Increase In ZnO Concentration Research Articles

The Effect of Zinc Oxide on DLP Hybrid Composite Manufacturability and Mechanical-Chemical Resistance.

The widespread use of epoxy resin (ER) in industry, owing to its excellent properties, aligns with the global shift toward greener resources and energy-efficient solutions, where utilizing metal oxides in 3D printed polymer parts can offer extended functionalities across various industries. ZnO concentrations in polyurethane acrylate composites impacted adhesion and thickness of DLP samples, with 1 wt.% achieving a thickness of 3.99 ± 0.16 mm, closest to the target thickness of 4 mm, while 0.5 wt.% ZnO samples exhibited the lowest deviation in average thickness (±0.03 mm). Tensile stress in digital light processed (DLP) composites with ZnO remained consistent, ranging from 23.29 MPa (1 wt.%) to 25.93 MPa (0.5 wt.%), with an increase in ZnO concentration causing a reduction in tensile stress to 24.04 MPa and a decrease in the elastic modulus to 2001 MPa at 2 wt.% ZnO. The produced DLP samples, with their good corrosion resistance in alkaline environments, are well-suited for applications as protective coatings on tank walls. Customized DLP techniques can enable their effective use as structural or functional elements, such as in Portland cement concrete walls, floors and ceilings for enhanced durability and performance.

Detecting and shielding properties of Ce3+-doped zinc–gadolinium-fluoroborate glasses for X-ray and proton radiation

Zinc-gadolinium-fluoroborate glasses doped with cerium fluoride (CeF3) were successfully fabricated to detect and shield X-ray and proton radiation. The doped glasses were studied at varying ZnO concentrations to investigate their properties, including density, transmittance, photoluminescence, and the oxidation states of dopants The glasses were tested for their sensitivity to detect X-ray and proton radiation, and calculations of the half-value layer and proton range were used to investigate their shielding properties. The results showed that an increase in ZnO concentrations induced a higher glass density and shifted the absorption edge to a longer wavelength (redshift) in the optical transmittance spectra. The cerium dopant mainly formed the Ce3+ oxidation state, resulting in a single broad band emission due to the 5d→4f transition of Ce3+ ions. The luminescence behavior of the doped glasses under x-ray irradiation showed a single broad emission at 375 nm. In contrast, under proton irradiation, the single broad emission shifted to a longer wavelength at 400 nm. The increase in ZnO concentration decreased light emission when exposed to x-rays and protons. The results also demonstrated that increasing ZnO concentrations improved the shielding properties of the glasses. We found that the glass with a 25 mol% ZnO concentration revealed a half-value layer of the 100 keV photon energy equal to 0.116 ± 0.001 cm, and a 70 MeV proton energy penetrated the maximum range in the glass at 1.308 ± 0.019 cm. We concluded that ZnO could be used to control the fraction between Ce3+ and Ce4+ ions in the cerium ions of the CeF3-doped glasses.

Mechanical Property, Thermal Stability and BioDegradability Studies on PLA based Bio-Nanocomposites derived from Agricultural Residues

Looking at the environmental hazards being posed by indiscriminate use of synthetic plastics, abundant research is being done to explore various bio-degradable polymers. In the present study, Cellulose Nano Fibers (CNFs) were extracted from Pineapple Crown using mechano chemical treatment, PLA was synthesized by Simultaneous Saccharification and Fermentation using cellulase enzyme on Acacia Arabica as substrate. Further, ZnO nanoparticles were synthesized by using different precursors. The biocomposite sheets of PLA, PLA+ 5%-20% CNFs, PLA+5% ZnO+5-20 % CNFs and PLA+10% ZnO+5-20 % CNFs were solvent casted. Microbial efficacy test was done using E.coli and with inclusion of ZnO nanoparticles the microbial resistance has increased. Noteworthy vibration band of the sheets were observed in the wavelength range of 3700 to 2800 cm-1 from the FTIR analysis, which shows that there is only a physical interaction rather than chemical. The crystallinity increased for initial concentration, but was similar to the neat PLA. Significant increase in tensile strength and maximum elongation at break was observed in PLA + 5% ZnO + 10% CNFs sheet. Sheets were allowed to degrade naturally and significant weight loss was observed after 120 days with maximum reduction of 38.4 %. Morphological analysis through SEM revealed the uniform distribution of fillers in the polymer matrix. TGA studies have shown that the degradation temperatures were in the range of 320-405oC. The thermal stability decreased with the increase in ZnO concentration. The results have shown a promising and sustainable use in various applications in view of microbial resistance and bio-degradability.

Effect of acceptor concentration in the FRET controlled photoluminescence of PMMA-ZnO nanocomposite for the application of PLED device

Luminescent PMMA-ZnO nanocomposites are synthesised through bulk polymerization of MMA in presence of ex-situ prepared ZnO nanoplates. Variation of ZnO concentration affects the optical properties of the composite. Introduction of ZnO in the PMMA matrix makes the composite as semiconducting in nature by creating a lower energy gap in the composite. Again Förster resonance energy transfer (FRET) between PMMA (donor) to ZnO (acceptor) enhances emission of ZnO significantly. But the enhanced emission decreases with increase in ZnO concentration, i.e. the emission intensity of PMMA-ZnO nanocomposite shows an increasing trend with decrease in the content of ZnO. The energy transfer efficiency varies from 97% to 52% when the concentration of ZnO varies from 10 wt% to 30 wt%. The Photoluminescence quantum efficiency of the composite showing highest emission is calculated and found to be 74%. Corresponding theoretically calculated electroluminescence quantum efficiency is 4% at an operating voltage of 3.1 V assuming all the injected charge carriers can generate singlet exciton if the composite showing highest emission is used as an emissive layer in PLED.

Thermo-Hydraulic Performance of a Lubricant Containing Zinc Oxide Nano-Particles: A Two-Phase oil

Abstract The first goal is to propose a two-variable equation for predicting the viscosity of zinc oxide-SAE50 nano-lubricant. In this way, the curve fitting was applied on laboratory data. Laboratory data have been reported in the temperatures ranging from 25 to 50 °C of and the nano-particles concentrations ranging from 0.125% to 1.5% previously. The presence of nano-particles leads to intensify the pressure descent and heat transfer, simultaneously. Therefore, the second goal was to evaluate the influence of nano-particles on the pressure descent and heat transfer. To achieve this goal, using existing relationships, heat transfer and pressure drop were estimated using nano-lubricant properties. Findings showed that the pressure drop ratio and coefficient of heat transfer augmented with an increase in ZnO concentration. Furthermore, calculations revealed that thermal performance factor enhances with increasing temperature and had a maximum value at volume concentration of 1%. It means that volume concentration of 1% is an optimal point in the preparation of this nano-lubricant.

Enhanced Solar Light Driven Photocatalytic Degradation of Organic Dye Using Solution Combustion Synthesized CeO2-ZnO Nanocomposites

CeO2 and CeO2-ZnO nanocomposites were synthesized by the solution combustion method. Cerium/Zinc nitrates and sucrose were used as an oxidizer and fuel, respectively. Structural, morphological and optical properties were studied using x-ray diffraction (XRD), a field emission scanning electron microscope (FESEM) and ultra violet–visible absorption spectroscopy. XRD results show that the prepared CeO2 has cubic structure, whereas the CeO2-ZnO composite has both cubic and hexagonal structure. The particle size was found to decrease from 11 nm to 7 nm on increasing the fraction of ZnO in CeO2-ZnO nanocomposites. Optical characterisation showed that the band gap of pristine CeO2 and CeO2-ZnO nanocomposites red shifted from 3.02 eV to 2.91 eV. FESEM analysis revealed porous-like morphology of CeO2-ZnO nanocomposites. Pristine CeO2 and CeO2-ZnO nanocomposites with ratios of 1:0.33, 1:0.5 and 1:1 were evaluated for their photocatalytic activity against the degradation of methylene blue (MB) under solar light for 90 min. The degradation efficiency was 51.1% for pristine CeO2 and CeO2-ZnO (1:1) shows more degradation efficiency (99.9%), when compared to other ratios. Photocatalytic degradation efficiency was increased with increase in ZnO concentration in nanocomposites. This is due to reduced bandgap and less recombination of photo-generated charge carriers.

Concentration-dependent behaviors of ZnO-reinforced PVA–ZnO nanocomposites as electron transport materials for OLED application

The laboratory synthesis of pure PVA and PVA–ZnO nanocomposites of varying concentrations was synthesized via co-precipitation and in situ techniques, respectively. The formation of PVA and PVA–ZnO nanocomposites and the corresponding changes in their structural properties were examined using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic techniques. The FESEM images displayed regular distribution of ZnO nanowires in PVA matrix. The UV–Vis absorption spectra showed that the direct band gap (E g) decreased with the increase in ZnO concentration. The UV–Vis spectra also indicated the shifting towards blue–green region for higher ZnO concentrations. The optimized direct band gap was estimated around 2.985 eV duly associated with the p-type conductivity. The photoluminescence (PL) study revealed optimum intensity for 5:2 ratio of PVA:ZnO nanocomposites and blue emission (470 nm) varied with the increase in ZnO concentration. The atomic force microscopy (AFM) study showed that RMS roughness of the nanocomposites increased with the increase in ZnO concentration. The enhanced current density (~ 237.83%) in the visible region and reduced optical band gap with relatively higher electron–hole non-radiative recombination rate was in good agreement with the data for electron transport layer material for organic light emitting diode (OLED) application.

Organic-inorganic hybrid nanomaterials for advanced light dependent resistors

We report the photoconduction behaviour of hybrid organic (polypyrrole) - inorganic (ZnO) nanostructures, synthesized by the surfactant mediated solution based chemical method at room temperature, for the energy saving light dependent resistor (LDR) applications. The formation of organic-inorganic hybrid nanostructures is confirmed by the combination of high resolution transmission electron microscopy and scanning electron microscopy, which revealed creation of cubical shaped wurtzite ZnO nanoparticles with different preferential orientations and transformation of clip-like nanofibres form of pure polypyrrole (PPy) into worm-like nanoribbons having embedded ZnO nanoparticles in it. Given p-type nature of PPy and n-type nature of ZnO, the embedment of ZnO nanoparticles in PPy is expected to create several localized discrete p-n junctions, which is why Raman spectroscopic results reveal the change in molecular structure of PPy due to its nanoscale interaction with ZnO. The photoresponse of PPy is found to continuously enhance from ∼4.5 to 10.7% with increase in ZnO concentration from 0 to 10% at the constant illumination intensity of 100 mW/cm2. The improved photoresponse can be attributed to the formation of localized p-n junctions (p-type PPy/n-type ZnO) in the structure. The photoresponse of PPy and its nanocomposites also increases with increase in illumination intensity from 30 to 100 mW/cm2, which is attributed to the increased number of photo-generated electron-hole pairs.

Morphological, structural, dielectric and electrical properties of PEO–ZnO nanodielectric films

The morphological, structural, dielectric and electrical properties of aqueous solution-cast prepared poly(ethylene oxide)–zinc oxide (PEO–ZnO) nanocomposite films have been investigated as a function of ZnO nanoparticle concentrations up to 5 wt%. Scanning electron microscopy (SEM) images of these films show that the morphology of pristine PEO aggregated spherulites changes into fluffy, voluminous and highly porous with dispersion of ZnO nanoparticles into the PEO matrix. X-ray diffraction (XRD) study confirms that the crystalline phase of PEO greatly reduces at 1 wt% ZnO, and it again increases gradually with further increase of ZnO concentration. The dielectric relaxation spectroscopy (DRS) over the frequency range 20 Hz–1 MHz reveals that the real part of complex dielectric permittivity at audio frequencies decreases non-linearly whereas it remains almost constant at radio frequencies for these polymeric nanocomposites. Dispersion of nanosize ZnO particles into the PEO matrix reduces the values of dielectric permittivity which also exhibits a correlation with the dispersivity of ZnO nanoparticles. The relaxation peaks observed in the dielectric loss tangent and electric modulus spectra reveal that the electrostatic interactions of nanoscale ZnO particles with the ethylene oxide functional dipolar group of PEO monomer units decrease the local chain segmental dynamics of the polymer. Real part of ac conductivity spectra of these films have been analyzed by power law fit over the audio and radio frequency regions, respectively, and the obtained dc conductivity values for these regions differ by more than two orders of magnitude. The temperature dependent relaxation time and dc conductivity values of the nanodielectric material obey the Arrhenius relation of activation energies and confirm a correlation between dc conductivity and PEO chain segmental motion which is exactly identical to the characteristics of solid polymer electrolytes. Results imply that these nanocomposite materials can serve as low permittivity flexible nanodielectric for radio frequency microelectronic devices and also as electrical insulator for audio frequency operating conventional devices in addition to their suitability in preparation of solid polymer electrolytes.

Influence of ZnO concentration on the optical and photocatalytic properties of Ni-doped ZnS/ZnO nanocomposite

Photocatalysts consisting of nickel-doped ZnS/ZnO core shell nanocomposites with varying concentrations of ZnO was synthesized through chemical precipitation method. The catalyst was deployed in photocatalytic degradation of indigo carmine dye as a model organic pollutant. Characterization of the samples was achieved through the use of X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, UV–vis spectroscopy and energy dispersive spectroscopy. The composites consist of wurtzite ZnO phase deposited on cubic ZnS. Optical absorption, crystallite sizes and photocatalytic degradation efficiency increased with increasing ZnO concentration. Bandgap values of ZnS also decreased appreciably with increase in ZnO concentration. Ni-doped ZnS/(0.5 M ZnO) was identified as the most efficient catalyst with 91% dye degradation efficiency at a rate of 15.38 × 10−3 min−1 in 180 min. Meanwhile, the pristine ZnS degraded 25% of the dye at the rate of 1.53 × 10−3 min−1 within the same time. The Ni-doped Zns/(0.5 M ZnO) was used to degrade the dye on the basis of influence of factors such as solution temperature, hydrogen peroxide (H2O2) and ethanol contents. Dye degradation increased with increase in temperature, but decreased with ethanol content. H2O2 content initially caused enhanced dye degradation but the efficiency decreased with higher H2O2 content.

Structural, dielectric, and impedance study of ZnO-doped barium zirconium titanate (BZT) ceramics

Polycrystalline lead-free BaZr0.15Ti0.85O3 ceramics doped with ZnO (0 ≤ x ≤ 2 wt%) were produced via mixed oxide solid-state reaction method. X-ray diffraction confirmed the presence of a single phase having tetragonal symmetry and having space group P4 mm. Scanning electron microscopy confirmed an increase in the density of microstructure and enlargement of grains with increase in ZnO concentration. Complex impedance spectroscopy revealed non-Debye type relaxation phenomenon. It was observed that an increase in the resistance of grain boundaries and decrease in that of grain interior (bulk) occurred with an increase in temperature. Relaxation time decreased with increase in temperature for both grain boundaries and grain interior. Understandings obtained from this work might be helpful in engineering the microstructure of BZT-based ceramics for useful applications.

Eu-doped ZnO–HfO2 hybrid nanocrystal-embedded low-loss glass-ceramic waveguides

We report on the sol–gel fabrication, using a dip-coating technique, of low-loss Eu-doped 70SiO2 – HfO2–xZnO (x = 2, 5, 7 and 10 mol%) ternary glass-ceramic planar waveguides. Transmission electron microscopy and grazing incident x-ray diffraction experiments confirm the controlled growth of hybrid nanocrystals with an average size of 3 nm–25 nm, composed of ZnO encapsulated by a thin layer of nanocrystalline HfO2, with an increase of ZnO concentration from x = 2 mol% to 10 mol% in the SiO2–HfO2 composite matrix. The effect of crystallization on the local environment of Eu ions, doped in the ZnO–HfO2 hybrid nanocrystal-embedded glass-ceramic matrix, is studied using photoluminescence spectra, wherein an intense mixed-valence state (divalent as well as trivalent) emission of Eu ions is observed. The existence of Eu2+ and Eu3+ in the SiO2–HfO2–ZnO ternary matrix is confirmed by x-ray photoelectron spectroscopy. Importantly, the Eu-doped ternary waveguides exhibit low propagation losses (0.3 ± 0.2 dB cm–1 at 632.8 nm) and optical transparency in the visible region of the electromagnetic spectrum, which makes ZnO–HfO2 nanocrystal-embedded SiO2–HfO2–ZnO waveguides a viable candidate for the development of on-chip, active, integrated optical devices.

Impact of ZnO substitution on magnetic response and microwave absorption capability of strontium-natural nanoferrites

Ferrite being a compound derived from iron oxides including magnetite and hematite possesses similar properties as ceramics which are hard and brittle. Certainly, the mounting demand for electronics has been a major factor driving the exponential growth of ferrite based materials. ZnO doped strontium-natural nanoferrites of composition (80−x)Fe2O3:xZnO:20SrCO3, where x=0, 10, 20mol% are synthesized and sintered via the solid state reaction scheme. Samples are characterized by SEM, XRD, VSM, and VNA measurements to determine the impact of ZnO contents’ variation on the surface morphology, structure, magnetic and microwave absorption properties. The Nicolson–Ross–Weir method is applied to evaluate samples’ reflection loss. The average grain size of the strontium ferrite is found to reduce with the increase in ZnO concentration. Materials sintered at 1100°C without ZnO incorporation are composed of hexagonal SrFe12O19. Meanwhile, the addition of ZnO produces cubic ZnFe2O4 and SrFeO2 phases. Insertion of ZnO results in reduction of magnetic parameters and reflection loss. Furthermore, the anisotropy magnetic field of strontium natural ferrites displays a rapid drop from 350kA/m to 79.6kA/m with the increase in ZnO. Strontium ferrite containing 20mol% of ZnO exhibits superior microwave absorption with reflection loss within −45dB to −55.94dB in the frequency range of 7–13GHz. This facilely synthesized a new class of materials which is believed to be economically promising for microwave absorption applications in the GHz range.

Enhancement of poly(phenyl sulfone) membranes with ZnO nanoparticles

ABSTRACT In this work, poly(phenyl sulfone) (PPSU) membranes were prepared by diffusion-induced phase inversion method in N-methyl-pyrrolidone using different concentrations of ZnO nanoparticles as additives. The main objective of this work is to evaluate the performance of the PPSU membranes with ZnO nanoparticles. The concentrations of ZnO were 0, 0.01, 0.015, 0.02, 0.025, and 0.03 wt.%. The effect of the ZnO nanoparticles on the characteristics of PPSU membranes was investigated with scanning electron microscopy and atomic force microscopy observations, contact angle measurement, nanofiltration experiments, and observations of solute rejection. It was found that the cross-section structure of the membrane changes from a finger-like and sponge-like structure formed near the support and top layers, respectively, to fully sponge-like structure with increase of ZnO concentration up to 0.025 wt.%. The mean pore size and mean roughness of the PPSU/ZnO membranes increased with the ZnO concentration. The membrane hydrophilicity increases due to the addition of ZnO nanoparticles. The flux of the PPSU membranes with 0.025 wt.% ZnO as additives enhanced from 76 to 107 (L m−2 h−1 bar−1) with no significant change in solute rejection.

Effect of ZnO addition and concurrent reduction of V2O5 on network formation and elastic properties of lead vanadate (55 − x)V2O5–45PbO–(x)ZnO glass system

Elastic properties of lead vanadate (55−x)V2O5–45PbO–(x)ZnO glasses were investigated using ultrasonic velocity measurements by pulse-echo-overlap technique at room temperature. Results from the study showed that both longitudinal and shear velocities decreased at x=5mol% with the increase of ZnO concentration. The independent longitudinal and shear moduli, CL and μ and Young's modulus (Y) also showed decreasing trend at x=5mol% as the fraction of ZnO increases. FTIR analysis showed an increase in non-bridging oxygen (NBO) as indicated by the increase in intensity of VO4 assigned peaks at x=5mol% while the increase in intensity of VO5 assigned peaks at x>5mol% indicates increasing bridging oxygen (BO). Analysis of the experimental results using the bulk compression and ring deformation models showed that the calculated value of Kbc was higher than that of Ke but Kbc/Ke ratio drops from 2.16 (x=5mol%) to 1.94 (x=10mol%) indicating that bond bending or ring deformation was slightly reduced with addition of ZnO.

Preparation and characterization of lead and zinc tellurite glasses

Glasses of two systems: xPbO–(100 − x)TeO 2 ( x = 13, 15, 17, 19 and 21 mol%) and yZnO–(100 − y)TeO 2 ( y = 18, 20, 22, 25, 30, 33 and 35 mol%) were prepared at two melt-cooling rates and characterized by density, UV–visible and Raman spectroscopy, DSC and XRD measurements. ZnO produces a larger compaction in the tellurite network than PbO. Density decreases with melt-cooling rate in both glass series. DSC studies found that the glass transition temperature decreases with increase in PbO concentration in lead tellurite glasses, but increases with increase in ZnO concentration in zinc tellurite glasses. Lead tellurites prepared at higher cooling rates were mostly amorphous while samples containing 19 and 21 mol% of PbO, prepared at slower cooling rates were translucent glass–ceramics containing crystals of PbTeO 3, Pb 2Te 3O 8 and TeO 2. These slowly cooled samples exhibit an absorption shoulder in the UV–visible absorption spectra, just below the absorption edge. This is attributed to excitonic transitions in nanocrystals that coexist with glassy phase in slowly cooled samples. Raman scattering studies found that the addition of PbO and ZnO produces an increase in the intensity of the absorption band between 720 and 745 cm −1 relative to the intensity of band between 645 and 670 cm −1. This is due to the continuous distortion of symmetry of TeO 4 units, leading to the creation of TeO 3+1 polyhedron and/or TeO 3 trigonal units. Raman studies found a very sharp peak at 76 cm −1 in both lead and zinc tellurite glasses. The position of this peak was independent of the glass composition.

Local structure and photoluminescent characteristics of Eu3+ in ZnO–SiO2 glasses

The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2.

Interface reactions between manganese zinc ferrite single crystals and SiO2-PbO-ZnO ternary systems

Interface reactions between Mn-Zn ferrite single crystals and SiO2-PbO-ZnO ternary systems were investigated using scanning electron microscope, electron probe microanalyzer, and x-ray diffractometer. The addition of ZnO in a SiO2-PbO glass resulted in inhibition of formation of the intermediate phase and suppression of dissolution of the ferrite. The interface morphology became a dendrite structure with increase of ZnO concentration in the glass. Appearance of the anomalous concentration profile of Zn and Mn at the ferrite adjacent to the interface was investigated in terms of the dissolved quantity of Mn and Zn ion. It was found that Zn ion has dissolved from the ferrite into the glass melt during the reaction and Mn ion in the ferrite dissolved into the glass melt more than Zn ion, resulting in changing the undissolved ferrite adjacent to the interface into a Zn-rich Mn-Zn ferrite, Mn0.16Zn0.85Fe2O4, after reaction with 57SiO2-38PbO-5ZnO (in mol %) glass. It was considered that the source of the hump of Zn concentration at the ferrite adjacent to the interface would be the undissolved, remaining Zn ions. A microscopic model was suggested.

Cathodic processes on zinc in alkaline zincate solutions

The charging process of alkaline zinc secondary batteries is accompanied by the formation of hydrogen. Both the current and the coulombic efficiency, and in part the energy efficiency, are dictated by the production of hydrogen. Gasometric methods are used to determine the rates of hydrogen evolution and a potentiodynamic polarization method is employed to study the behaviour of zinc in alkaline solutions. It is found that an increase in ZnO concentration and a decrease in KOH concentration lower the rate of hydrogen evolution.