Zinc Oxide Microrods Research Articles

Growth and Photoluminescence Properties of ZnO Microrods

Zinc oxide (ZnO) microrods were grown by the floating zone method, the as-grown ZnO microrods have uniform size. Scanning electron microscope image reveals that the ZnO microrods are grown with a hexagonal structure, well faceted ends and side surfaces. Most of ZnO microrods have diameters of about 20-30 mm and lengths of about 1-2 mm. Polarizing microscopy image of ZnO microrods shows that they have high crystal quality. The X-Ray diffraction pattern shows that microrods have vertical orientation and the crystal structure of ZnO is wurtzite type. At low exciting intensity, ultra violet range emission was found and the growth process of ZnO microrods was discussed.

The different types of ZnO materials on the performance of dye-sensitized solar cells

Different types of zinc oxide (ZnO) materials such as micro-rods, textured, nanoparticles and nanorods have been synthesized as photoanodes via a simple method for dye-sensitized solar cells (DSSCs). The relationship between the optical transparency and the device efficiency has been correlated with respect to film thickness. The maximum conversion efficiency is recorded from the device containing slantingly grown ZnO nanorods. Besides, the lower conversion efficiency is obtained from the device with ZnO micro-rods. A plausible schematic diagram is drawn to explain the reason for the higher power conversion in slantingly grown ZnO nanorods over the well-aligned nanorods.

Liquid phase synthesis of ZnO microrods highly oriented on the hexagonal ZnO sheets

We have successfully synthesized zinc oxide microrods perpendicularly oriented on hexagonal ZnO sheets by a simple heat treatment approach using LDH (layered double hydroxide) precursor in an aqueous solution. The synthesized ZnO microrods have an average diameter of 500 nm and length of 2–3 μm, and form highly-oriented array. In this work, the effect of heating temperature and time on morphology and orientation of ZnO microrods was studied experimentally and the formation mechanism was discussed in detail. Transformation from hexagonal precursor to ZnO microrods can be attributed to dissolution and re-precipitation of the precursor, which should be caused by its thermal unstability under heating temperature.

Microwave synthesis of zinc sulfite and porous zinc oxide microrods

ZnSO(3) microrods with uniform size and shape can be prepared under microwave irradiation at much higher speed than a conventional heating bath, usually in minutes. The annealing of ZnSO(3) microrods produced porous ZnO microrods with pore size between 50-200 nm.

Synthesis of zinc oxide microrods and nano-fibers with dominant exciton emission at room temperature

Employing a simple chemical synthesis method, hexagonal-shaped zinc oxide microrods and zinc oxide nano-fibers were deposited on pyrex-glass and aluminum substrates, respectively. Both kinds of deposits showed zincite crystalline phase with lattice parameters: a=3.2498Å and c=5.2066Å. Microrods showed very uniform wide and large sizes of around 1 and 10μm, respectively. Both deposits were homogeneous over all substrate surfaces. Microrods and nano-fibers resulted with good optical quality and with preferential crystalline growth in [1010] and [0001] directions. The principal optical characteristics for both microrods and nano-fibers were: a) room-temperature photo and cathodo-luminescent spectra with strong exciton emission centered around 390nm and with FWHMs around 125 and 160meV, respectively, b) poor photo and cathode-luminescent emissions in the visible region of the electromagnetic spectrum, c) energy band gap of 3.32eV, d) good emission efficiency supported by the not-required high energy densities to obtain strong exciton emission and e) good ZnO stoichiometry endorsed by photoluminescent results. These characteristics make of these microrods and nano-fibers good for potential photonic applications.

Sintering, microstructure, mechanical, and antimicrobial properties of HAp‐ZnO biocomposites

The implant associated infection is widely considered as a major concern in the field of biomedical applications and this has been the driving force for developing HAp-based biomaterials with antibacterial additives for possible use in prosthetic devices. In our present work, we sintered Hydroxyapatite (HAp) with different concentrations of zinc oxide microrods (ZnO) at 1250°C to produce HAp-ZnO biocomposites. In vitro antimicrobial studies were carried out to understand how ZnO addition (up to 30 wt %) to HAp leads to the improvement in bacteria static/bactericidal property and thereby, can reduce bacterial infection on implant surface. Both Gram positive (S. aureus, S. epidermidis) and Gram negative bacteria (E. coli) were used for this study. After 4 h of incubation, it was observed that microbial activity on HAp-20 wt % and HAp-30 wt % ZnO are significantly reduced in comparison to control sample, independent of type of bacterial cells. Despite such improvement in antimicrobial property, an increase in ZnO addition was found to have modest influence on fracture toughness or hardness properties. A maximum up to 1.7 MPam(1/2) indentation fracture toughness and hardness of up to 6.8 GPa were measured in HAp-ZnO biocomposites.

Zinc oxide microrods prepared by sol‐gel immerse technique

PurposeZinc oxide (ZnO) is an emerging optoelectronic material due to its various functional behaviors. The purpose of this paper is to report on the fabrication and characterizations of ZnO microrods.Design/methodology/approachZnO microrods were synthesized using sol‐gel immerse technique on oxidized silicon (Si) substrates. The oxidized Si substrates were immersed in ZnO aqueous solution for different times ranging from three to five hours. The surface morphologies of the ZnO microrods were examined using scanning electron microscope (SEM). In order to investigate the structural properties, the ZnO microrods were measured using an X‐ray diffractometer (XRD). The optical properties were measured using a photoluminescence (PL) spectrophotometer.FindingsCharacterization from SEM shows an enhanced growth of the ZnO rods with increasing immerse time. XRD characterizations demonstrate sharp and narrow diffraction peaks peculiar to ZnO, which implies that the rod is of high crystallinity. Based on the PL spectra, long immerse time results in the high peak in the UV region.Originality/valueThis paper concludes that the immerse time exerts an influence on the ZnO microrods. A longer immerse duration is preferred in the fabrication of the ZnO microrod, which is considered an emerging material for many advanced electronic and optoelectronic applications.

Local electromechanical properties of ZnO thin films and micro crystals

AbstractHigh-resolution piezoresponse force microscopy (PFM) was used to measure the out-of-plane (effective longtitudinal) and in-plane (effective shear) piezoresponse of zinc oxide films and microrods. Thin films were deposited by pulsed laser deposition (PLD) and micro rods formed from solution. Measurements of three components of piezoresponse, one out-of-plane (OPP) and two in-plane (IPP) signals, allowed the construction of 3D piezoelectric maps reflecting the polycrystalline nature of the films. Both the IPP and OPP piezoresponse signal distributions are analyzed based on the particular texture of the films. It was observed that the central part of microrods contains polarization inversion with head-to-head ferroelectric-like domains. The as-grown domain boundaries were always parallel to the (0001) basal plane. Analysis of the PFM piezoresponse images was done based on the hexagonal structure of ZnO and topographic features along the hexagonal axis.

CBD법에 위한 ZnO 마이크로 막대 구조체의 2차원 배열 및 수직정렬

A periodic away of zinc oxide(ZnO) micro-rods as fabricated by using chemical bath deposition and photo-lithography. Vertically aligned ZnO micro-rods array was successfully grown by chemical bath deposition method on ZnO seed layer. The ZnO seed layer was deposited on glass and the patterning was made by standard photo-lithography technique. The selective growth of ZnO micro-rods as achieved with the masked ZnO seed layer. The fabricated ZnO micro rods were found to be single crystalline and have grown along hexagonal c-axis direction of (0002) which is same as the preferred growth orientation of ZnO seed layer.

Particulate assisted growth of ZnO nanorods and microrods by pulsed laser deposition

Zinc oxide (ZnO) thin films were deposited on the gallium nitride (GaN) and sapphire (Al 2O 3) substrates by pulsed laser deposition (PLD) without using any metal catalyst. The experiment was carried out at three different laser wavelengths of Nd:YAG laser ( λ = 1064 nm, λ = 532 nm) and KrF excimer laser ( λ = 248 nm). The ZnO films grown at λ = 532 nm revealed the presence of ZnO nanorods and microrods. The diameter of the rods varies from 250 nm to 2 μm and the length varies between 9 and 22 μm. The scanning electron microscopy (SEM) images of the rods revealed the absence of frozen balls at the tip of the ZnO rods. The growth of ZnO rods has been explained by vapor–solid (V–S) mechanism. The origin of growth of ZnO rods has been attributed to the ejection of micrometric and sub-micrometric sized particulates from the ZnO target. The ZnO films grown at λ = 1064 nm and λ = 248 nm do not show the rod like morphology. X-ray photoelectron spectroscopy (XPS) has not shown the presence of any impurity except zinc and oxygen.

Controlled Fabrication of Highly Oriented ZnO Microrod/Microtube Arrays on a Zinc Substrate and Their Photoluminescence Properties

Well-aligned zinc oxide microrod and microtube arrays with high aspect ratios were fabricated on zinc foil by a simple solution-phase approach in an aqueous solution of ethylenediamine (en). The shape of the ZnO microstructures can be easily modulated from rods to tubes by adding cetyl trimethyl ammonium bromide (CTAB) into the reaction system. Control experiments demonstrate that some reaction parameters, such as the concentration of ethylenediamine, the kind of surfactant, reaction time, and the temperature, all have direct influences on the morphology of the products. Based on the early structure arising from arrested growth (nanosheets), a reasonable mechanism for the growth of ZnO microrods and microtubes has been proposed. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence emission.

Temperature dependence of ZnO rods produced by ultrasonic spray pyrolysis method

Zinc oxide (ZnO) microrods were prepared at different substrate temperatures by ultrasonic spray pyrolysis technique on glass substrates. The X-ray diffraction patterns show that obtained rods are composed of wurtzite-type and mainly grow along the [0 0 2] direction. Scanning electron microscope images show that the diameters of ZnO rods and the distances among the rods increase with increasing substrate temperature. In addition, the optical measurements reveal that transmittance and the band gap energies of films increase with increasing substrate temperature.

Structural characterization of ZnO nano-chains studied by electron microscopy

We have examined the morphology of zinc oxide (ZnO) fibers exhibiting high-performance of photocatalyst in visible-light region, by means of scanning and transmission electron microscopy. The ZnO fibers consist of ZnO micro-rods, and each of the micro-rods further is constructed from ZnO nano-crystals, which have high crystallinity, clean surfaces and diameters of a few tens of nanometers. From nano-beam diffraction, the ZnO nano-crystals are connected without definite orientation relations. The microstructure of surfaces is suspected to be strongly related to the visible-light photocatalytic ability of this fiber.

Synthesis and characterization of spray pyrolysis Zinc Oxide microrods

Zinc Oxide (ZnO) microrods were prepared by ultrasonic spray pyrolysis technique on glass substrates. The X-ray diffraction (XRD) patterns and scanning electron microscope images show that obtained rods are composed of wurtzite-type ZnO with diameters of about 1–3 μm and lengths ranging from 1 to 3 μm. The XRD patterns also show that hexagonal ZnO rods mainly grow along the [002] direction. The optical measurements reveal that films have a maximum transmittance of about 80% and a direct band gap of 3.6 eV.

Synthesis of zinc oxide fibers from precursor bis(acetylacetonato)zinc: Tracking the mineralization process and micro- and nano-structural changes

Zinc oxide (ZnO) fiber was prepared from the precursor bis(acetylacetonato)zinc (Zn(acac) 2). Fine polycrystalline Zn(acac) 2 fiber was obtained by the sublimation of Zn(acac) 2 powder. When the Zn(acac) 2 fiber was decomposed with superheated steam, it was converted to ZnO fiber, while maintaining the original shape of the Zn(acac) 2 fiber. At this stage, polycrystalline ZnO, aggregated ZnO single crystal grains, which had diameters of a few nanometers, were present along with relatively large amounts of carbon (C) and hydrogen (H). The ZnO fiber sample produced after crystal grain growth by heat treatment contained almost no C and H, and nearly complete mineralization had been achieved. This ZnO fiber consisted of ZnO microrods, and these microrods consisted of ZnO nanorods. The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains, which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers. The visible-light photocatalytic ability of the ZnO fiber may be strongly related to the nanosized-single-crystal grains located on the surface that have diameters of a few tens of nanometers.

Aqueous purpose-built nanostructured metal oxide thin films

A novel concept in materials chemistry as well as an aqueous low-temperature thin film growth technique has been developed to create a new generation of smart and functional metal oxide thin film materials. These materials are modelled, designed and engineered to match the physical and structural requirements of their applications. This concept is well-sustained by a thermodynamic model monitoring the nucleation, growth and ageing processes through the chemical and electrostatic control of the interfacial free energy. It allows to monitor the size of nano and microparticles, their surface morphology and their orientation onto substrates as well as the ability to thermodynamically stabilize metastable crystal phases. This template- and surfactant-free aqueous chemical growth method allows generation of, at large scale and low-cost, advanced metal oxides nano- and micro-particulate multilayered thin films with complex architectures. It includes 3-dimensional highly oriented crystalline arrays of ferric oxides nanorods, zinc oxide nanorods, microrods, microtubes, and nanowires. Other applications include nanocomposite thin films consisting of chromium and iron sesquioxide and nanoporous ruthenium/ruthenium oxide thin film grown at low temperature from aqueous solution onto various substrates.