ZnO Elements Research Articles

Effect of Isopropanol on Optical Properties of Fe3O4/ZnO/Graphene Quantum Dots (GQDs) Nanocomposite

This study aims to investigate the impact of isopropanol on the optical properties of the Fe₃O₄/ZnO/GQDs nanocomposite. The synthesis of Fe₃O₄ and ZnO nanoparticles was conducted using the coprecipitation method, followed by the synthesis of GQDs using the hydrothermal method with varying concentrations of isopropanol. Subsequently, the Fe₃O₄/ZnO nanocomposite was combined with GQDs synthesized using the sonication method. The amalgamation of magnetic and luminescent materials holds promise for applications in the biomedical field, particularly in bioimaging. XRD data analysis revealed crystal structure alterations attributed to the incorporation of carbon elements in both ZnO and Fe₃O₄. The TEM results indicated a particle size of 16.2 nm for the Fe₃O₄/ZnO/GQDs nanocomposite with a 10 ml isopropanol variation. Identified phases from the XRD analysis include Fe₃O₄, ZnO, and GQDs. UV-Vis spectroscopy detected distinctive absorbance peaks at wavelengths of 323.7 nm, 333.0 nm, 329.9 nm, and 323.9 nm. Moreover, the energy gap exhibited an increase with escalating concentrations of isopropanol in the GQDs. Photoluminescence analysis yielded robust, broad emission bands characterized by orange and red luminescence.

Numerical Analysis of Electromagnetic Field, Heat and Thermal Stress of a Transmission Line Surge Arrester for Lightning Currents

The voltage across a 77‐kV‐class transmission line surge arrester (TLSA) and the heat in the TLSA have been computed using the finite‐difference time‐domain (FDTD) method for a lightning current having a magnitude of 50 kA, a risetime of 1 μs, and a half‐peak width of about 100 μs. The TLSA is represented with series‐connected‐nine ZnO elements, each of which has a length of 36 mm and a diameter of 32 mm. The ZnO element is represented with many 2 × 2 × 2 mm cubic cells, each of which has a nonlinear resistivity in each of the x‐, y‐, and z‐directions dependent on the electric field in each direction and the temperature in each cell. From the spatial and temporal distributions of FDTD‐computed heat in the TLSA, the spatial and temporal distributions of thermal stress in the TLSA have been computed using the finite‐element method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Intensity Loss of ZnO Coated on Fiber Optic

Macrobends are optical fiber structures suitable for detecting motion changes. This structure has been developed using single-mode fibers and a combination of single-mode and multimode fibers called hetero-core. In this study, a new macrobending structure was designed and developed by adding a nano-ZnO element to the fiber optic core based on Revolution 4.0. The addition of nanomaterial elements involves an etching process that uses harmful chemicals or high-cost laser technology. Therefore, hetero-core was applied in this study to replace the etching process. The ZnO-coated fiber optics with 10 (ZnO1), 20 (ZnO2), and 30 (ZnO3) times of dip coating were developed using the dip-coating method and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Sensitivity measurement was conducted with glued optical fiber in the form of bending using a tape with a bending dimension of 2.5 cm × 1.5 cm and a wavelength of 1,550 nm. Morphological characterization using SEM proves that nanoparticles are attached to the optical fiber, and the EDX characterization confirms that the nanoparticles are ZnO elements. Optical fiber sensor sensitivity using core sizes 9, 50–9–50, 50–9–50 (ZnO1), 50–9–50 (ZnO2), and 50–9–50 (ZnO3) achieved sensitivity values of 0.91, 1.61, 2.98, 3.34, and 3.51, respectively. This study successfully produced ZnO-coated optical fiber sensors with a hetero-core structure without performing the etching process and successfully increased the sensitivity of the sensors.

Facile synthesis of ZnO/CWO nanocomposite with brilliant enhanced optical response

In this research, novel zinc oxide/cadmium tungstate (ZnO/CWO) nanocomposite was prepared by a simple chemical method. The prepared nanocomposite was characterized for its structural and optical properties by different techniques. For the first time, the radiation response of prepared nanocomposite was studied using 241Am alpha source and ion beam induced luminescence (IBIL) measurement. Also, photocurrent transient responses of the prepared nanocomposite were recorded under Xe source radiation. ZnO/CWO nanocomposite exhibited strong light emission in the blue-green range at room temperature. Under alpha irradiation, the ZnO/CWO nanocomposite showed an excellent sensitivity when compared to pure ZnO or CWO. FESEM and TEM images showed a uniform distribution of spherical nanoparticles with an average particle size of 77 nm. XRD, XPS, and EDX results indicated characteristic peaks of ZnO, CWO, and related elements in the composite. Fourier transform infrared spectroscopy confirmed the presence of several groups in the nanocomposite. Investigations indicated that the optical quality of the ZnO/CWO nanocomposite was improved when compared with pure ZnO and CWO. According to obtained results, it is anticipated that ZnO/CWO nanocomposite would hold suitable potential for applications in optoelectronic devices and detection.

In-vitro evaluation and antibacterial activity of ZnO nanoparticles deposited on hydroxyapatite tablets by RF magnetron sputtering

RF magnetron sputtering was successfully applied in this study to deposit ZnO nanoparticles on hydroxyapatite tablets. Field emission scanning electron microscopy (FE-SEM) images showed the growth of ZnO nanoparticles with a grain size of ∼ 20 nm. Sedimentation occurred on the surface of samples after their immersion in simulated body fluid. Energy dispersive spectroscopy (EDS) analysis, confirmed the presence of Ca, P, Zn, and O elements, while MAP analysis indicated the uniform distribution of hydroxyapatite and ZnO elements. Atomic force microscopy (AFM) revealed lower surface roughness in the coated samples as compared to their uncoated counterparts. The root means square of roughness decreased with the ZnO coating. X-ray diffraction (XRD) results suggest the presence of the ZnO and hydroxyapatite phases. Antibacterial assay of ZnO-coated and uncoated tablets indicated the higher bioactivity of ZnO-coated tablets against E. coli. The atomic absorption spectrophotometry (AAS) and flame photometer results showed the release of Zn2+ and Ca2+ ions from the samples, respectively. During 14 days of immersion in simulated body fluid (SBF), Due to corrosion and destruction of the surface of the samples the Ca2+ concentration of ZnO-coated and uncoated samples, as well as the concentration of Zn2+ ions of ZnO-coated samples exhibited an increase.

Study on electron state density and optical properties of IIIA main group element-doped ZnO

The electronic structures and optical properties of pure ZnO and IIIA group elements Al-, Ga- and In-doped wurtzite ZnO are studied by using first-principles plane density of states pseudopotential method based on the density functional theory. Considering the difference between doped and undoped situation, the band structure, total/partial wave density and dielectric function, refractive index, reflectivity, absorption spectrum and loss function are investigated. The results show that all the three doped elements transform the pure ZnO into [Formula: see text]-type direct band gap semiconductor materials, and the band gap becomes smaller and smaller with the enhancement of the gold property of the doped elements. In addition, it is found by comparison that Al doping has the highest conductivity. In the visible light region, Ga-doped ZnO has a good transmittance and is an ideal transparent conductive material. In-doped ZnO has higher absorption rate and emission rate, and has a great application prospect in ultraviolet protection. The results have a positive reference value for IIIA main group elements in ZnO doping design.

Highly stretchable, breathable and negative resistance variation textile strain sensor with excellent mechanical stability for wearable electronics

In recent years, wearable and stretchable electronic devices have attracted great research interest and effort due to their promising applications in electronic skin, wearable health monitoring, human–machine interactions and so on. However, it still remains a great challenge to fabricate highly stretchable and wearable devices with excellent breathability, mechanical robustness and laundering durability. Herein, we fabricated a highly stretchable and breathable textile strain sensor based on conductive polyester fabric (CPF) with weft-knitted structure by chemically growing conductive and transparent Al-doped ZnO (AZO) element via atomic layer deposition (ALD). The CPF strain sensor demonstrates captivating performance, including high stretchability (up to 130%) and long-term stability (3000 cycles), as well as a distinct negative resistance variation with increasing strain owing to its weft-knitted structure. Most importantly, due to the formation of chemical interactions between textiles and AZO films during ALD process, the CPF strain sensor exhibits excellent mechanical robustness and laundering durability under reciprocating rubbing (50 kPa load pressure, 30 cycles), washing (500 r/min for 10 cycles, 200 min) and light fastness (accelerated light aging test for 7 days), thus allowing the fabrication of breathable and comfortable wearable sensor without elastomer encapsulation. Based on its admirable performances, the CPF strain sensor can be easily knitted or sewed on garments or attached on human skin directly for tracking both large and subtle human motions, revealing its numerous prospects in wearable electronics, intelligent robotics and other fields.

Enhanced photocatalytic activity of Ag and Fe2O3 co-doped ZnO nanostructure under visible light irradiation

ABSTRACTIn this study, undoped ZnO and Ag\\Fe2O3-doped ZnO nanostructures were successfully fabricated for photodegradation of Methyl Blue (MB) dye under visible light irradiation. XRD patterns confirm appeared of Ag\\Fe2O3 phases and polycrystalline structure of ZnO with a wurtzite hexagonal phase. EDX spectra compatible with XRD results and confirm appeared peaks energy of Ag, Fe2O3, ZnO elements. FESEM results showed agglomeration of irregularly shaped nanoparticles (NPs), decreasing with increasing doped concentration which leads to appearing of Nanorod, Nanosheet, and cluster of small NPs. UV-Visible spectra revealed Ag and Fe2O3 doped leads to shift in ZnO spectra band and increased absorption in a visible light region. The photocatalytic activity showed significantly enhanced with degradation percentages 96.6%, 95.1%, 92.6%, and 92.7% for doped ZnO, as compared to 73.8% for undoped ZnO. This marked enhanced in photocatalytic activity attribute to increased hydrophilicity, surface area which can improve separation of charge carriers, and photogenerated efficiency.

Effect of Mg doping on structural, morphological, optical and thermal properties of ZnO nanoparticles

Doping of group II elements in ZnO is an efficient way to enhance the optical properties of ZnO nanoparticles. For this purpose, Zn1-xMgxO nanoparticles (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) are synthesized using co-precipitation technique. Effect of ‘Mg’ doping on structural, morphological, optical and thermal properties of ZnO nanoparticles is investigated. XRD results verify that synthesized nanoparticles are poly-crystalline with typical hexagonal wurtzite structure and possess no other impurity or dopant phases. Crystallite size is increased with the increase in ‘Mg’ content. SEM analysis reveals that polyhedral grains are aggregated with the increase in doping concentration of Mg. For the highest dopant concentration, surface morphology is entirely changed with the formation of nanowires. Optical band gap energy of Mg-doped ZnO nanoparticles is greater than that of pristine ZnO nanoparticles. The blue shift in band gap is observed with Mg content x ≤ 0.04, followed by red shift for higher Mg content. The decrease in phase transition and increase in decomposition temperature for Mg-doped ZnO nanoparticles suggest their thermal stability. Tailoring of band gap makes ZnO nanoparticles a promising material for photocatalysis, optoelectronic and display devices.

Structural, chemical and mechanical properties of phosphate glass fibers

Phosphate glasses with the compositions of (53-x)P2O5-11K2O-25CaO-11MgO-X; (X: ZnO, CoO, Fe2O3) were prepared and subsequently transformed into fibers by a monofilament extruder. The compositions and amorphous nature of the glasses were confirmed by XRD, Raman and infrared spectroscopies. The SEM shows that the elaborated fibers at a spinning speed of 500 m/min have a diameter of 17 μm. The degradation study in aqueous solution at 37 °C showed a decrease of 99% in degradation rate with the addition of ZnO, CoO and Fe2O3 elements. This confirmed that the chemical durability of the glasses had increased. DSC showed an increase in Tg values by addition ZnO, CoO and Fe2O3 contents. The tensile properties show that the phosphate glass fibers have good mechanical properties, the highest tensile strength obtained is 1321 ± 50 MPa. The density measured revealed an increase from 2.54 to 2.7 g.cm−3.

Preparation and characterization of GO-ZnO nanocomposite for UV detection application

In this research, graphene oxide-zinc oxide nanocomposite film (GO-ZnO) was prepared by cost-effective solvothermal, spin-spray coating methods and studied for its UV sensing properties. I-V curve of prepared nanocomposite was recorded under illumination of an ultraviolet lamp. SEM and TEM images indicated the layer formation of GO and showed a uniform distribution of ZnO nanoparticles into GO nanosheets. XRD, Raman and EDX results indicated characteristic peaks of GO, ZnO and related elements in composite. For the first time based on ion beam induced luminescence (IBIL) study, GO-ZnO nanocomposite exhibited strong light emission in the UV-blue range at room temperature. The photoluminescence and IBIL investigations indicated that the optical quality of the GO-ZnO nanocomposite was improved compared with pure ZnO. The sensitivity in GO-ZnO composite and ZnO sample for VBias = 5 v was obtained about 24 and 3 respectively. The GO-ZnO nanocomposite with ZnO particle size of 20–30 nm showed higher sensitivity and faster response time as compared to bare ZnO. According to obtained results, it is anticipated that GO-ZnO nanocomposite would hold suitable potential for application in UV–Vis optoelectronic devices.

Defect stabilization and reverse annealing in ZnO implanted with nitrogen at room and cryogenic temperature

Despite the fact that nitrogen is a potential acceptor dopant and one of the most studied elements in ZnO, lacking understanding of associated defects and their thermal evolution limits realization of reliable p-type doping of ZnO. Here, we use ion implantation to introduce N at room temperature (RT) and 15 K in ZnO samples with/without a pre-existing buried disorder layer formed by Ag ion bombardment aligned along the [0001] direction. The buried layer contains a high concentration of extended defects, which act as traps for migrating point defects. Channeling analysis shows that reverse annealing occurs in all the N implanted samples during post-implant heat treatment above 600 °C with strong non-linear additive damage accumulation in the co-implanted samples. The reverse annealing effect is less stable in the RT co-implanted sample and the data suggest that a high local concentration of intrinsic point defects, like Zn interstitials, promotes the stability of the N-defect clusters responsible for the reverse annealing. This suggestion is also corroborated by enhanced and defect-mediated Ag outdiffusion at 1100 °C in the RT co-implanted samples.

アルミニウム微量添加が酸化亜鉛（ZnO）バリスタ素子特性に与える影響

It is well known that aluminum doping is very effective for improving the Voltage-Current (V-I) characteristics of ZnO varistor elements comprising Bismuth oxide and Antimony oxide. Although it is established that the presence of aluminum lowers the resistance of ZnO grains by valence control, in this study, it is proposed that the homogeneity of micro structure of ZnO elements is more effective for improvement of V-I characteristics. The relationship between electrical characteristics and microstructure at different aluminum doping levels and sintering temperatures is shown with V-I characteristics, SEM observation and capacitance measurement of ZnO elements. As the effect of Al doping, it was found that moderation of ZnO grain growth causes the homogeneity of microstructure of ZnO varistors. In detail, reduction of the volume ratio of high resistive parts like thicker grain boundaries and multiple point between ZnO grains leads to excellent non-ohmic V-I characteristics. In addition, it is suggested that the tunnel effect by thinner grain boundaries is important as the mechanisms of improvement of V-I characteristics.

Estimation of Critical Resistive Leakage Current of polymer housed ZnO surge arrester by electro-thermal modelling

In this study, a MATLAB/Simulink software based electro-thermal model of the polymer housed, gapless, 60kV ZnO surge arrester is used for estimating the ‘ Critical Resistive Leakage Current (CRLC)’. The electrical model is obtained by conducting experiments on a representative ZnO element at various voltages and temperatures which yields voltage–current–temperature (V–I–T) and power loss–voltage–temperature (P–V–T) characteristics. The thermal model represents the thermal properties of the arrester components as an electrical analogous circuit made of resistance & capacitance. The power loss calculated by the electrical model is the input to the thermal model. The electrical and thermal models run for numerous iterations until the arrester goes to thermal runaway or until it reaches a stable element operating temperature. The electro-thermal model is used to determine the two intersection points (stable operating point and the thermal instability point) of the power input and heat loss curves. The authors have proposed a new criteria based on detection of occurrence of the highest segmental slope inbetween the lower stable operating point and upper instability point on the power input curve (P–V–T characteristics) to estimate the CRLC. In order to sensitise the maintenance personnel about the level of deterioration and imminent failure of the arrester in the near future a warning in the form of the Observation Current (OBCUR) is also proposed. The easy to follow procedures for estimating the CRLC and OBCUR and the results obtained for two different arresters (of two different manufacturers) are presented in this paper.

Zn precipitation and Li depletion in Zn implanted ZnO

Ion implantation of Zn substituting elements in ZnO has been shown to result in a dramatic Li depletion of several microns in hydrothermally grown ZnO. This has been ascribed to a burst of mobile Zn interstials. In this study, we seek to understand the reason behind this interstitial mediated transient enhanced diffusion in Li-containing ZnO samples after Zn implantation. ZnO wafers were implanted with Zn to two doses, 5 × 1015 cm−2 and 1 × 1017 cm−2. Secondary ion mass spectrometry was carried out to profile the Li depletion depth for different annealing temperatures between 600 and 800 °C. The 800 °C annealing had the most significant Li depletion of close to 60 μm. Transmission electron microscopy (TEM) was carried out in selected samples to identify the reason behind the Li depletion. In particular, TEM investigations of samples annealed at 750 °C show significant Zn precipitation just below the depth of the projected range of the implanted ions. We propose that the Zn precipitation is indicative of Zn supersaturation. Both the Li depletion and Zn precipitation are competing synchronous processes aimed at reducing the excess Zn interstitials.

Influence of doping group I elements on structural, optical and magnetic properties of nanocrystalline ZnO

Pure ZnO and group-I elements doped ZnO nanocrystals were synthesized by solution combustion method. The XRD analysis reveals that all the ZnO doped nanocrystals have hexagonal wurtzite crystal structure. Scanning electron microscopy reveals the growth of rod like structure for Na doped sample. The UV–Vis absorption results show that the band gap of ZnO doped nanocrystals is red shifted with decrease in crystallite size. A sharp peak at 434 cm−1 was observed in Raman spectra which correspond to the high frequency E2 mode of ZnO. Photoluminescence properties of pure and group-I elements doped ZnO nanocrystallites have strong blue emission at 421 nm. The peak positions were found to be almost same even after the addition of alkali metal ions owing to the variation in the nanostructure and difference in ionic radii. Vibrating sample magnetometer studies show that the doping of group-I elements show ferromagnetic behavior compared to pure ZnO samples which are paramagnetic. Our investigations make, hence, useful contributions to nano-photonics, luminescence and optoelectronic devices.

Energy absorption capacity of a 500 kV surge arrester for direct and multiple lightning strokes

Damage to 500 kV surge arresters occurred due to direct and multiple lightning strokes. The present paper initially analyzes the mechanism of how the surge arresters were damaged based on the accident investigative results and evaluates the energy absorption capacity of existing surge arresters by analyzing the energy absorbed when the surge arresters were damaged. Consequently, the damage was confirmed as attributable by the crack of ZnO elements due to the thermal stress sustained when absorbing the energy of direct and multiple lightning strokes. The damage energy was estimated at about 5.4 MJ. Subsequently, based on the lightning observation data according to the lightning location system and the lightning outage rate of transmission lines, the standard lightning-stroke conditions were determined, the required energy absorption capacity of the surge arresters was analyzed and determined to be less than 5.3 MJ. Although the energy absorbed in the above damage cases exceeds this required energy absorption capacity, it is still considered within the variable range of lightning events. Consequently, existing surge arresters have the required energy absorption capacity and the cases involving damage to surge arresters are considered extremely rare.

Electrical Properties of CZO Films Prepared by Ultrasonic Spray Pyrolysis.

CuZnO (CZO) films have attracted increasing amounts of attention due to their promising potential applications in semiconductor devices. ZnO shows n-type conductivity, and attempts have been made to dope several elements in ZnO to improve the electrical properties. This study investigated the electrical property transitions of CZO films and determined the copper concentration at which the conductivity of CZO films will change from n-type to p-type. In this study, CZO films were fabricated by ultrasonic spray pyrolysis with copper acetate, zinc acetate, and ammonium acetate precursor solution. The concentrations of Cu ions in the CZO films were controlled by the concentration ratios of copper acetate to zinc acetate in the precursor solutions. In addition, these samples were analyzed by Hall effect measurements, X-ray diffraction, transmittance measurements, and photoluminescence measurements. The results show that the conductivity of the CZO film changes from n-type to p-type when the copper ion concentration in the film is 5%.

Investigation into the Metal Oxide Surge Arrestors' Failures

Metal oxide surge arrestors (MOSA) are commonly used in the electrical power system to protect the insulation from the damaging effect of lightning. This paper presents the damage characteristics and possible root cause of two exploded ZnO type arrestors. Both failures were not caused by lightning surge. They had degraded due to moisture ingress, leading to contamination and corrosion, accelerating thermal runaway effect in the ZnO elements and eventually caused early voltage breakdown under normal operating voltage. This indicated an inadequacy in the sealing components.

Structural, optical, electrical and thermal properties of zinc oxide thin films by chemical spray pyrolysis

Thin films of highly textured ZnO are synthesized by simple chemical spray pyrolysis onto corning glass substrates in aqueous medium. The influence of solution concentration onto photoelectrochemical, structural, morphological, compositional, optical, electrical and thermal properties have been investigated. Structural analysis shows the hexagonal (wurtzite) crystal structure. Electron–phonon-coupling in ZnO films has analyzed using Raman spectroscopy. The chemical composition and valence states of constituent elements in ZnO are analyzed by X-ray photoelectron spectroscopy. The SEM and AFM micrographs depict the films are compact and homogeneous (hexagonal platelets nanostructures) with varying grain sizes (average grain size ∼50–150nm). The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films.