Hexagonal ZnO Phase Research Articles

Preparation, characterization and biological activity of Co-doped ZnO nanostructured thin film: A comprehensive study on its photo-physical properties and antimicrobial efficacy against food-borne pathogen

The Co@ZnO thin film deposited on glass substrate with dopant contents of cobalt ranging from 0 to 10 % were fabricated using spray pyrolysis coating method. The prepared nanocomposite thin film was characterized by scanning electron microscopy, X-ray diffraction, UV–vis and Raman spectroscopy. Some surfaces structural probing of the deposited samples confirmed nanolamination of hexagonal wurtzite phase of ZnO with no other impurity phases and high adherence on the soda lime glass substrate. Average grain sizes (56–43 nm) and lattice strain of the films were found to be tailored with the variation of Co-dopant content, signifying phonon confinement or defect/disorder caused by the Co-dopant impurity on the ZnO host particle owing to the impurity levels and oxygen vacancy states. The film demonstrated high optical transmittance with enhanced photoabsorbtion and narrow optical band gap (3.24–2.64 eV) with increasing Co-dopant content. In evaluating its antibacterial efficacy, the Co@ZnO thin film was tested at different dopant concentration against Bacillus cereus (foodborne pathogen). The result revealed that the films exhibits excellent inhibitory effect on the pathogen, with highest activity obtained at 10 % Co@ZnO. Furthermore, a more improved inhibitory activity was recorded when at 10 % Co@ZnO dopant was exposed to UV irradiation.

Physical properties of La:ZnO thin films prepared at different thicknesses using spray pyrolysis technique

Herein we investigate the impact of film thickness on the physical properties of Lanthanum (La) doped ZnO thin films. The films were fabricated using the spray pyrolysis technique with a consistent La content of 5 weight (wt) % in the initial solution. X-ray diffraction analysis indicated the presence of a hexagonal ZnO phase with preferred orientation along the (002) direction and no other phases were detected. The crystallite sizes were calculated using the Halder-Wagner equation, with a maximum size of 16.1 nm observed for a film thickness of 106 nm. Field-emission scanning electron microscopy (FE-SEM) images revealed the formation of a continuous film with an average grain size that increased as the thickness of the film increased. The grain size ranged from 74.5 to 136 nm as the film thickness varied from 106 to 426 nm. Films with lower thicknesses up to 196 nm exhibited two band gaps at approximately 3.2 and 4 eV, while films with higher thicknesses displayed a single band gap around 3.2 eV. The refractive index dispersion for all films was modeled using the Cauchy model, with parameters showing high dependence on the thickness values.The refractive index at high frequency, as calculated using the Cauchy model, was observed to decrease with increasing film thickness, ranging from 1.87 at 106nm to 1.63 at 426nm. Similar values were obtained by fitting the optical refractive index data with the Wemple-DiDomenico relation. Additionally, the UV sensing performance of the films was evaluated against UV light of a single wavelength (365 nm) at applied voltages of 10, 20, and 30V. The rise and decay times were measured, with the film thickness of 426 nm exhibiting the shortest rise and decay times at a specific applied voltage.

Ce-doped ZnO nanonails synthesized by a simple thermal evaporation method for photocatalytic degradation

One-dimensional (1D) nanomaterials have garnered significant scientific and technological attention due to their potential applications in electronics devices, gas sensing, energy conversion, and photocatalysis. However, the development of a simple and low-cost technique for 1D nanostructure synthesis remains a challenge. The doping of ZnO nanostructures has proven to be an effective way to improve their internal properties. In this work, one-dimensional ZnO and Ce-doped ZnO nanorods and nanonails were synthesized by a simple thermal evaporation method using different weight ratios of ZnS and CeO2 precursor powders in a catalyst-free process. The effects of cerium doping concentration on the structural, morphological, and optical properties of the as-prepared samples were investigated. XRD analysis confirmed that the crystal structure was converted from the cubic ZnS phase to the hexagonal ZnO phase with increasing annealing temperatures. The UV–Vis spectra showed that the optical absorption edge of Ce-doped ZnO samples was slightly red-shifted. Additionally, the band gap energy decreases with increasing cerium concentration. SEM images showed that the morphology of the structures obtained changed from nanorods to nanonails as the Ce content increased. The incorporation of Ce ions into the ZnO matrix has been successfully confirmed by HRTEM, Raman, and EDX analysis. Photocatalytic activity studies showed that Ce-doped ZnO samples exhibited significantly enhanced photocatalytic performance compared to pure ZnO for the degradation of rhodamine B under UV radiation. These results may suggest the use of heterogeneous photocatalysis as an efficient, cheap, and environment-friendly alternative for the removal of pollutants from water and the use of Ce-doped ZnO as a promising candidate.

Electrodeposited zinc oxide nanoparticles: Synthesis, characterization, and anti-cervical cancer effects

In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized via the electrodeposition method and characterized. Then, the anticancer effects of ZnO NPs against cervical cancer HeLa cells were assessed by cell viability, oxidative stress, caspase activity, qRT-PCR, MMP, and ELISA assays. XRD analysis revealed the hexagonal wurtzite phase of ZnO. SEM image of ZnO NPs showed the homogeneous spherical/hexagonal-like structures of ZnO NPs, while TEM imaging revealed the successful synthesis of ZnO NPs with an average diameter of about 8 nm. The UV–vis absorption spectrum of ZnO NPs showed a characteristic absorption band around the wavelength of 368 nm with a band gap energy (Eg) of 3.36 eV. DLS study displayed that the obtained particle size of ZnO NPs has an average size of 29.24 nm and an average zeta potential value of −19 mV. Additionally, cellular findings indicated that the proliferation of cervical cancer HeLa cells was markedly mitigated after incubation with ZnO NPs at different concentrations of 10, 50 and 100 µg/ml, however, these concentrations were not able to trigger an apparent cytotoxic effect on HUVEC non-malignant cells. Also, it was detected that ZnO NPs led to overexpression of Bax/ Bcl-2, caspase-9/-3 genes, increased level of caspase-9/-3 activity, overproduction of MDA level, inhibition of SOD and CAT activity and reduction of GSH content, MMP collapse, and upregulation of cytoplasmic cytochrome c release. In general, these findings suggested that electrodeposited synthesized ZnO NPs can induce anticancer effects in cervical cancer HeLa cells through the mitochondrial-mediated apoptosis signaling pathway.

Bismuth doping for enhanced physical and electrochemical properties of CuO–ZnO thin films for complete degradation of Rifampicin and other antibiotics alongside organic dyes

In the current Study, undoped and bismuth doped CuO + ZnO coupled oxide thin films were meticulously deposited on glass substrates utilizing the spray pyrolysis technique. The effect of bismuth doping level in the structural, morphological, optical, electrical and electrochemical properties of these thin films were systematically investigated. X-ray diffraction patterns unequivocally confirmed the polycrystalline nature of the films, showcasing a combination of monoclinic CuO and hexagonal wurtzite ZnO phases. Furthermore, at a doping level of 8 %, the presence of the bismuth phase was observed, indicating its incorporation into the CuO–ZnO matrix. As the bismuth doping level increased, we observed a noticeable improvement in crystallinity and grain size. The distinctive characteristics of the developed thin films underscored a discernible enhancement in physical and electrochemical properties with the increase of bismuth doping level. Subsequently, The 8 % bismuth-doped CuO–ZnO thin films exhibit remarkable efficiency in degrading pharmaceutical compounds. Specifically, within a mere 2-h timeframe, these films demonstrate an exceptional degradation efficiency of 99 % towards Rifampicin, a widely used antibiotic. Moreover, their efficacy extends to other pharmaceutical pollutants, showcasing a significant degradation of 77 % for Ampicillin, an antibiotic commonly used to treat bacterial infections, and an even more substantial degradation of 90 % for Rhodamine B, a prominent dye compound. This underscores the promising potential of 8 % bismuth-doped CuO–ZnO thin films in addressing environmental and health-related challenges associated with pharmaceutical contaminants.

Cobalt-doped ZnO nanoparticles and PLD-deposited thin film forms: structure, optical properties and nature of magnetic anisotropy.

Cobalt-doped zinc oxide nanoparticles (NPs) were synthesized using a modified sol-gel method. Thereafter, the obtained powder was deposited on a Suprasil glass substrate by employing a pulsed laser deposition (PLD) technique. X-ray diffraction analysis with Rietveld refinement confirmed a hexagonal wurtzite ZnO phase belonging to the P63 mc space group for both samples in the NP and thin film forms. In particular, the thin film exhibited an intensive (002) XRD peak, indicating that it had a preferred c-axis orientation owing to the self-texturing mechanism. No segregated secondary phases were detected. The crystallite structure, morphology, and size were investigated using high-resolution transmission electron microscopy (HRTEM). To study the crystalline quality, structural disorder, and defects in the host lattice, we employed Raman spectroscopy. UV-vis-NIR spectroscopy was performed to confirm the nature of the Co-doped ZnO NP powder and the film. The chemical states of oxygen and zinc in the thin film sample were also investigated via X-ray photoelectron spectroscopy (XPS). The M-T curve could be successfully fitted using both the three-dimensional (3D) spin-wave model and Curie-Weiss law, confirming the mixed state existence of weak ferromagnetic (FM) and paramagnetic (PM) phases. Magnetic interaction was quantitatively studied and explained by polaronic percolation of bound magnetic polarons (BMPs). Analysis of magnetic symmetry of the topological antiferromagnetic as-deposited thin film using torque measurements was performed. Based on a phenomenological model, it was revealed that the structure gives rise to uniaxial magneto-crystalline anisotropy (UMA) with the magnetic easy axis parallel to the c-axis.

Annealing Effect on Structural, Optical and Electrophysical Properties of ZnSe Nanocrystals Synthesized into SiO2/Si Ion Track Template.

We report the results of synthesis of zinc selenide (ZnSe) nanocrystals into SiO2/Si track templates formed by irradiation with 200 MeV Xe ions up to a fluence of 107 ions/cm2. Zinc selenide nanocrystals were obtained by chemical deposition from the alkaline aqueous solution. Scanning electron microscopy, X-ray diffractometry, Raman and photoluminescence spectroscopy, and electrical measurements were used for characterization of synthesized ZnSe/SiO2nanoporous/Si nanocomposites. XRD data for as-deposited precipitates revealed the formation of ZnSe nanocrystals with cubic crystal structure, spatial syngony F-43m (216). According to non-empirical calculations using GGA-PBE and HSE06 functionals, ZnSe crystal is a direct-zone crystal with a minimum bandgap width of 2.36 eV and anisotropic electronic distribution. It was found that a thermal treatment of synthesized nanocomposites at 800 °C results in an increase in ZnSe nanocrystallites size as well as an increase in emission intensity of created precipitates in a broad UV-VIS spectra range. However, vacuum conditions of annealing still do not completely prevent the oxidation of zinc selenide, and a formation of hexagonal ZnO phase is registered in the annealed samples. The current-voltage characteristics of the synthesized nanocomposites proved to have n-type conductivity, as well as increased conductivity after annealing.

Investigation of the Structural, Optical, and Electrical Properties of ZnO/4‐Amino‐2‐Methylquinoline p–n Heterojunction by Spin‐Coating Method

A p–n heterojunction diode is fabricated using a p‐type 4‐amino‐2‐methylquinoline (C10H10N2) on an n‐type ZnO film and its structural, optical, and electrical properties are investigated. First, a ZnO thin film is prepared on an ITO substrate by spin coating. Subsequently, this ZnO film is coated with a C10H10N2 film using the same method. X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–vis spectroscopy, and current–voltage measurements are carried out on the prepared films. According to the XRD result, sharp peaks at 320.081, 340.488, and 360.548 are observed in the hexagonal phase of ZnO. At these angles, grain sizes of 15.308, 15.179, and 13.715 nm are calculated. The absorption peaks of electronic transitions π→π*, n→π*, and d→d* in the ZnO/C10H10N2 heterojunction film are observed. From the IV diagram, it can be seen that the heterojunction structure has a diode characteristic. From the IV data, the rectification factor is calculated to be 6.59 and its graph is drawn. With the Cheung method, ideality factor (n) = 2.87, series resistance (RS) = 1 MΩ, and shunt resistance (RSh) = 5 kΩ are found.

Blue-green emitting ZnS0.75O0.25:Ce3+,x%Tb3+ phosphor with tunable fluorescence lifetime

A series of ZnS0.75O0.25:0.1%Ce3+,x%Tb3+ phosphors were prepared by high temperature solid state reaction method. These phosphors exhibited two mixed phases consisting of hexagonal phase ZnS and hexagonal phase ZnO with the average particle size of 13.83 μm and emitted blue-green light. The luminescence mechanism consisted of Zn vacancy defects, the 5d1 → 2F5/2 radiative transitions of Ce3+, the 5D4 → 7F5 and 5D4 → 7F6 radiative transition of Tb3+ induced by the energy transfer of Ce3+ → Tb3+. An equation for the variation of the fluorescence lifetime of ZnS0.75O0.25:0.1%Ce3+,x%Tb3+ phosphors with concentration of Tb3+ fraction was obtained by exponential fitting. The short fluorescence lifetime could be tuned within the range of 113 μs to 550 μs with the increase of Tb3+ concentration, and the color was tunable from blue to blue-green, which is of important application in the field of high-energy particle detection.

Efficient rhodamine B dye photocatalytic degradation in aqueous media using novel ZnO nanomaterials co-doped with Ce and Dy

Water pollution caused by dyes and industrial wastewater poses a significant threat to ecosystems. The purification of such pollutants presents a major challenge. Photocatalysis based on semiconductor materials is a potential wastewater treatment process due to its safety and cost-effectiveness. In the present work, Zn1-2xCexDyxO (x = 0.01–0.05) semiconductors were prepared by the sol-gel auto-ignition method. The samples are denoted CDZO1, CDZO3, and CDZO5 for x = 0.01–0.05, respectively. The X-ray diffraction and Raman spectroscopy results revealed the formation of ZnO hexagonal phase wurtzite structure for all synthesized compositions. Different structural properties were determined. It was found that the lattice parameters and the unit cell volume increased, while the crystallite size diminished as x varied from 0.01 to 0.05. Transmission electron microscopy observations confirmed the formation of nanoparticles with the desired chemical compositions. The specific surface area (SSA) values are found to be 39.95 m2/g, 48.62 m2/g, and 51.36 m2/g for CDZO1, CDZO5, and CDZO5 samples, respectively. The reflectance spectra were recorded to examine the optical properties of the different nanoparticles. The values of the optical band gap were 3.221, 3.225, and 3.239 eV for CDZO1, CDZO3, and CDZO5 samples, respectively. In addition, the photocatalytic performance towards RhB dye degradation for the different samples was assessed. It was established that the CDZO3 sample with a moderate SSA value exhibited the superior photocatalytic performance among the other as-prepared samples wherein the percentage of degradation efficiency, and kinetic constant rate attained their maximum values of 98.22 % and 0.0521 min−1, respectively within 75 min. As per the obtained findings, it is evident that the Zn1-2xCexDyxO photocatalyst has prominent potential for use in the degradation of dyes and offers a useful route for impeding the recombination of electron-hole pairs of zinc oxide material.

Greenly synthesized zinc oxide nanoparticles: An efficient, cost-effective catalyst for dehydrogenation of formic acid and with improved antioxidant and phyto-toxic properties

Formic acid (FA) dehydrogenation is of particular industrial interest as a source of alternative fuels such as H2. However, the development of economical, highly efficient, and selective catalysts for this reaction is a challenging task. Most highly selective catalysts for the conversion of formic acid (FA)/sodium formate (SF) system into hydrogen are based on precious noble metals. Rendering their large-scale utilization more cumbersome and expensive. Therefore, it is of utmost importance to explore a facile and cost-effective strategy for the fabrication of a simple structured solid nano-catalyst with outstanding performance and selectivity for H2 generation without CO evolution from the FA/SF system. In the current study, a phenolic-enriched extract of wild olive leaves was employed for the synthesis of ZnO nanoparticles (ZnO@WOLE-NPs). TEM analysis revealed that the size of ZnO@WOLE nanoparticles was about33 nm. Zeta potential evaluation (38.39 ± 1.32 mV) demonstrated the significant stability of the nanoparticles. XRD analysis provided insights into the formation of hexagonal wurtzite phase ZnO nanoparticles. The reaction conditions were optimized. These resulting ZnO@WOLE-NPs showed extraordinarily high catalytic performance and about 80 % selectivity for H2 generation from the FA/SF system at 50 °C. A turn over frequency and activation energy values for dehydrogenation of FA were noted as 1519 h−1 and 32.1 kJ mol−1, respectively. The kinetics and thermodynamics of FA dehydrogenation were also determined. Furthermore, ZnO@WOLE-NPs exhibited potent antioxidant activity against hydroxyl, DPPH, superoxide, and peroxide radicals. Moreover, the synthesized nanoparticles demonstrated the highest seed germination of Okra seed at a concentration of 1.25 µg mL−1. Whereas, the highest shoot length and root length were observed at the concentration of 1 µg mL−1.

Antifungal Activity of ZnO Nanoparticles Synthesized from Eichhornia crassipes Extract for Construction Applications.

Fungal growth on construction materials in tropical climates can degrade aesthetics and manifestations on modern and historical sick buildings, affecting the health of their inhabitants. This study synthesized ZnO nanoparticles with enhanced antifungal properties using a precipitation method. Different concentrations (25%, 50%, and 100%) of Eichhornia crassipes aqueous extract were used with Zn(NO3)2·6H2O as the precursor to evaluate their spectroscopic, morphological, textural, and antifungal properties. X-ray diffraction confirmed the hexagonal wurtzite phase of ZnO with crystallite sizes up to 20 nm. Fourier-transform infrared spectroscopy identified absorption bands at 426, 503, and 567 cm-1 for ZnO-100, ZnO-50, and ZnO-25, respectively. Nitrogen physisorption indicated a type II isotherm with macropores and a fractal dimension coefficient near 2 across all concentrations. Polydispersity index analysis showed that ZnO-50 had a higher PDI, indicating a broader size distribution, while ZnO-25 and ZnO-100 exhibited lower PDI values, reflecting uniform and monodisperse particle sizes. FESEM observations revealed semi-spherical ZnO morphologies prone to agglomeration, particularly in ZnO-25. Antifungal tests highlighted ZnO-25 as the most effective, especially against Phoma sp. with an MFC/MIC ratio of 78 µg/mL. Poisoned plate assays demonstrated over 50% inhibition at 312 µg/mL for all tested fungi, outperforming commercial antifungals. The results indicate that ZnO NPs synthesized using E. crassipes extract effectively inhibit fungal growth on construction materials. This procedure offers a practical approach to improving the durability of building aesthetics and may contribute to reducing the health risks associated with exposure to fungal compounds.

Properties of spray pyrolysis deposited Zr-doped ZnO thin films and their UV sensing properties

This study investigated the characteristics of Zr-doped ZnO thin films with varying Zr doping concentrations. X-ray diffraction (XRD) analysis confirmed the presence of the ZnO hexagonal phase without any additional phases detected. The crystallite size was determined using Scherrer’s equation and Halder-Wagner equation, revealing distinct trends as the Zr content increased. The impact of Zr doping concentration on structural properties such as lattice parameters was also explored. Field emission scanning electron microscopy (FE-SEM) images indicated agglomeration, with a peak value observed at Zr-5 wt% of 175 nm that decreased at higher Zr contents. Optical properties exhibited minor variations with increasing Zr content, with the maximum band gap recorded at 3.28 eV for Zr-7 wt% and Zr-10 wt% films. Utilizing the Spitzer-Fan model, the high-frequency dielectric constant peaked at 14.26 for Zr-7 wt% films. Optical mobility displayed fluctuations with rising Zr content. Direct current (DC) conductivity results unveiled two donor levels in the deposited films, showcasing minimum activation energies of 0.23 and 0.165 eV for high and low-temperature ranges in the Zr-3 wt% film. Furthermore, the response to UV light illumination at a wavelength of 365 nm was examined, revealing notable changes in rise and decay times with varying Zr content.

Magnetic and optical properties of ZnO nanoparticles and nanorods synthesized by green chemistry

ZnO nanostructures have attracted considerable attention because of their physicochemical properties and applications as antibacterial agents, photocatalytic reactions for pollutant removal, and electronics. Hence, efficient production and knowledge of their properties under different synthesis conditions are essential. Biosynthesis has emerged as an excellent growth-directing method for synthesizing nanomaterials, representing a soft and cleaner alternative for their production. In this study, we synthesized different ZnO nanostructures using a soft chemistry method at different growth temperatures, from 200 to 800 °C every 200 °C. The crystalline structure was estudied by x-ray Diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HRTEM). The shape and size were studied by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM), which revealed a ZnO hexagonal phase with two shapes: nanoparticles (NPs) with irregular shapes and nanorods of different sizes. The optical properties were studied by Raman and UV-visible spectroscopy, and optical absorption measurements showed bandgap tuning of the produced nanostructures. Finally, the magnetic characteristics of the samples demonstrated magnetic anisotropy due to the preference for crystalline formation and the size of the nanoparticles. The magnetic interaction between the two types of NPs increased the diamagnetism associated with the nanorods.

Influence of sintering temperature on structural and optical properties of pure and Cl-doped ZnO nanoparticles

In this study, we conducted a detailed analysis of the sintering process of both pristine and 25 mg/g Cl-doped ZnO nanoparticles at varying temperatures to determine the optimum sintering temperature. Our findings revealed an optimal sintering temperature of 600 °C, resulting in higher phase purity (only hexagonal ZnO phase), smaller particle sizes of about 88–92 nm, and higher emission intensity for both pristine and Cl-doped ZnO nanoparticles. The band gap reduces from 3.63 eV to 3.20 for pristine and 3.63 eV to 3.10 for Cl-doped ZnO nanoparticles by increasing the sintering temperature from 200 °C to 1000 °C. The introduction of Cl in the ZnO lattice introduced a new defect level, having a broadband excitation band peaking at 374 nm. The luminescence of ZnO peaked at approximately 503 nm, which can be attributed to the transition from oxygen vacancies in the ZnO lattice. Notably, the emission intensity of the Cl-doped samples sintered at 600 °C was found to be 6.5 times higher than that of the pristine ones. Moreover, we found that the luminosity of ZnO:Cl nanoparticles was around 68% that of ZnS:Ag nanoparticles, which are typically used for radon detection and have similar efficiency to standard Lucas cells. Our preliminary findings suggest that Cl-doped ZnO nanoparticles sintered at 600 °C for 5 h could effectively develop radiation detectors, particularly for radon monitoring and related applications.

Amine functionalized graphene oxide decorated with ZnO-WO3 nanocomposites for remediation of organic dye from wastewater

Photocatalytic degradation is as an efficient technique to eradicate toxic chemical pollutants from contaminated water sources. However, the selectivity and photocatalytic activity are the challenging targets to explore the new photocatalysts. Therefore, our research goal is to develop a suitable photocatalyst to satisfy the recent photocatalytic degradation demand. In this work, amine functionalized graphene oxide (NH2-GO) supported heterojunction ternary novel nanocomposites (NH2-GO/ZnO-WO3) were prepared via simple solvothermal method. Structural and morphological investigations of the prepared composites are systematically observed by Field Emission Scanning Electron Spectroscopy (FE-SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet–Visible (UV–vis) Spectroscopy. FT-IR analysis confirmed the effective functionalization of amine on graphene oxide. The XRD results indicated that the prepared nanocomposites were free from any impurities and the binary composite (NH2-GO/ZnO) showed hexagonal wurtzite structure, whereas the ternary composite (NH2-GO/ZnO-WO3) exhibited mix crystal structure of monoclinic and hexagonal phase of WO3 and ZnO, respectively. The synthesized ternary photocatalyst (NH2-GO/ZnO-WO3) demonstrated superior photocatalytic efficiency towards various organic dyes such as cationic dye methylene blue (MB, 85.89%) and anionic dye methyl orange (MO, 60.98%) compared to binary photocatalyst (NH2-GO/ZnO) that showed only 52.28% of MB and 25.8% of MO dye degradation under UV light irradiation. The enhanced photocatalytic performance was mainly due to the low recombination rate of photogenerated electron-hole pair, narrow band gap, and large surface area of ternary composite. The presence of lone pair electrons in amino group provides a negative-charged surface composite resulting good interaction with cationic dye is the key to upgrade the photocatalytic performance. The ternary nanocomposite NH2-GO/ZnO-WO3 has the capacity to be a competent and acceptable photocatalyst for the photodegradation of organic dyes used in industries.

Influence of ZnSb2O6 Doping on Phase, Electrical and Dielectric Properties of ZnO Varistors

AbstractThe present investigation reports the variations of the microstructure and electrical properties due to a change in the ZnSb2O6 content of ZnO varistors. The impact of the ZnSb2O6 additive on both microstructure and electrical properties in ZnO varistors is studied via the X‐ray diffraction (XRD) and an impedance analyzer. Zn7Sb2O12 spinel phase and single hexagonal ZnO phase are detected in ZnO varistors with the addition of ZnSb2O6. The ZnO varistors with 5 mol% ZnSb2O6 have the highest nonlinear coefficient (43.2) and the lowest leakage current density (3.96 A cm−2). The resistivity of grain boundary ρgb increases continuously with the increasing content of ZnSb2O6 as demonstrated by impedance measurements. Additionally, low values of dielectric loss at high frequencies suggest a ZnO varistor doped with ZnSb2O6 is suitable for high frequency device applications.

Low temperature dielectric study and photoconductive analysis of ZnO/NiO composite material

The sol-gel process was used to synthesize a ZnO–NiO composite material in this study. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the material, which confirmed the existence of both ZnO nanoparticles and NiO sheets in the composite. The composite material contained two distinct crystalline phases, the face-centered cubic phase of NiO and the hexagonal phase of ZnO. The composite's average crystallite size was determined to be 19.0 nm. The particle size of the composite material was calculated to be ∼121 nm. The band edge emission at 393 nm (3.15 eV) was measured using photoluminescence (PL) spectroscopy. The PL spectrum revealed other emissions as well. The dielectric properties of the material were studied at low temperatures in the frequency range of 20 Hz to 1 MHz, and it was found to have a low dielectric dissipation at high frequencies, making it suitable for use in high frequency microwave devices. Impedance data was fitted using Z-View software with a fitting error of <5%. Impedance spectroscopy revealed that the composite material had two dielectric relaxation processes related to the bulk and the grain boundary. Analysis of frequency dependent ac conductivity revealed Overlapping large-polaron hopping (OLPH) is responsible conduction mechanism in our case indicated by variation of temperature (200–280 K) dependent parameter “s” with temperature. Photoconductivity studies showed that the composite material had enhanced electrical conductivity and photoconductivity compared to pure ZnO and NiO. This makes it a promising candidate for use in optoelectronic applications such as solar cells, optical switches, and photodetectors. The responsivity of composite (0.86 mA/Watt) is found to be 10 times greater than that of the responsivity of NiO (0.085 mA/Watt).

Farming of ZnO−SnO2 Nanocubes for Chemiresistive NO2 Gas Detection

AbstractThe ZnO−SnO2 nanocomposite has been synthesized using the simple and low‐cost co‐precipitation method. The physicochemical characterization of the prepared nanocomposites was carried out by using X‐ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE‐SEM), High‐resolution Transmission Electron Microscopy (HR‐TEM), Energy Dispersive X‐ray analysis (EDAX) and UV‐visible spectroscopy techniques. In XRD confirmed that, hexagonal wurtzite phase of ZnO with the tetragonal rutile phase of SnO2 was found to be in the pure form. The particle size of the ZnO−SnO2 nanocomposite was fund to be ~23 nm in size. The nano cubes like surface morphology of the ZnO−SnO2 nanocomposite has been investigated using FESEM. Based on this various characterization, the ZnO−SnO2 nanocomposite has been used for the development of the chemiresistive gas sensor application. The gas sensitivity is found to be 29.30 % for 100 ppm NO2 gas at 200 °C operating temperature. This work has been used for the development of gas sensor devices for practical application.

A Comprehensive Investigation of the Mechanical and Tribological Properties of AZO Transparent Conducting Oxide Thin Films Deposited by Medium Frequency Magnetron Sputtering.

This paper presents a detailed analysis of aluminium-doped zinc oxide (AZO) thin films and considers them a promising alternative to indium tin oxide in transparent electrodes. The study focusses on critical properties of AZO, including optical, electrical, and mechanical properties, with potential applications in displays, photovoltaic cells, and protective coatings. The deposited AZO thin films are characterised by excellent optical and electrical parameters, with transparency in the visible light range exceeding 80% and resistivity of 10-3 Ω·cm, which gives a high value of figure of merit of 63. Structural analysis confirms the nanocrystalline nature of as-deposited AZO thin films, featuring hexagonal ZnO, orthorhombic Al2O3, and cubic Al2ZnO4 phases. The study includes nanoindentation measurements, which reveal exceptional hardness (11.4 GPa) and reduced elastic modulus (98 GPa), exceeding typical values reported in the literature, highlighting their protective potential. Abrasion tests have shown extraordinary scratch resistance due to the lack of impact on topography and surface roughness up to 10,000 cycles. This comprehensive study demonstrated that as-deposited AZO thin films are multifunctional materials with exceptional optical, electrical, and mechanical properties. The findings open up possibilities for a variety of applications, especially in protective coatings, where the combination of hardness, scratch resistance, and transparency is both rare and valuable.