eV For Zn Research Articles

Bismuthene as a novel anode material of magnesium/zinc ion batteries with high capacity and stability: a DFT calculation.

In our research, we utilize density functional theory (DFT) to explore the properties of magnesium and zinc atoms adsorbed on bismuthene. Our findings indicate that the hollow site is the most favorable adsorption site for Mg and Zn atoms on bismuthene. The results indicate that Mg and Zn adsorption on the bismuthene surface results in significantly high conductivity, with notable adsorption energies of -3.38 eV for Mg and -3.91 eV for Zn. The bismuthene structure can adsorb 9 Mg and 18 Zn atoms with negative average adsorption energy. These findings suggest excellent stability of bismuthene during the adsorption of magnesium and zinc. Notably, we propose theoretical storage capacities of 2308 mA h g-1 for magnesium-ion batteries (MgIBs) and 4616 mA h g-1 for zinc-ion batteries (ZnIBs), while maintaining structural stability during the adsorption of these metal ions. The observed average open-circuit voltages for bismuthene are 0.01 V for Mg and 0.03 V for Zn, with the material retaining its metallic properties throughout the adsorption process. Furthermore, the calculated diffusion barriers for Mg and Zn are 0.1 eV and 0.21 eV, respectively. Our findings like storage capacity, diffusion energies, and low OCV surpass those of most studied two-dimensional materials, positioning bismuthene as a promising anode material for metal-ion rechargeable batteries.

Exploring the synergistic influence of Cu and Co co-doping on the optical properties of ZnO nanoparticles

In this study, we synthesized Cu and Co co-doped ZnO nanoparticles, denoted as Zn1-2xCuxCoxO (x = 0.01, 0.02, 0.03), using the sol-gel auto-combustion method. Successful integration of Cu and Co elements into the ZnO host lattice was confirmed through a comprehensive array of spectroscopic techniques. Structural analysis revealed the persistence of a hexagonal wurtzite crystal structure with some distinct microstructural variations across all samples. Alteration in lattice parameters and dislocation density strongly suggests the successful incorporation of Cu2+ and Co2+ ions within the ZnO lattice. A prominent increase in crystallite size from 27.19 nm to 33.46 nm was observed with the increase in doping concentration. Field emission scanning electron microscopy showed a combination of uniformly distributed spherical and hexagon-like structures. Furthermore, UV–Visible absorption spectra demonstrated a proportional enhancement in energy band gap from 2.14 eV for Zn0.98Cu0.01Co0.01O to 2.40 eV for Zn0.94Cu0.03Co0.03O. The Burstein−Moss effect was invoked to elucidate the observed blue shift in absorption spectra and energy band gaps, further solidifying our findings. The systematic and substantial correlation between dopant concentration and energy band gap signifies that the co-doping of Cu and Co is a viable strategy for engineering the band gap of ZnO. This collective investigation unveils the substantial potential of Cu and Co co-doping in ZnO nanoparticles for advanced optoelectronic applications, paving the way for tailored optical and photonic functionalities.

Room-Temperature Ferromagnetism in Mn-Doped ZnO Nanoparticles Synthesized by the Sol-Gel Method.

In the current work, pure ZnO and Mn-doped ZnO nanoparticles were synthesized by the sol-gel autocombustion method. Structural analysis and phase determination were done by X-ray diffraction, and a hexagonal wurtzite structure was exhibited with disparate microstructures for all samples. Mn2+ ions were well composed, as evidenced by the fluctuation of lattice parameters, dislocation density, and lattice strain. Crystallite size decreases from 38.42 to 27.54 nm by increasing the doping concentration. Field emission scanning electron microscopy results shows the combination of evenly distributed spherical-like and hexagon-like structures. Fourier transform infrared spectra revealed that when Mn content increased, the absorption bands red-shifted. The drop in the energy band gap from 3.25 eV for ZnO to 2.99 eV for Zn0.96Mn0.04O was predicted by ultraviolet-visible absorption spectra. This red shift in the energy band gap can be explained by the sp-d exchange interaction between the band electrons of ZnO and localized d electrons of Mn. A study of magnetic properties revealed the change of the diamagnetic attribute for pure ZnO to the room-temperature ferromagnetic attribute of doped samples. In the current study, room-temperature ferromagnetism was achieved for Mn-doped ZnO nanoparticles, which can serve as a desirable option for practical applications in the future.

Facile Synthesis And Characterization Of gCN, gCN-Zn And gCN-Fe Binary Nanocomposite And Its Application As Photocatalyst For Methylene Blue Degradation

Thermal condensation method to obtain for pure graphitic carbon nitride (gCN) and two binary nanocomposites, gCN-Zn - gCN-Fe have been used in the present study. The structural, morphological, thermal and optical characterizations of the syhtesized samples were characterized with X-ray diffraction, scanning electron microscopy, thermogravimetric analysis (TGA) and UV-Vis spectroscopy. The intensity of characteristic gCN peak at (002) crystalline plane decrease with formation of binary nanocomposites was observed. The EDX spectra supports presents of Zn and Fe element in binary nanocomposites. The bandgap of pristine gCN is calculated as 2.75 eV and it decreases to 2.58 eV and 2.50 eV for Zn and Fe addition. The degradation capacity of pristine gCN and synthesized binary nanocomposites showed an enhanced photodegradation performance for binary composite relative to pristine gCN was observed. The maximum degradation performance was observed at gCN-Zn binary composite. The obtained composites with this simple synthesis method and cost effective raw materials used for the photodegradation of methylene blue dye detail.

Enhanced Magnetic, Dielectric, Optical and Ferro-Photovoltaic Properties of Barium Ferrite (BaFe2O4) Nanoparticles with Zn doping for Photovoltaic Applications

Aim: Enhanced Magnetic, Dielectric, Optical and Ferro-Photovoltaic Properties of Barium Ferrite (BaFe2O4) Nanoparticles with Zn doping for Photovoltaic Applications Background: A complete examination of structural, magnetic, di-electric, photovoltaic, and optical properties of Zn doped barium ferrite particles has been performed, using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Vibrating sample magnetometer (VSM), Impedance Analyzer, UV Visible spectroscopy, and Fluorescence spectrophotometer. Objective: The valuable results of magnetic, optical, and photovoltaic properties of Zn doped barium ferrites presented a novel idea for utilizing magnetic ferrites in photovoltaic applications. Method: Magnetic Ba1-xZnxFe2O4 (x = 0.0, 0.2, 0.3, 0.5) nanoparticles have been prepared by sol-gel auto combustion method. Result: The ferroelectricity and photovoltaic response were explored by Multiferroics system and Electrochemical impedance spectroscopy, respectively. The structure was detected orthorhombic with space group Pnma 3 for pure and Zn doped samples. The magnetization value for pure BaFe2O4 was increased from 1.4 emu/g to 15.3 emu/g for Ba0.7Zn0.3Fe2O4 sample. The ferroelectric behavior was reflected equally in pure BaF and Zn-doped samples. The photovoltaic results revealed an increase in photocurrent upon illumination in Zn = 0.3 sample. The dielectric properties showed direct relation with each other and supported ferroelectricity. The energy band gap value for pure barium ferrite (BaF) was reduced from 1.54 eV to 1.33 eV for Zn = 0.3 sample. The photoluminescence resulted in increasing emission intensity spectra for Zn = 0.3 and Zn = 0.5 at wavelength of 607 nm and 430 nm. Conclusion: The nanoparticles revealed an orthorhombic crystal structure with degraded particle size from 43-26.5 nm with increasing concentration of Zn doping. The same movement was followed by grain size from 245 to 33 nm. The lattice constant ‘a’, micro-strain, and dislocation density were increased. The growth of spherical nanoparticles and the desired composition of chemical bonds were verified by SEM and FTIR individually. The magnetization was upgraded from 1.4 emu/g to 15.32 emu/g, while coercivity was lessened with doping.

Room-Temperature Ferromagnetism in Cu/Co Co-Doped ZnO Nanoparticles Prepared by the Co-Precipitation Method: For Spintronics Applications

In current work, pure ZnO and Zn0.96–xCu0.04CoxO (0 ≤ x ≤ 0.05) nanoparticles were synthesized by the co-precipitation method. Structural analysis and phase determination of the formed nanoparticles was carried out using X-ray diffraction (XRD) and Williamson–Hall plots. The hexagonal wurtzite structure was manifested by all the samples with divergent microstructures. The change in lattice parameters, bond length, dislocation density, and lattice strain indicates that Cu and Co were successfully incorporated. Average crystallite size was found to be in the range of 32.16–45.42 nm for various doping concentrations. Field emission scanning electron microscopy results exhibited that the surface morphology is an amalgam of spherical-like and hexagon-like structures. Spherical-shaped grains were homogeneous and evenly distributed all over the structure. Fourier transform infrared spectra indicated that the absorption bands were blue-shifted with increasing Co concentration. The UV–visible absorption spectra showed high absorption in the UV region and weak absorption in the visible region. An increase in the energy band gap for the maximum absorption peak was observed from 3.49 eV for ZnO to 3.88 eV for Zn0.91Cu0.04Co0.05O. The Burstein–Moss effect explained the noticed blue shift in absorption spectra and energy band gaps. The vibrating sample magnetometer study revealed the change in the diamagnetic behavior of pure ZnO to the ferromagnetic behavior of the prepared nanoparticles at room temperature for different doping concentrations. In the current study, we have developed the room-temperature ferromagnetism (RTFM) for Cu and Co co-doped ZnO nanoparticles. Since RTFM is the key objective for dilute magnetic semiconductors, therefore it can be served as the desirable expectant for spintronics applications with improved functionalities and device concepts.

Structural Characterization and Antimicrobial Studies of Some New Mixed Ligand Complexes of Lomefloxacin and 3‐(Bromoacetyl)coumarin with Some Metals

AbstractThe interaction of Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), Cu(II) (5), and Zn(II) (6) with lomefloxacin (LFX) in the existence of 3‐(bromoacetyl)coumarin (BAC) and NaOH in a 1 : 1 : 1 : 1 molar ratio resulted in the formation of unique mixed ligand metal complexes. The ability of two ligands to chelate metal ions was investigated by elemental analysis, molar conductance, effective magnetic moments FT‐IR, ultraviolet‐visible (UV‐Vis), 1H NMR spectra and thermogravimetric analyses (TG‐DTG). FT‐IR spectra of the complexes suggest that LFX reacted with metal ions as bi‐dentate through pyridone oxygen and carboxylate oxygen. BAC also interacts as bi‐dentate through oxygen of α,β‐unsaturated ketone and oxygen of lactone carbonyl of coumarin. These chelates are electrolytes, according to conductivity experiments, with a 1 : 1 ratio for Mn(II), Fe(II), and Zn(II) and a 1 : 2 ratio for Co(II), Ni(II), and Cu(II). Electronic and magnetic data revealed an octahedral shape for all compounds. The thermodynamic parameters of thermal breakdown processes such as Ea, ΔH*, ΔS* and ΔG* were determined from TG and DTG curves using Coats‐Redfern (CR) and Horowitz‐Metzeger (HM) techniques for LFX, BAC and their metal complexes. The structural geometry of the complexes is confirmed by molecular modeling studies. The findings show that the complexes are soft with regard to ligands, with values ranging from 0.058 eV for Fe(II) complex to 0.090 eV for Zn(II) complex and 11.11 to 17.24 eV for LFX and BAC, respectively, and 0.121, 8.26 eV and 0.111, 9.009 eV for LFX and BAC. The ligands and their complexes were tested in vitro for antibacterial activity against a variety of bacterial and fungal strains, and the results revealed that the complexes had significantly higher potency than the parent drug.

XANES reflects coordination change and underlying surface disorder of zinc adsorbed to silica

Zinc K-edge X-ray absorption near-edge structure (XANES) spectroscopy of Zn adsorbed to silica and Zn-bearing minerals, salts and solutions was conducted to explore how XANES spectra reflect coordination environment and disorder in the surface to which a metal ion is sorbed. Specifically, XANES spectra for five distinct Zn adsorption complexes (Znads) on quartz and amorphous silica [SiO2(am)] are presented from the Zn-water-silica surface system: outer-sphere octahedral Znads on quartz, inner-sphere octahedral Znads on quartz, inner-sphere tetrahedral Znads on quartz, inner-sphere octahedral Znads on SiO2(am) and inner-sphere tetrahedral Znads on SiO2(am). XANES spectral analysis of these complexes on quartz versus SiO2(am) reveals that normalized peak absorbance and K-edge energy position generally decrease with increasing surface disorder and decreasing Zn-O coordination. On quartz, the absorption-edge energy of Znads ranges from 9663.0 to 9664.1 eV for samples dominated by tetrahedrally versus octahedrally coordinated species, respectively. On SiO2(am), the absorption-edge energy of Znads ranges from 9662.3 to9663.4 eV for samples dominated by tetrahedrally versus octahedrally coordinated species, respectively. On both silica substrates, octahedral Znads presents a single K-edge peak feature, whereas tetrahedral Znads presents two absorbance features. The energy space between the two absorbance peak features of the XANES K-edge of tetrahedral Znads is 2.4 eV for Zn on quartz and 3.2 eV for Zn on SiO2(am). Linear combination fitting of samples with a mixture of Znads complex types demonstrates that the XANES spectra of octahedral and tetrahedral Znads on silica are distinct enough for quantitative identification. These results suggest caution when deciphering Zn speciation in natural samples via linear combination approaches using a single Znads standard to represent sorption on a particular mineral surface. Correlation between XANES spectral features and prior extended X-ray absorption fine structure (EXAFS) derived coordination environments for these Znads on silica samples provides insight into Zn speciation in natural systems with XANES compatible Zn concentrations too low for EXAFS analysis.

Structural, optical, and magnetic properties of nanostructured Ag-substituted Co-Zn ferrites: insights on anticancer and antiproliferative activities

Magnetic spinel ferrite nanoparticles possess high scientific attention for the researchers attributed to its broad area for biomedicine purposes, comprising cancer magnetic hyperthermia and targeted drug delivery. Herein, we report the ultrasound irritation assisted the sol–gel method for the spinel Zn0.5Co0.5-xAg2xFe2O4 (x = 0.00, 0.10, 0.20, and 0.30) nanoparticles (NPs) synthesis. The Rietveld refinement patterns revealed the successful synthesis of the cubic structure Zn0.5Co0.5-xAg2xFe2O4 and the crystallite size ranged from 14.1 nm to 18.4 nm. Also, the optical band gap decreased from 2.39 eV for Co-Zn ferrite to 2.20 eV for Zn0.5Co0.2Ag0.6Fe2O4 sample. Electron paramagnetic resonance spectroscopy was used to study ferromagnetic resonance characteristics of the Zn0.5Co0.5-xAg2xFe2O4 samples. The resonance field was increased from 2512.2 Gauss for Co-Zn ferrite sample to 2834.8 Gauss for Zn0.5Co0.2Ag0.6Fe2O4 sample, while the line width decreased from 2401.3 to 1990.1 Gauss. Also, the saturation was reduced from 45.68 emu.g−1 for the pristine Zn0.5Co0.5Fe2O4 sample to 22.20 emu.g−1 for Zn0.5Co0.2Ag0.6Fe2O4 sample. Furthermore, cytotoxicity of Zn0.5Co0.2Ag0.6Fe2O4 NPs against human breast cancer MCF-7, HepG2 liver cancer, and LoVo colorectal cancer cells was examined. The cytotoxicity of Zn0.5Co0.2Ag0.6Fe2O4 on the previous cancer cell lines resulted in inhibition of cell growth estimated by MTT assay. The exposure of MCF-7, HepG2, and LoVo cancer cells to Zn0.5Co0.2Ag0.6Fe2O4 NPs for 24hs proved a significant apoptotic activity by significant induction of p53 gene expression and caspase activity and antiproliferative activity by amelioration of MMP-2 activity and Bcl-2 gene expression.

Spectroscopic characterization, thermogravimetric, DFT and biological studies of some transition metals complexes with mixed ligands of meloxicam and 1,10 phenanthroline

A series of biologically active complexes were prepared using meloxicam (H2mel) and 1,10-phenanthroline monohydrate (Phen) as ligands. The compositions of all complexes were elucidated by infrared, electronic absorption and 1H NMR spectroscopy, elemental analyses, magnetic moments, conductance and TG-DTG measurements. The analytical and spectroscopic data revealed that H2mel acts as a mono basic bidentate ligand binding through the oxygen of the amide and nitrogen of the thyizol groups, whereas Phen is coordinated through the two nitrogen atoms with slightly distorted octahedral geometry. The geometries of ligands and complexes were studied using density functional theory to predict properties of materials carried out using the hybrid density functional B3LYP level of theory. All studied complexes can be characterized as chemically soft with respect to the H2mel where η varied from 0.053 eV for Fe(III) complex to 0.089 eV for Zn(II) complex and σ varied from 11.236 to 18.868 eV, while η and σ for H2mel are 0.14 and 7.14 eV, respectively. The antibacterial activities of the ligands and metal complexes have been tested and the data showed that the complexes are significantly active against some bacterial species compared with H2mel.

Enhanced photocatalytic activity of Ho3+ doped ZnO NPs synthesized by modified sol-gel method: An experimental and theoretical investigation

All nanocrystalline ZnO nanoparticles (NPs) were synthesized via modified sol-gel method and origin of the enhanced photocatalytic activity of the Zn1−xHoxO (x = 0.01, 0.03 and 0.05) NPs were investigated. Structural properties and morphological evolution were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM), respectively. Ultraviolet visible (UV-Vis) spectroscopy showed red shift of optical band gap on doping with minimum band gap of 3.10 eV for Zn0.97Ho0.03O. Photoluminescence (PL) spectroscopy showed decrease in electron-hole recombination rate with increasing doping up to 3 mol% doping. Photocatalytic activity was measured from degradation of rhodamine B (RhB) and reaction kinetics were analyzed. Theoretical study showed good agreement with experimental band gap results. Decreased electron-hole recombination rate with doping due to electron trapping by partially filled 4f orbitals of Ho3+ ions, change in NPs morphology and the red shift of the optical band gap resulted the best photocatalytic performance of Zn0.97Ho0.03O NPs.

Studies on Surface Morphology and Electrical Conductivity of PS Thin Films in Presence of Divalent Complexes

Optical properties and surface morphology of pure and doped Polystyrene films with different divalent metals of Zn, Cu and Sn and one concentration percentage have been studied. Measurements of UV-Vis spectrophotometer and AFM spectroscopy were determined. The absorbance, transmittance and reflectance spectrums were used to study different optical parameters such as absorption coefficient, refractive index, extinction coefficient and energy gap in the wavelengths rang 200-800nm. These parameters have increased in the presence of the metals. The change in the calculated values of energy gaps with doping metals content has been investigated in terms of PS matrix structural modification. The value of optical energy gap was found decreasing from 4.5eV of pure PS to reach 4.45, 4.38 and 4.32eV for Zn, Cu and Sn respectively. Measurement by AFM spectroscopy was done for two and three dimensional topographic images. From figures, the data of roughness average were 7.29, 7.31, 3.37 and 6.73nm for samples (Blank, Zn, Cu and Sn) respectively.

Optoelectronic characterization of Zn1-xCdxO thin films as an alternative to photonic crystals in organic solar cells

Zn1−xCdxO thin films spanning the whole composition range have been explored as an active region in photonic devices. The precise control of the Cd concentration, as well as its crystalline phase, allowed to characterize their optoelectronic properties. However, its application as a transparent conducting oxide material in photonics has yet to be unveiled. Here, we fabricated Zn1−xCdxO thin films via the spray pyrolysis method and confirmed their composition via Energy-dispersive X-ray spectroscopy measurements. We obtained their dielectric function through spectroscopy ellipsometry over the 300-3200 nm wavelength range and validated our model performing transmittance measurements. We observed a nonlinear red-shift of the optical bandgap while increasing Cd concentration, from 3.2 eV for ZnO to 2.9 eV for Zn0.10Cd0.90O. We found that the samples with Cd concentration > 50% have sheet resistance as low as 19.8 Ω/Square. The use of alloyed metal oxides on organic solar cells as photonic crystal structures (PhC) was also evaluated by performing finite-difference time-domain simulations. We saw an enhancement in the light absorption leading to a 39.75% increase of the short-circuit current for Zn0.25Cd0.75O PhC when compared to organic solar cells with no PhC structure.

Mixed structure Zn(S,O) nanoparticles: synthesis and characterization

Abstract In the present work, mixed structure Zn(S,O) nanoparticles have been synthesized using solution based chemical coprecipitation technique. Two different zinc sources (Zn(CH3COO)2·2H2O and ZnSO4·7H2O) and one sulfur source (CSNH2NH2) have been used as primary chemical precursors for the synthesis of the nanoparticles in the presence and absence of a capping agent (EDTA). The structural, morphological, compositional and optical properties of the nanoparticles have been analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transmission infra-red (FT-IR) and UV-Visible (UV-Vis) spectroscopy. XRD revealed the formation of mixed phases of c-ZnS, h-ZnS and h-ZnO in the synthesized nanoparticles. The surface morphology was analyzed from SEM micrographs which showed noticeable changes due to the effect of EDTA. EDX analysis confirmed the presence of zinc, sulfur and oxygen in Zn(S,O) nanoparticles. FT-IR spectra identified the presence of characteristic absorption peaks of ZnS and ZnO along with other functional group elements. The optical band gap values were found to vary from 4.16 eV to 4.40 eV for Zn(S,O) nanoparticles which are higher in comparison to the band gap values of bulk ZnS and ZnO. These higher band gap values may be attributed to the mixed structure of Zn(S,O) nanoparticles.

Structural optical and magnetic properties of transition metal doped ZnO magnetic nanoparticles synthesized by sol-gel auto-combustion method

Abstract Transition metals, such as chromium (Cr) and manganese (Mn) doped zinc oxide (ZnO) magnetic nanoparticles, were synthesized via sole gel auto-combustion method. The prepared magnetic (Zn1−(x+y)MnxCryO, where x, y = 0, 0.02, 0.075) nanoparticles were calcined in an oven at 6000 °C for 2 hours. The morphologies of the nanoparticles were investigated using different techniques. X-ray diffraction (XRD) analysis revealed that the hexagonal wurtzite structure of the synthesized nanoparticles was unaffected by doping concentration. The crystallite size measured by Scherrer formula was in the range of 32 nm to 38 nm at different doping concentrations. Nanosized particles with well-defined boundaries were observed using a field emission scanning electron microscopy (FE-SEM). Fourier transform infrared (FT-IR) spectra showed a wide absorption band around 1589 cm−1 in all the samples, corresponding to the stretching vibration of zinc and oxygen Zn–O bond. A blue shift in optical band gaps from 3.20 eV for ZnO to 3.08 eV for Zn0.85Mn0.075Cr0.075O nanoparticles was observed in diffuse reflectance spectra, which was attributed to the sp-d exchange interactions. The field-dependent magnetization M-H loops were measured using vibrating sample magnetometer (VSM). The VSM results revealed diamagnetic behavior of the ZnO nanoparticles which changed into ferromagnetic, depending on the doping concentration and particle size. The compositions of Zn, Cr, Mn and O in the prepared samples were confirmed by using the energy dispersive X-ray spectroscopy (EDX). Our results provided an interesting route to improve magnetic properties of ZnO nanoparticles, which may get significant attention for the fabrication of magnetic semiconductors.

Thin Film Zn-Mg-Al-O Produced by r. f. Sputtering Used in Antimony Sulfide Solar Cells

Zn0.80Mg0.17Al0.03O (AZMO) thin film of 180–200 nm in thickness was produced by radio frequency (r. f.) argon-ion sputtering from commercial ZnO:Al and Mg-metal targets with 150 and 200 W of applied r. f. power. AZMO film is of bandgap 3.62 eV, compared with 3.25 eV for Zn0.96Al0.04O (AZO) film. The electrical conductivity (σ) of AZO film is 80 Ω−1 cm−1, which reduces to 0.2 Ω−1 cm−1 when the film was heated in air at 300°C. For AZMO film these values are, 10 and 10−4 Ω−1 cm−1, respectively. Thus, the AZMO film is converted to a high resistive transparent n-type film for solar cell. Such films on F-doped SnO2 (FTO) film was used in antimony sulfide solar cell: FTO/AZMO/Sb2S3/C-Ag. This cell showed notable increase in the short circuit current density (10.86 mA/cm2) with respect the solar cell, FTO/CdS/Sb2S3/C (6.28 mA/cm2). The increase is due to improved external quantum efficiency toward the ultraviolet region. The open circuit voltage of these cells are 0.478 V and 0.627 V, respectively, with conversion efficiencies of 1.3% and 1.13%.

Synthesis and characterization of transition-metals-doped ZnO nanoparticles by sol-gel auto-combustion method

Transition-metals chromium (Cr) and iron (Fe) doped ZnO nanoparticles are synthesized by sol-gel auto-combustion and characterized by different techniques. X-ray diffraction (XRD) analysis reveals that the synthesized nanoparticles have a typical hexagonal wurtzite structure. The crystallite size measured by Scherrer's formula was in the range of 36–38 nm at different doping concentrations. The scanning electron microscope (SEM) results show the nano-sized nanoparticles with well-defined boundaries are observed. Fourier transform infrared (FTIR) spectra show a wide absorption band at 1589 cm−1 for whole composition range, corresponding to the stretching vibration of zinc and oxygen ZnO bond. A decrease in optical band gaps from 3.20 eV for ZnO to 3.16 eV for Zn0.95Cr0.05Fe0.05O nanoparticles was observed by UV–Vis spectroscopy analysis. The field-dependent magnetization M-H loops measured by using vibrating sample magnetometer (VSM) reveal that diamagnetic behavior of ZnO nanoparticles changed into ferromagnetic depending on the doping concentration. Our results provided an active route to improve magnetic properties of the ZnO nanoparticles, which may get considerable attention in the coming days.

Potential efficiency improvement of Cu (In, Ga) Se2 thin-film solar cells by the window layer optimization

In this paper, an initial model based on a CIGS experimental device has been established. Afterwards, the conventional i-ZnO layer replaced by ZnO1-xSx or Zn1-yMgyO layers as window layer and the solar cell performance analyzed. The estimated optical bandgap (Eg) of Zn1-yMgyO material is linearly enhanced from 3.3 eV for pure ZnO to 4.1 eV for Zn0.6Mg0.4O. Also, Eg for ZnO1-xSx material is variable between 2.83 eV–3.76 eV that is wider than pure ZnO. The AlZnO/ZnO1-xSx/CdS/CIGS structure when 0.4 < x < 0.6 and the AlZnO/Zn1-yMgyO/CdS/CIGS structure when 0.055 < y < 0.2 are the proposed solar cells with 21.15% efficiency.

The structural, elastic, electronic, magnetic and optical properties of the Zn0.75V0.25X (X = S, Se or Te)

The structural, elastic, electronic, magnetic and optical properties of the Zn0.75V0.25X (X = S, Se or Te) have been investigated by the spin-polarized first-principles calculations. The optimized lattice constant increases with the increasing anions radius of S2−, Se2− and Te2−. All the Zn0.75V0.25X systems show the ductile and half-metallic characters. The spin exchange splitting energy $${\Delta _x}(d)$$ increases but the absolute value of the exchange splitting energy $${\Delta _x}(pd)$$ decreases for Zn0.75V0.25S, Zn0.75V0.25Se and Zn0.75V0.25Te successively, and the p–d exchange constant $${N_0}\beta$$ is greater than s–d exchange constant $${N_0}\alpha$$. The static dielectric constants $${\varepsilon _1}(0)$$, the maximum value of $${\varepsilon _2}(\omega )$$, static refractive indexes $$n(0)$$ and the maximum value of $$k(\omega )$$ get the biggest values for Zn0.75V0.25Se among Zn0.75V0.25X (X = S, Se or Te). Compared with pure ZnX, the new absorption peaks occur in the energy range of 0–1.4 eV for Zn0.75V0.25X systems. The results provide a certain degree of helpful theoretical guidance for the application of the Zn0.75V0.25X in spintronics devices and optical detectors.

Preferential regions of growth of chemical bath deposited ZnO and Zn(OH)2 thin films at room conditions

Zinc oxide (ZnO) and zinc hydroxide (Zn(OH)2) films were deposited onto glass substrates at room conditions (25°C and atmospheric pressure) by the chemical bath deposition technique. ZnSO4, KOH, and NH4NO3 were used as chemical reagents for the chemical bath. The species distribution diagrams and the solubility curves were used to find the most adequate chemical conditions for the selective film deposition according to the concentrations and type of chemical reagents. The selective deposition of ZnO and/or Zn(OH)2 was achieved by adjusting the pH of the chemical bath in the range from 11.35 to 12.30, where three regions of growth were determined. The optical bandgap energy measured on the films ranged from 3.31eV for Zn(OH)2 to 3.41eV for ZnO. Lower values of Urbach energy were found when the ZnO formation was dominant. X-ray diffraction analysis showed that the pH of the chemical bath influences on the crystallinity of the films, where better crystallinity was observed for films with higher presence of ZnO. An aging experiment to evaluate the stability of the ZnO 15weeks after the deposition process was carried out.