (X: Na, K) is the first time studied and investigated different physical properties incorporated for optoelectronics and hydrogen storage applications. The structural properties results revealed that these materials have cubic phases, with lattice constants are 3.54 Å (NaCrH3), and 3.74 Å (KCrH3), which was also confirmed by the XRD analysis. The XRD results revealed that the intensity of KCrH3 is shifted towards to lower angle (2θ) degree due to high lattice constants and inter-planner distance. Moreover, both materials exhibited thermodynamically and mechanically stable due to negative formation energy, and elastic constants, and obeyed the Born approximation criteria. The phonons dispersion curve shows that XCrH3 is dynamically stable due to no imaginary frequency presence. Electronic properties found that current materials have metallic characteristics, due to zero band-gap energy, which plays a vital role in hydrogen storage applications. Magnetic properties exhibited paramagnetic behavior of current materials highly contributed to hydrogen storage application due to unpaired electrons and studied materials have spin-polarized magnetic nature. However, elastic properties confirmed that these materials are found hard, and brittle, with an ionic bonding nature between the atoms, and an anisotropic character. Besides this, different optical parameters have studied like as conductivity, absorption coefficient, refractive index, reflectance, and loss function and the results revealed that the examined materials dominated the role in LED, sensors, solar cells, and optoelectronics applications. Thermal analysis revealed that increasing temperature increases energy and entropy but decreases free energy. Among the studied materials, NaCrH3 has a high gravimetric ratio of 3.87 wt%, and KCrH3 is 3.21 wt%. These materials provided new potential for hydrogen storage applications.

Biogenic one-step synthesis of silver nanoparticles using Quisqualis indica linn flower extract: Characterization, molecular docking, and DFT studies

The present study reports a one-step, eco-friendly, and green synthesis route of silver nanoparticles (AgNPs) from the flower extract of Quisqualis indica Linn. Analytical techniques like Ultraviole-visible (UV–Vis), Field emission scanning electron microscope (FESEM), and X-ray diffraction (XRD) were used to investigate different physicochemical characteristics of AgNPs. The UV–Vis spectrum revealed the maximum absorption at 455 nm and FESEM images confirmed that the synthesis produces stable, polydisperse with a spherical, rod-shaped, triangular, and hexagon shape. XRD analysis at 2θ degrees of 38.1o, 44.3o, 64.7o, and 77.7o corresponding to the (111), (200), (220), and (311) planes, respectively, Bragg’s reflections of the face-centered cubic crystalline structure. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the carbonyl and alcoholic groups of the different compounds of the extract of Quisqualis indica Linn flowers were majorly responsible for being the stabilizer and a capping agent of AgNPs. Furthermore, the quantum chemical parameters of β-Sitosterol (1), Brinzolamide (2), Gallic Acid (3), L-Asparagine (4), L-Proline (5), Quisqualic Acid (6), Quinoline-4-Carbonitrile (7), Quercetin (8), and Rutin (9) compounds present in the flowers of Quisqualis indica Linn are also calculated based on density functional theory (DFT). In silico study, a method such as molecular docking was carried out to determine the binding affinity of compounds (1–9) with presentations of Gram-positive bacteria (PDB ID: 2MLM) and Gram-negative bacteria (PDB ID-1KZN). Compounds (1), (2), (7) and (8) had a better score of binding toward the selected proteins. Overall, our findings shed light on the green synthesis of silver nanoparticles and it could be a potential candidate for the pharmaceutical industry against topical pathogens.

Investigations on structural, photoluminescent, and photometric properties of poly(vinyl alcohol)-capped Mn doped-ZnO nanoparticles for white light emission

In this paper, luminescent Mn-doped ZnO nanoparticles (NPs) and poly(vinyl alcohol) (PVA) capped Mn-doped ZnO nanocomposite materials were successfully synthesized by the chemistry route. The studied results indicate that the diffraction peaks of Mn-doped ZnO NPs (2, 4, and 7% Mn) are slightly shifted to the lower 2θ degree angle compared to undoped-ZnO NPs. In contrast, PVA capped Mn-doped ZnO nanocomposite shows a systematic shift of X-ray diffraction (XRD) peaks at larger diffraction angles. These samples fluoresce strongly in the visible wavelength of 380–700 nm. The near-infrared (NIR) emission bands in the 740 nm–1100 nm range are due to the shift of XRD peaks diffraction and the transition between defect states within the ZnO crystal. Photometric and chromatic parameters of PVA capped-2%Mn doped-ZnO NPs are CIE (x, y) ≈ (0.3769, 0.3987), CCT ≈ 4238 (K), Duv = 0.0110, CRI (Ra) = 80, CQS = 84, LER = 164 (lm/Wotp), and S/P ratio = 1.70. Luminescent PVA capped ZnO NPs possess CIE (x, y) ≈ (0.3598, 0.3748), CCT ≈ 4592 (K), Duv = 0.0057, CRI (Ra) = 85, CQS = 87, LER = 207 (lm/Wotp), and S/P ratio = 1.83. The studied results indicate that these luminescent materials are suitable for developing a white light emission layer in the structure of light-emitting devices.

Thermal expansion of Crofer 22 APU steel used for SOFC interconnect using in-situ high temperature X-ray diffraction

Crofer 22 APU is ferritic stainless steel extensively used as metallic interconnect material in Solid Oxide Fuel Cell (SOFC) applications. The interconnects are exposed to both oxidizing and reducing atmospheres at high temperatures. As SOFCs are operated above 700 °C, understanding the thermal expansion behavior of the interconnect material with other components (anode, cathode, electrolyte) of the fuel cells is essential. Metallic interconnects should have a matchable thermal expansion to other ceramic materials such as anode, cathode, and solid electrolyte used in SOFCs. The present study evaluates the thermal expansion of Crofer 22 APU steel from 25 to 950 °C in a controlled atmosphere (10-4 mbar pressure) using in-situ high-temperature X-ray diffraction (XRD). The XRD patterns were analyzed using the ‘High Score Plus Software’ attached to the system, and the phases were identified using the standard Crystallographic Open Database (COD). The coefficient of thermal expansion (CTE) was determined based on the change in lattice parameter/peak shift to a lower 2θ value as a function of temperature. The normal XRD data showed no oxide formation on the Crofer steel after heating until 950 °C in in-situ high-temperature conditions.The peak shift to the lower 2θ degree observed in the XRD data was due to the relaxation of residual stress upon heating. The isothermal section and phase fraction of Crofer 22 APU alloys are analyzed with the help of thermo-calc with the iron database of TCFE7. The Fe-rich bcc phase was found to be stable up to high temperatures. The major phases are the Fe-rich bcc, Cr-rich BCC, and sigma phase in the solid state. The minor phases are FCC, M3P, TiC, Laves, and Ti4C2S2. The calculated lattice parameter of the Fe-rich BCC phase matches with the experimentally calculated data using XRD. The thermal expansion of Crofer 22 APU was found to be 11.9181 × 10-6 /°C at 950 °C. The in-situ high-temperature XRD technique has been an effective methodology for determining the thermal expansion behavior of the as-received Crofer steel.

Simultaneous removal of Cu (II) and Cr (VI) ions from petroleum refinery wastewater using ZnO/Fe3O4 nanocomposite

The presence and removal of heavy metals such as Cu(II) as well as Cr(VI) in petroleum refinery wastewater calls for concerted efforts due to their mobility, toxicity, bioaccumulation, and non-biodegradability in the environment. In this present work, zinc oxide (ZnO), iron oxide (Fe3O4) nanoparticles and ZnO/Fe3O4 nanocomposites were synthesized via simple sol-gel and chemical reduction methods; characterized using different analytical tools and then applied as nanoadsorbent to sequester Cu(II) and Cr(VI) ions from Petroleum Refinery wastewater via batch adsorption process. Cu(II) and Cr(VI) adsorption processes were examined with respect to contact time (kinetic effect), nanoadsorbent dosage, isotherm equilibrium, and thermodynamic parameters. ZnO/Fe3O4 nanocomposites with higher surface area (39.450 m2/g) have a mixture of rod-like and spherical shapes as compared to ZnO and Fe3O4 nanoparticles with spherical shape only and surface areas of 8.62 m2/g and 7.86 m2/g) according to the high-resolution scanning electron microscopy (HRSEM) and Brunauer–Emmett–Teller (BET) analysis. The X-ray diffractometer (XRD) results revealed the formation of hexagonal wurtzite structure of ZnO and the face-centered cubic structure phase of Fe3O4 nanoparticles, after the formation of the ZnO/Fe3O4 nanocomposites the phases of the nanoparticles were not affected but the diffraction peaks shifted to higher 2θ degree. The average crystallite size of ZnO and Fe3O4 nanoparticles and ZnO/Fe3O4 nanocomposites were 20.12, 26.36 and 14.50 nm respectively. The maximum removal efficiency of Cu (II) (92.99%) and Cr (VI) (77.60%) by ZnO/Fe3O4 nanocomposites was higher than 85.83%; 65.19% for Cu (II) and 80.57%; 62.53 for Cr (VI) using ZnO and Fe3O4 nanoadsorbents individually under the following conditions: contact time (15), dosage (0.08 g) and temperature (30 °C). The experimental data for Cu (II) and Cr (VI) ion removal fitted well to the pseudo-second-order kinetic and Langmuir isotherm models. The thermodynamic study suggested that the removal of the two metal ions from petroleum wastewater was endothermic. The reusability study after the fourth adsorption-desorption cycle indicated the stability of ZnO/Fe3O4 nanocomposites with 85.51% and 69.42% removal efficiency of Cu (II) and Cr (VI). The results showed that ZnO/Fe3O4 nanocomposite achieves higher performance than ZnO and Fe3O4 alone in the removal of Cu (II) and Cr (VI) ions from the petroleum refinery wastewater.

Physicochemical Characteristics and Occupational Exposure of Silica Particles as Byproducts in a Semiconductor Sub Fab.

This study aimed to elucidate the physicochemical characteristics and occupational exposure of silica powder and airborne particles as byproducts generated from the first scrubbers of chemical vapor deposition and diffusion processes during maintenance in a semiconductor facility sub fab to reduce unknown risk factors. The chemical composition, size, morphology, and crystal structure of powder and airborne particles as byproducts were investigated using a scanning electron microscopy and transmission electron microscopy equipped with an energy dispersive X-ray spectroscopy, and an X-ray diffraction. The number and mass concentration measurements of airborne particles were performed by using an optical particle sizer of a direct-reading aerosol monitor. All powder and airborne particle samples were mainly composed of oxygen (O) and silicon (Si), which means silica. The byproduct particles were spherical and/or nearly spherical and the particle size ranged from 10 to 90 nm, based on primary particles. Most of the particles were usually agglomerated within a particle size range from approximately 100 nm to 35 µm. In addition, most of the powder samples exhibited diffraction patterns with a broad and relatively low intensity at 2θ degrees 21.6–26.7°, which is similar to that of pure amorphous silica. The above results show the byproduct particles are amorphous silica, which are considered a less toxic foam compared to crystalline silica. The number and mass concentrations of PM10 (particles less than 10 µm in diameter) ranged from 4.250–78.466 particles/cm3 and 0.939–735.531 µg/m3, respectively. In addition, 0.3–1.0 and 2.5–10 µm particles occupied the highest portion of the number and mass concentrations, respectively. Meanwhile, several peak exposure patterns were observed at a specific step, which is the process of removing powder particles on the inner chamber and cleaning the chamber by using a vacuum cleaner and a clean wiper, during the maintenance task.

Photocatalytic destruction and adsorptive processes of methylene blue by potassium titanate

Photocatalytic destruction and adsorptive processes of methylene blue aqueous solutions on potassium titanate surface obtained by the method of alkaline melting of ilmenite of Irshansk deposit (Ukraine) with KOH at a molar ratio of 1: 2 at 453 K were studied. It was determined that the main reflexes of potassium titanate are in the range of 29–34, 46 and 58 2θ degrees, which indicates the orthorhombic structure group Cmcm. The dye adsorption on the titanium dioxide and potassium titanate surfaces was found to be 11.52 and 21.92 mg/g, respectively. Isotherms belong to the L-type and have the form of a curve with a saturation yield. It was found that at 10 min of ultraviolet irradiation of the reaction mixture catalyst-solution with constant stirring at a maximum methylene blue concentration 10 mg / L, the degree of photocatalysis for titanium dioxide and potassium titanate 23.29% and 80.11%, respectively. Experimental data indicate the prospects for the use of potassium titanate as a catalyst for the dye decomposition.

Green synthesis, characterization, and antioxidant activity of silver nanoparticles using Stachys annua L. subsp. annua var. annua

Nanoparticles (NPs) are known as fundamental building blocks of nanotechnology. In this work, silver nanoparticles (AgNPs) were synthesized using Stachys annua L. sabsp. annua var. annua. The structure of AgNPs was elucidated by FTIR, UV-Vis, XRD, SEM analyses. The UV-Vis spectrum revealed the maximum absorption at 469 nm and SEM spectral analysis showed the formation of spherical shape AgNPs with an average size of 75.21 nm. XRD analysis at 2θ degrees of 38.1°, 44.3°, 64.4°, and 77.4° can be assigned to the (111), (200), (220) and (311) face-centered cubic crystalline structure. Antioxidant activity of extract and AgNPs was executed using the DPPH• scavenging, ABTS•+ scavenging, and reducing power assays. AgNPs and extract revealed the higher DPPH• free radical scavenging effect with the values of 10.2 ± 0.34 (lC50, µg/mL) and 9.26 ± 0.37 (lC50, µg/mL) than the standard BHT (11.13 ± 0.10, lC50, µg/mL). ABTS•+ activity of AgNPs (4.11 ± 0.04, lC50, µg/mL) and extract (3.96 ± 0.10) were found higher than that of the standard BHT. In reducing power assay, the activity of AgNPs (2.61 ± 0.02, µmol TE/mg extract) and extract (3.05 ± 0.15, µmol TE/mg extract) was lower than BHT. Hence, extract and AgNPs could be promising materials for antioxidant agents.

Biosynthesis of silver nanoparticles using Origanum majorana L. and evaluation of their antioxidant activity

The aerial part of Origanum majorana L. was extracted with deionized water and then filtered. The liquid extract was treated with silver nitrate to yield the AgNPs. The maximum absorption was observed at 483 nm in the UV-Vis spectrum. SEM analysis exhibited the spherical shape of silver nanoparticles with an average size of 72.01 nm. The XRD diffraction peaks at 2θ degrees revealed the face-centered cubic crystalline structure. Antioxidant activity of AgNPs and water extract was carried out by DPPH•, ABTS•+, and reducing power assays. AgNPs revealed higher DPPH• scavenging activity (IC50, µg/mL, 12.25) than that of the extract (21.66). Moreover, AgNPs exhibited outstanding ABTS•+ activity (3.87) compared to the standards. The reducing power activity of AgNPs was found (µmol TE/mg extract, 5.09 ± 0.21) the same as the BHT. AgNPs and extract exhibited excellent antioxidant activity promising for usage in food and pharmaceutical applications.

Indium-doped ZnOas efficient photosensitive material for sunlight driven hydrogen generation and DSSC applications: integrated experimental and computational approach

Electricity generation using simple and cheap dye-sensitized solar cells and photocatalytic water splitting to produce future fuel, hydrogen, directly under natural sunlight fascinated the researchers worldwide. Herein, synthesis of indium-doped wurtzite ZnO nanostructures with varying molar percentage of indium from 0.25 to 3.0% with concomitant characterization indicating wurtzite structure is reported. The shift of (002) reflection plane to higher 2θ degree with increase in indium-doping thus is a clear evidence of doping of indium in zinc oxide nanoparticles. Surface morphological as well as microstructural studies of In@ZnO exhibited generation of ZnO nanoparticles and nanoplates of diameter 10–30 nm. The structures have been correlated well using computational density functional (DFT) studies. Diffuse reflectance spectroscopy depicted the extended absorbance of these materials in the visible region. Hence, the photocatalytic activity towards hydrogen generation from water under natural sunlight as well as efficient DSSC fabrication of these newly synthesized materials has been demonstrated. In-doped ZnO exhibited enhanced photocatalytic activity towards hydrogen evolution (2465 μmol/h/g) via water splitting under natural sunlight. DSSC fabricated using 2% In-doped ZnO exhibited an efficiency of 3.46% which is higher than other reported In-doped ZnO based DSSCs.

Green synthesis of silver nanoparticles from Echinacea purpurea (L.) Moench with antioxidant profile

Nanoparticles reveal unique properties due to their application in many fields. The easy, eco-friendly, and cost-effective method for synthesis of silver nanoparticles (AgNPs) from the aerial part of Echinacea purpurea (L.) Moench was demonstrated in this work. The synthesized AgNPs were elucidated by Ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Scanning electron microscope (SEM) spectroscopic analyses. The UV-Vis spectrum revealed the maximum absorption at 481 nm and SEM spectral analysis displayed the formation of spherical shape silver nanoparticles with an average size of 68.24 nm. XRD spectral analysis at 2θ degrees of 38.1°, 44.3°, 64.4°, and 77.4° can be indexed to the (111), (200), (220), and (311) Bragg’s reflections of the face-centered cubic crystalline structure. Antioxidant activity of AgNPs and water extract were executed using the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS•+) scavenging, and reducing power assays. AgNPs and extract exhibited excellent antioxidant activity that could be promising for food and pharmaceutical utilization.

Influence of laser power and welding speed on dendrite structure growth of low power pulsed laser welded super alloy

The influence of different welding parameters like welding speed and laser power on microstructure and the mechanical properties of low power pulsed Nd: Yag laser welded Nickel based super alloy inconel 617 sheets of thickness 1.5 mm has been investigated. In the present study, the welding of the specimens was done in a single pass aimed to full depth penetration. The microstructure of the various samples at fusion zone and at heat affected zone was characterized by field effect scanning electron microscope (FESEM) while the weld size of the welded metal at different parameters were measured using optical microscope (OM). The microhardness in the various zones for the welded sample has also been investigated. The microhardness of the welded samples was compared with base metal after experimental observations. The XRD technique was used to analyze the crystallography of the material at (2θ degree). The material has been used for the present study because of its exceptional properties of heat resistant and corrosion resistant. The Nd: YAG pulsed laser has been used because of its overlapping factor during welding that reduces porosity in the weld zone.

In vitro scolicidal activity of synthesised silver nanoparticles from aqueous plant extract against Echinococcus granulosus

At present, biosynthesis of AgNPs is a very effective method to produce less toxic nanoparticles. The vision of this research is to use three different plant extracts derived from leaves of Piper nigrum, Ziziphus Spina-Christi and Eucalyptus globulus for rapid biosynthesis of AgNPs. This is in addition to investigating the scolicidal activity against Echinococcus granulosus. The methods of UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDX) were employed to characterise the nanoparticles. UV spectra disclosed a maximum absorption at 437 nm for the biosynthesised AgNPs using EUCGLO extract. The XRD patterns revealed the (fcc) structure of the AgNPs with slightly shifted characteristic peaks at 2θ degree of 37.3˚ and 43.4˚, respectively. The scolicidal activity against E. granulosus revealed that the AgNPs, which were synthesised using Eucalyptus globulus, have powered scolicidal of 47.8 % after 45 min. which is comparable to the treatment by Albendazole.

Biosynthesis, characterization and antioxidant activity of oleuropein-mediated silver nanoparticles

In this study, oleuropein was isolated from olive leaves by chromatographic method and its structure was elucidated by spectroscopic analyses such as FTIR, 1H-NMR and 13CNMR. Silver nanoparticles (AgNPs) were synthesized using oleuropein and their antioxidant activity was investigated using DPPH, ABTS•+, and FRAP assays. The AgNPs were characterized by UV-Vis, FT-IR, XRD, and SEM analyses. The absorption peak at 450 nm in UV-Vis spectrum confirmed the AgNPs formation. Scanning electron microscope (SEM) identified the formation of spherical-shaped nanoparticles with the average size of 71 nm. Rietveld analysis was carried out by X-ray diffraction data with High Score Plus software. XRD with 2θ degrees at 38.1°, 44.3°, 64.4° and 77.4° can be assigned to the (111), (200), (220) and (311) Bragg’s reflections of the face-centered cubic crystalline structure. Biosynthetic nanoparticles revealed more inhibitory effect (5.22, IC50, µg/mL) against ABTS•+ than standard BHT (7.03, IC50, µg/mL).

Effects of low-dose γ-irradiation on the structural, morphological, and optical properties of fluorine-doped tin oxide thin films

This paper presents the effects of low-dose γ-irradiation on the structural, morphological, and optical properties of Fluorine-doped tin oxide (FTO) thin films for application as a passive thermal control coating in future miniaturized lightweight spacecraft. Commercial-grade FTO films on glass substrate (Pilkington Ltd, UK) with a bulk density of 2.5 g/cm3, sheet resistance of 12 Ω.sq-1, coating thickness of 450 nm, optical band-gap of 3.80 eV, a carrier concentration of 1.50×1020 cm−3 and a mobility of 15 cm2/Vs were irradiated at room temperature and atmospheric pressure using a 60Co gamma source (with gamma energies of 1.17 MeV and 1.33 MeV) at iThemba Laboratory for Accelerator Based Sciences, Cape Town, South Africa. Each sample was exposed to γ-rays for a different span of time to achieve a series of different integrated absorbed doses of 20, 30, and 50 Gy, at a dose rate of 0.207 Gy/min. Evolution in structural properties of the films was characterized using a Bruker AXS D8 Advance XRD with Cu-Kα (λ = 1.54056 Å) scanned in the 2θ degree range of 20 – 80 degrees. Surface properties were analyzed using a VEECO Dimension 1100 AFM machine. Meanwhile, variations in optical transmittance of the films was investigated using a Cary 5000 UV-vis-NIR spectrophotometer of Varian, Inc. model internal DRA- 2500 in the wavelength range of 200 – 2500 nm. XRD results indicate an enhancement of crystallization after irradiation, slight peak shifts, and variations in crystallite sizes with increasing dose. Surface roughness decreased with increasing dose and the grain structures also seen to vary with dose. No significant variations in optical transmittance of the FTO films.

A simple method to grow up ZnO nanorods

Because of the widely used in gas sensor and light emitting diodes, zinc oxide nano structures have attract more attention. In our article, The ZnO nanorods were prepared via a simple chemical vapor deposition method on sapphire substrate. The morphology of the nanorods were characterized by SEM which told that the zinc oxide nanorods were deposited with nonuniform but have a great hexagonal structure and the XRD pattern emerged a strong ZnO (002) peak that reveals that the zinc oxide nanorods were grow up along the c-axis, meanwhile the 002 peak is shift to the higher 2θ degree which may have relation with the defect.

Truncated Spline Regression to Estimate Regression Curve of Strontium Titanate XRD Data

Characterization of ferroelectric material using X-Ray Diffraction tools (XRD) resulted in 2θ degree and intensity of diffraction data. The result of XRD characterization showed that the relationship between 2θ degree and diffraction intensity formed spectrum pattern; fluctuation of diffraction intensity value along with the increasing of 2θ degree. The high fluctuation of diffraction intensity value affected the inconsistency of mean and variance value. Thus the model used to estimate curve shape could not be analysed by parametric method which is strict with assumptions. Spline regression is a polynomial model with segmented character that has high flexibility to generate regression curve estimation through data fitting method. This research used the truncated spline regression model to estimate regression curve of Strontium Titanate (SrTiO3) and SrTiO3 doping with 2 % of RuO2 (SrTiO3+RuO2) XRD data. The best truncated spline regression model to estimate regression curve of SrTiO3 was model with 42 knots. This model has the smallest Akaike’s Information Criterion (AIC) value and the biggest R2, that is 13403.33 and 0.6503 respectively. Meanwhile, the best truncated spline regression model to estimate regression curve of SrTiO3 RuO2 was model with 37 knots. This model has the AIC value of 13953.68 and R2 of 0.6302.

Composition and strain effects in Type I and Type II heterostructure ZnSe/Cd(Zn)S and ZnSe/Cd1-xZnxS core/shell quantum dots

We investigated the effect of ternary shell alloy composition on the bandgap and diameter of core of ZnSe/Cd1−xZnxS heterostructure core/shell quantum dots, which were synthesized by using a simple colloidal technique. Characterization by using the x-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Vis absorption and fluorescence emission spectroscopic techniques indicate that (i) there is a transition of ZnSe/Cd0.6Zn0.4S Type-I heterostructure (electrons and holes tend to localize in core) to ZnSe/Cd0.75Zn0.25S quasi-Type-II heterostructures (holes tend to localized in the core and electrons are delocalized) and (ii) then after large red shift and Stock-shift in PL emission spectra but not a distinct absorption peak in UV spectra become noticeable in ZnSe/Cd0.75Zn0.25 S quasi-Type II and ZnSe/CdS Type II heterostructures (electrons are localized in core and holes are localized in shell). Furthermore, the increase of Cd:S ratio in shell alloy composition shifts the XRD peaks to lower 2θ degrees which corresponds to tensile strain in the ZnSe core. Finally, the hydrostatic interfacial strain has effect on the squeezing or stretching the capped core: A decrease of compressive force on core from ZnSe/ZnS to tensile force in ZnSe/CdS with increase in Cd:S ratio indicates that transition of compressive strain to tensile strain takes place with the transition from Type-I to II heterostructure.

Electrospinning, Functionalization and quaternization of Polyvinylbenzylchloride (PVBC) Electrospun Nanofibers

The polyvinylbenzylchloride (PVBC) was electrospun into nanofibers in a 1:1 (v/v) ratio of N,N-Dimethylformamide (DMF), Tetrahyhdrofuran solvent mixture, the surface was functionalized using ethylenediamine and finally quaternized PVBC using three different alkyl groups (CH3, C2H5 and C3H7). Fourier transform infrared (FTIR) analysis was used to characterize the functional groups present. The band assigned to 670 cm-1 v(C-Cl) disappeared completely to form a new band at 1562 cm-1 indicating the presence of NH group on the fibers. Energy dispersive x-ray spectrometer (EDX) for PVBC shows the presence of a broad peak for Cl on the unfunctionalized fiber and this peak disappears to form a sharp peak of nitrogen from the amine in ethylenediamine (EDA) of the fibers. X-ray diffraction (XRD) analysis of the fibers reveals the sharp peak on 40 (2θ) degree axis on the surface of the functionalized fibers. It was also observed that, Brunauer, Emmett, Teller (BET) surface area of the sorbent materials (PVBC) changed after the functionalization with amine.

Surface and optical properties of indium tin oxide layer deposition by RF magnetron sputtering in argon atmosphere

This study focused on the characterization and properties of transparent and conductive indium tin oxide (ITO) thin films deposited in argon atmosphere. ITO thin films were coated onto glass substrates by radio frequency (RF) magnetron sputtering technique at 75 and 100 W RF powers. Structural characteristics of producing films were investigated through X-ray diffraction analysis. UV–Vis spectrophotometer and interferometer were used to determine transmittance, absorbance and reflectance values of samples. The surface morphology of the films was characterized by atomic force microscope. The calculated band gaps were 3.8 and 4.1 eV for the films at 75 and 100 W, respectively. The effect of RF power on crystallinity of prepared films was explored using mentioned analysis methods. The high RF power caused higher poly crystallinity in the produced samples. The thickness and refractive index values for all samples increased respect to an increment of RF power and were calculated as 20, 50 nm and 1.71, 1.86 for samples at 75 and 100 W, respectively. Finally, the estimated grain sizes for all prepared films decreased with increasing of 2θ degrees, and the number of crystallite per unit volume was calculated. It was found that nearly all properties including sheet resistance and resistivity depend on the RF power.