Doped Zinc Oxide Nanopowders Research Articles

Coprecipitation synthesis of transition metal (Al, Mn, Cu, Ag) doped zinc oxide nanopowders: characterization, photocatalytic test, and comparison study

Coprecipitation synthesis of transition metal (Al, Mn, Cu, Ag) doped zinc oxide nanopowders: characterization, photocatalytic test, and comparison study

Physiochemical characterization of sodium doped zinc oxide nano powder for antimicrobial applications

Zinc oxide (ZnO) is one of the semiconductor materials with unique antimicrobial properties towards various microorganisms. In this article, pure and Na doped ZnO nanopowders were synthesized by easiest and cost-effective co-precipitation process. X-ray diffraction (XRD),Fourier transform infrared spectroscopy(FT-IR), ultraviolet – visible (UV – Vis) spectroscopy, scanning electron microscopy(SEM), and Energy dispersive X-ray analysis (EDAX) techniques were used to characterize the particle size, surface morphology and chemical composition of prepared materials. The XRD analysis revealed that the samples exhibiting hexagonal wurtzite crystal structure with high crystallinity and the average crystallite size values increased from 23.51 to 28.118 nm. The UV – Vis spectroscopy results exposed that the bandgap energy (Eg) of the samples with the values in the range of 3.068–3.301 eV. The SEM micrographs showed that the morphology of the of synthesized particles are hexagonal and spherical in nanometric size. The EDX spectra confirmed the elemental composition of Na, Zn and O in the crystal lattice and FTIR spectroscopic data proved the formation of functional groups and the presence of chemical bonding at the ZnO interface.Antibacterial activity of pure and Na doped Zinc oxide nanoparticles against Gram-negative pathogenssuch as Escherichia coli, Pseudomonas aeruginosa & Klebsiella pneumoniae and Gram-positive pathogens such as Staphylococcus aureus reveal that the zone of inhibition increases with increasing Na concentration. The antifungal activity against Aspergillus and Candida was investigated.These results demonstrated that the pure and Na doped ZnO samples exhibit enhanced antibacterial and antifungal activity with increasing particle sizein presence of visible light and they could be used as good antibacterial as well as antifungal agents.

Iron and Copper Doped Zinc Oxide Nanopowders as a Sensitizer of Industrial Energetic Materials to Visible Laser Radiation.

The development of methods ensuring reliable control over explosive chemical reactions is a critical task for the safe and efficient application of energetic materials. Triggering the explosion by laser radiation is one of the promising methods. In this work, we demonstrate a technique of applying the common industrial high explosive pentaerythritol tetranitrate (PETN) as a photosensitive energetic material by adding zinc oxide nanopowders doped with copper and iron. Nanopowders of ZnO:Fe and ZnO:Cu able to absorb visible light were synthesized. The addition of one mass percent nanopowders in PETN decreased the threshold energy density of its initiation through Nd:YAG laser second harmonic (2.33 eV) by more than five times. The obtained energetic composites can be reliably initiated by a CW blue laser diode with a wavelength of 450 nm and power of 21 W. The low threshold initiation energy and short irradiation exposure of the PETN-ZnO:Cu composite makes it applicable in laser initiation devices. PETN-ZnO:Cu also can be initiated by an infrared laser diode with a wavelength of 808 nm. The proposed photochemical mechanism of the laser-induced triggering of the explosion reaction in the studied energetic composites was formulated. The results demonstrate the high promise of using nanomaterials based on zinc oxide as a sensitizer of industrial energetic materials to visible laser radiation.

Optimization of Gallium concentration to improve the performance of ZnO nanopowders for nanophotonic applications

This study reports the effects of gallium concentration on the properties of doped zinc oxide nanopowders. Both pure and gallium doped zinc oxide (GZO) nanoparticles were prepared via a simple and effective sol-gel method. The structural, morphological and optical properties of synthesized GZO nanopowders were investigated using different characterization methods such as X-ray diffraction, Raman, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, UV–Vis diffuse reflectance spectroscopy, Transmission electron microscopy, Photoluminescence spectroscopy, X-ray and ion-beam-induced luminescence (IBIL) measurements. Firstly, in the presence of Ga ions in the host the purity of synthesized sample was evaluated by X-ray diffraction analysis. X-ray photoelectron spectroscopy confirmed the presence of bonding states of Zn, O, and Ga on the surface of powders. Raman spectroscopy analysis showed that the increase of Ga content upper than 1 at.% leads to an increase in the number of defects in the ZnO lattice. Field emission scanning electron microscopy (FESEM) confirmed that the uniform integration of spherical and hexagonal rod shape particles can be found in the doped samples. According to FESEM images, the particle size of prepared nanopowders increased from 101 to 200 nm by increasing in the Ga doping concentration. The photoluminescence, X-ray and ion beam induced luminescence results of the pure and doped ZnO powders revealed novel blue-green emission band from 400 up to 550 nm at room temperature. Optical and structural studies confirmed the optimized Ga concentration is 1 at.%.

ZnO nanopowders doped with bismuth oxide, from synthesis to electrical application

Bismuth doped ZnO nanopowders with doping concentrations between 0 and 7 %mol were successfully synthesized with a soft chemistry method: the sol-gel route. This method allows obtaining powders with a good quality in a nanometric size range. The well-defined optimal conditions for the synthesized powders are given. The hydrated zinc acetate dissolved in ethylene glycol is used as a precursor for the zinc oxide (ZnO), with different small amount of Bi concentrations (1%, 3%, 5% and 7%). After calcination at 500 °C, the powders are consolidated into pellets and sintered using a conventional furnace and then characterized by: X-ray diffraction, SEM, TEM, and J(E) electrical measurements. Finally, the obtained material has been used to prepare varistors.The XRD patterns indicate that pure and Bi doped ZnO are solid solutions with average grain sizes varying between 65 nm and 48 nm. The β-Bi2O3 liquid phase of tetragonal structures appears as a secondary phase for a 5% mol concentration of Bi. High-resolution TEM images of Bi doped ZnO particles indicate that during the sintering of Bi-doped ZnO, the growth of particles leads to a change in the microstructure of ZnO giving semi-transparent cylindrical nanotubes.J(E) results indicate that the content of Bi increases the nonlinearity coefficient α and the breakdown fields VB of the binary Zn %Bi-O varistors. The 7% doped Bi-ZnO varistor gives the best electrical characteristics for varistors.

Thermochromic and infrared emissivity characteristics of cobalt doped zinc oxide for smart stealth in visible-infrared region

Cobalt doped zinc oxide nanopowders were prepared via solid-state reaction. The influences of calcining temperatures on crystal structure, morphology, emissivity and color change of the Zn1-xCoxO nanopowders were studies detailedly. The results indicate that the substitute for Zn2+ by Co2+ in hexagonal wurtzite ZnO usefully sintering temperatures are 900–1200 °C. Moreover, the crystallinity, the oxygen vacancy content and the amount of Co2+ substituted Zn2+ in the Zn1-xCoxO nanopowders are increasing with the heating temperature improving. All the samples show reversible thermochromism, which can reversible color change from green to yellow by rising test temperature from 25 to 800 °C. Meanwhile, the largest emissivity change is 0.321 as the test temperature changes between 25 and 800 °C in the sample heated at 1100 °C. The Zn1-xCoxO has great potential applications for smart adaptive camouflage in visible-infrared region.

Hydrothermal derived nanostructure rare earth (Er, Yb)-doped ZnO: structural, optical and electrical properties

The structural, optical and electrical properties of undoped and rare-earth (Er, Yb) doped zinc oxide (ZnO) nanopowder samples synthesized by hydrothermal method were investigated. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy. The optical properties of undoped and rare-earth (Er, Yb) doped ZnO were carried out with UV–visible diffuse reflectance spectroscopy techniques. XRD results reveal that Yb and Er doped ZnO nanopowders have single phase hexagonal (Wurtzite) structure without any impurities. SEM analysis indicate that dopants with different radii affected the surface morphology of ZnO nanostructures. The optical band gap of all samples were calculated from UV–Vis diffuse reflectance spectroscopy data. We have obtained band gap values of undoped, Er and Yb doped ZnO as 3.24, 3.23, 3.22 eV, respectively. Electrical characterization of the samples were made in the 280–350 K temperature range using Van der Pauw method based on Hall effect measurement. The carrier concentrations decreased for both Er and Yb doping while the Hall mobility and electrical resistivity increased with Yb, Er doping compared to undoped ZnO nanopowder at room temperature. The temperature dependent resistivity measurements of Er doped ZnO showed a metal–semiconductor transition at about 295 K, while Yb doped ZnO showed characteristic semiconductor behavior.

Enhanced gas sensing performance of indium doped zinc oxide nanopowders

Indium doped zinc oxide sensors were synthesised, characterised and tested towards a range of gases, displaying particular sensitivity to ethanol.

The effect of the starting powders particle size on the electrical properties of sintered Co doped ZnO varistors

Pure and Co doped zinc oxide nanopowders have been synthesized by sol–gel route. The obtained powders, after calcination in air at 550, 650, 750 and 850 °C, were consolidated and sintered using microwaves. The effect of sintering temperature on the density and electrical properties was investigated. The best characteristics are obtained using a sintering temperature equal to 1,075 °C. The powders and sintered samples are characterized by X-ray diffraction, microstructure images, density and electrical measurements. The studied nanopowders have: a density of 5.22 (g/cm3), a breakdown voltage of 446.5 V/mm and a coefficient of non-linearity of 11.48 for ZnO doped with 7 mol% Co, and a density of 5.19 (g/cm3), a breakdown voltage of 292.5 V/mm and a non-linearity coefficient of 11.62 for ZnO doped with 5 mol% Co. The XRD results indicate that pure and Co doped ZnO powders are solid solutions crystallizing in pure wurtzite structure, and consisted of a mixture of nanoparticles with an average grain size between 36 and 210 nm. The grain size decreases with increasing Co concentration and reaches its lowest value at 7 mol% Co and increases with increasing temperature. On the other hand the increase of Co concentration leads to a decrease of the porosity and an increase of the density of samples sintered at 1,070 °C and leads also to an increase of the electric field (E) in the non-linear area. The samples of 5 mol% Co sintered at 1,075 °C, show that the non-linear coefficient α decreases by increasing of calcined temperature, therefore increases with decreasing of grain and particle sizes.

Systematic approach on the fabrication of Co doped ZnO semiconducting nanoparticles by mixture of fuel approach for Antibacterial applications

Zinc oxide (ZnO) is a wide band gap semiconductor (3.2eV) with a high exciton binding energy (60meV), where it has wide applications in advanced spintronic devices. The theoretical prediction of room temperature ferromagnetism and also antibacterial activity will be possible through the investigation of diluted magnetic semiconductors (DMS), such as transition metal doped ZnO, especially Cobalt doped ZnO. The aim of the work is the synthesis of Cobalt (Co) doped ZnO nanopowders were prepared Zn1−xCoxO (0⩽x⩾0.09) nanopowders from Sol–Gel auto combustion method have been synthesized with precursors such as Zinc and Cobalt nitrates with the assistance Ammonium acetate & Urea as fuel by increasing the cobalt concentration in zinc oxide and their structural, morphological, optical, Thermal, magnetic and antibacterial properties were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission Electron microscope (TEM), UV–visible spectroscopy, thermo gravimetric/differential thermal analysis (TG/DTA) and vibrating sample magneto meter (VSM). From the antibacterial studies, against gram positive Bacillus subtilis bacteria is most abundant bacteria in soil and indoor atmosphere, which affects the stored spintronic devices so that the devices should be made with antibacterial activity of DMS like Co doped ZnO. In this article is found that ZnO:Co nanopowders with higher Co doping level (0.07 and 0.09wt%) exhibit good antibacterial efficiency. The magnetization curves obtained using vibrating sample magnetometer (VSM) show a sign of strong room temperature ferromagnetic behavior when the Co doping level is 0.05wt% and a weak room temperature ferromagnetic behavior Co doping level is below 0.07wt%, and also they found to exhibit antiferromagnetic and paramagnetic properties, when the Co doping levels are 0.07 and 0.09wt%, respectively, to enhance and increase the special magnetic and antibacterial property for sophisticated devices for the sustainable technologies.

Indium doped zinc oxide nanopowders for transparent conducting coatings on glass substrates

Crystalline indium doped zinc oxide (IZO) nanopowders were synthesized using hydrothermal treatment processing. Increasing the doping ratio of indium in the zinc oxide significantly influences the phase structure and shape of the nanopowders resulting in nanorod to nanoparticulate morphologies. As the doping profile increases, the crystallite size decreases, the band gap energy blue shifts and the specific surface area increases (measured by BET method). Additionally Raman spectroscopy exhibited shifts of several peaks, as well as revealed new peaks, confirming the substitution of indium ions within the zinc oxide lattice sites. An IZO suspension made of IZO nanoparticles (In/Zn = 3 atm.%) with a zeta potential greater than 30 mV at pH = 6 was successfully spin-coated on glass substrates for to make transparent conductive coatings evincing sheet resistances as low as 35 kΩ□ (ρ = 4.9 × 10−3 Ω m,) with transmission in the visible range as high as 90 %.

Preparation and Characterisation of Al doped ZnO Nanopowders

Abstract Zinc oxide (ZnO) and aluminium (Al) doped zinc oxide nanopowders were prepared using sol-gel method. The structural properties were studied using X-ray diffraction technique (XRD). It is observed that doping of aluminium significantly reduces the crystallite size and also affects the intensity ratio of crystal planes. The powders with wurtzite structured hexagonal phase are also characterized using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). From the optical transmittance studies, it is observed that there is increase in the band gap for Al doped ZnO samples. The Photoluminescence (PL) spectrum reveals the presence of broad green emission peak at 509 nm for the doped sample.

Nanostructure and Magnetic Properties of Nickel Doped Zinc Oxide Nano-Powders Prepared by Coprecipitation Method

Nanostructure and Magnetic Properties of Nickel Doped Zinc Oxide Nano-Powders Prepared by Coprecipitation Method

Structural and luminescence properties of pure and Al-doped ZnO nanopowders

Abstract Pure and Al doped zinc oxide nanopowders have been synthesized by sol–gel route. This is a simple and inexpensive method permitting to obtain a very small grain size powders. Zinc acetate dehydrate was first dissolved in a mixture of 2-methoxyethanol and mono-ethanolamine (MEA) solution, were used as a solvent and stabilizer respectively and doped with a quantity of aluminum nitrate, varying from 0 to 10 mol%. The obtained gel is then calcinated in air at 500 °C. The samples are characterized by XRD, SEM and photoluminescence (PL) studies. The XRD results indicate that pure and Al-doped ZnO powders are solid solutions crystallizing in pure wurtzite structure, and consisted of a mixture of nanoparticles with grain size between 23 and 36 nm. The grain size decreases strongly with increasing Al concentration and reaches its lowest value at 5 mol% Al. The PL spectra show that the most important establishment is that the powders show luminescence peaks from green to ultraviolet light, and thus can be used to manufacture transmitters using these emissions. The peaks connected to the blue luminescence are the most intense, and they are generated by transitions involving (Zn i ). The SEM images show a formation of pebbles with sizes decreasing with Al concentration and a morphology evaluating, qualitatively, from pebbles without cavities to highly porous ones.