Zinc Films Research Articles

Determination and analysis of optical constants and dispersion energy parameters of Zn(S,O) thin films

Zn(S,O) thin films was elaborated by annealing in air and sulfur atmospheres the zinc films deposited by thermal evaporation method. The samples were analyzed for their optical properties by using Ultraviolet–Visible-near Infrared spectroscopy. The optical constants and the dispersion parameters of the films were calculated from the analysis of the transmittance and reflectance data in the spectral range 300–1800 nm. The band gap energy varied from 3.27 to 3.08 eV depending on the sulfur content. The bowing parameter was calculated as 2.45 eV. Swanepoel model was employed to study the wavelength dependence of the refractive index. The lattice dielectric constant εL, the plasma frequency ωp and the ratio of the carrier density to the carrier effective mass N/m* were calculated from the examination of the refractive index. Wemple-Di Domenico single oscillator model was applied to determine the dispersion parameters of the samples such as the high-frequency dielectric constant ε∞, the oscillator energy E0 and the dispersion energy Ed.

Optical spectroscopy characterization of zinc tetra pyridel porphine (ZnTPyP) organic thin films

Thermal evaporation technique was used to grow thin films of tetra pyridel-porphine zinc (ZnTPyP) onto quartz substrate. Optical constants, namely refractive index n and absorption index k, of the as-deposited ZnTPyP thin films have been estimated via spectrophotometric measurements of the transmittance and the reflectance within the spectral range (200–2500) nm. Depending on the single oscillator and Drude models, some associated parameters including the oscillation energy Eo, the dispersion energy Ed the optical dielectric constant ε∞, the lattice dielectric constant εL and the ratio of the free carriers concentration to their effective mass N/m∗ were determined. Urbach curves include 2 various exponential regions with different slopes. The absorption analysis was performed with the purpose of concluding the scattering mechanism and the type of the electronic inter-band transition for the studied thin film. Also, different dispersion and absorption parameters were determined. In addition, at lower photon energy, the third order nonlinear susceptibility χ(3) and the nonlinear refractive index n2 were reported and interpreted.

Corrosion behavior of the chitosan‑zinc composite films in sulfate-reducing bacteria

Sulfate-reducing bacteria (SRB) are one of the chief inducers of microbiologically influenced corrosion in marine environment. In our previous work, a novel chitosan‑zinc film was electrodeposited and found to be effectively antibacterial, so research on the corrosion behavior of chitosan‑zinc films in SRB medium is highly significant for estimating the films to be applied in real-sea environment. In this paper, detection of SRB metabolism, electrochemical methods and surface analyses were performed to clarify the corrosion behavior. During 6 d exposure in SRB, obvious inhibition on SRB growth and metabolism were found by monitoring the environment corrosive factors. By calculating the corrosion rate and analyzing surface morphologies, chitosan‑zinc films showed relatively high corrosion resistance. After exposure, biofilm together with corrosion products formed on zinc film, while corrosion product layer with little bacteria attached on chitosan‑zinc composite film. Further electrochemical results showed that the addition of chitosan did not change the anodic and cathodic behavior of the films, but enhanced the corrosion resistance by reducing the corrosive ability SRB medium, inhibiting bacteria attachment and raising the films' electric conductibility to a certain extent.

Pore Shape Changes and Apatite Formation on Zn and Si Ion-Doped HA Films of Ti-6Al-4V After Plasma Electrolytic Oxidation Treatment.

In this study, pore shape changes and apatite formation on zinc (Zn) and silicon (Si) ion-doped hydroxyapatite (HA) films of Ti-6Al-4V by plasma electrolytic oxidation (PEO) treatment has been investigated by several techniques. The PEO films and the Ti-6Al-4V surface after immersion in SBF were observed by X-ray spectroscopy, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. The number of pores decreased as Zn ion concentration increased from 5Zn to 10Zn. The maximum size of pores were increased from 5Zn to 20Zn concentration, whereas, the minimum size of pores decreased. The amount of bone-like apatite formation for the 5Zn/5Si sample was higher than those of other samples immersed in SBF.

The effect of zinc thickness on corrosion film breakdown of Colombian galvanized steel

This work studies the corrosion behaviour of Colombian galvanized steel in solutions of chloride and sulphate ions. The effect of the thickness and exposure time on the film’s breakdown susceptibility and protectiveness of the corrosion products were studied using potentiodynamic polarization curves and electrochemical impedance spectroscopy. The corrosion products were analysed using SEM-EDS and XRD. The samples with a higher thickness level in the zinc film (Z180) have the lowest corrosion rate. In this case, one of the products that was formed by the chemical reactions that occurred was Zinc hydroxide, which exhibits a passive behaviour as observed in the Pourbaix curves of the obtained potentials and in how the different Ph levels of the solutions worked. The sheets with the highest thickness (Z180) had the best performance, since at the end of the study they showed the least amount of damage on the surface of the zinc layer. This is because the thickness of the zinc layer favours the formation of simonkolleite, which is the corrosion product that protects the material under the conditions of the study.

Synthesis of ZnO Thin Films Doped with Ga and In: Determination of Their Composition through X-Ray Spectroscopy and Inductively Coupled Plasma Mass Spectrometry

An approach is proposed to study the composition of synthesized thin zinc films doped with In and Ga through local X-ray spectral analysis (LXSA) and inductively coupled plasma mass spectrometry (ICP-MS). A relationship between the amount/distribution of additives in the sample and synthesis conditions on rotating substrates is found. The results of determining the dominant impurities in film solutions with ICP-MS are used to validate those obtained with the LXSA method without sample preparation. To find doping impurities at an amount less than 1 at % is possible only through the ICP-MS method.

Removing the oxide layer on the A380 substrate of AM60/A380 bimetallic castings by the zincate process followed with galvanizing

The bimetallic experiments in combination with “zincate + galvanizing” surface treatment of the A380 substrates were carried out. The effect of surface treatment on the interfacial microstructure and shear strength of AM60/A380 bimetallic castings was investigated. The results showed that the wetting between molten AM60 and A380 substrates with the “zincate + galvanizing” surface treatment was excellent. The “zincate + galvanizing” surface treatment removed the natural oxides on the A380 surfaces which were replaced by the zinc film. The “zincate + galvanizing” surface treatment could also improve the shear strength of AM60/A380 bimetallic castings. The bimetallic casting with the preheating time of 110s and substrate preheating temperature of 560 °C had the optimal shear strength of 63.8 MPa.

INFLUENCE OF ELECTRIC FIELD ON ADHESION AND STRUCTURE OF CONDUCTING FILMS ON DIELECTRIC SUBSTANCES

Some results are provided confirming that modifying of the zinc films fabricated on glass substrates by a resulting effect of heat treatment in an atmosphere of dry air and action of cross electric field is possible. Using scanning electron microscopy (measured with the Zeiss Merlin microscope) the surface morphology of the films was studied. Also, the elemental composition of the films by micro-X-ray spectral analysis was studied. On the glass substrates, by the method of vacuum thermal evaporation, zinc films (Zn) with thickness of ~ 500 nm were obtained. In order to form ZnO films, the original films were treated at 250 °C in a dry air atmosphere, and in another case - in addition to the sample a transverse electric field with a potential of 300 V was applied. Platinum films on the silicon dioxide layer were obtained using the method of the ion-plasma sputtering. These layers were investigated by X-ray phase analysis, electron and atomic force microscopy. The thickness of platinum layers was 50 and 100 nm. During the deposition (deposition temperature – 300 °C, deposition rate - 5 nm / min), applied voltage between the platinum film and the silicon plate was 5 V. The films, obtained by applying a biasing, showed a more homogeneous fine-grained structure and a higher rate of growth than the original samples. In this way ZnO films can be manufactured with the extended surface. The possibility of significant changes caused by electric field use in adhesion, structure and conductive properties of the coatings is discussed. The method of depositing platinum on a dielectric substrate with an additional electrostatic field is also substantiated. It is shown that the application of an electric voltage to the film leads to a significant change in the structure of the resulting coating.Forcitation:Pshchelko N.S., Vodkailo E.G., Tomaev V.V., Klimenkov B.D., Koshevoi V.L., Belorus A.O. Influence of electric field on adhesion and structure of conducting films on dielectric substances. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 8. P. 100-104.

Zinc Electrodeposition from deep eutectic solvent containing organic additives

The effect of the addition of a group of organic additives on the electrodeposition behavior of zinc was investigated in choline chloride:ethylene glycol (ChCl:EG) eutectic mixture in the molar ratio of 1:2. Cyclic voltammograms recorded on steel electrode showed a cathodic peak is only observed after reversing of the scan. Chronoamperometric measurements indicated that the deposition of zinc occurs through 3D progressive nucleation mechanism. The morphology of the zinc deposits and was evident that additives influence the deposits morphologies. X-ray diffraction confirmed the presence of crystalline zinc and reveal the grain refinement effect obtained by using the additives selected where the smallest grain size of 31.7nm was obtained in the presence of Dimethyl sulfoxide (DMSO). Moreover the XRD data showed that the addition of additives modified the preferential growth plane. The corrosion resistance properties of the electrodeposited Zn coatings were evaluated in 3% NaCl aqueous solution using potentiodynamic polarization. The results showed that the zinc film deposited with DMSO was the best corrosion resistant coating.

Growth of Zinc Oxide Nanorod and Nanoflower Structures by Facile Treatment of Zinc Thin Films in Boiling De-Ionized Water

In this work, zinc oxide nanostructured films were developed by a facile treatment of the sputter deposited zinc thin films in boiling de-ionized water. Arrays of zinc oxide nanostructures with rod and flower-like shapes were obtained by changing the boiling water treatment time and manipulating the thickness of zinc film. Results of the scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, ultraviolet-visible-near infrared spectroscopy, and photoluminescence techniques indicate that the obtained nanostructures are crystallized stoichiometric zinc oxide. Zinc oxide nanorods and nanoflowers start to form on the surface and progress across the zinc film’s thickness as a function of treatment time in boiling de-ionized water, which allow a controllable method of fabricating semiconducting/metal multilayer coatings. The obtained nanostructured films showed different optical properties depending on starting zinc film’s thickness and boiling water treatment time. In addition, photoluminescence analysis showed that the nanostructured films possess a major energy band gap of 3.28 eV along with two other secondary defects-related energy band gaps of 2.27 and 1.67 eV.

Hydrogen sensors based on gold nanoclusters assembled onto ZnO nanostructures at low operating temperature

In this work, the hydrogen (H2) sensor performance of gold nanoclusters (Au NCs) assembled onto zinc oxide (ZnO) nanostructures films were investigated and compared to ZnO nanostructures films. ZnO nanostructures were prepared by thermal oxidation of zinc films on glass substrate at different oxidation temperatures. Au NCs were assembled onto obtained ZnO nanostructures via photoreduction of HAuCl4 solution. The morphology of ZnO nanostructures were comprised of short rods branched into their ZnO bases. The diameters of cylindrical ZnO nanostructures increased approximately 50 to 90 nm upon increasing the oxidation temperatures. The morphology of Au NCs assembled onto ZnO nanostructures exhibited growth to encapsulate individual ZnO nanostructures as cluster−like with dimensions less than 100–150 nm. The amount of Au NCs assembly was proportion to crystallinity and materials’ stoichiometry of ZnO nanostructures. H2 sensor performance of the films were investigated at different operating temperature in the range of 150–450 °C. It was found that optimum operating temperatures of Au NCs assembled ZnO nanostructures films were 200 °C in all cases less than that 350 °C of pure ZnO nanostructures. Au NCs assembled ZnO nanostructures films had still high H2 sensor response at operating temperature of 150 °C. Furthermore, the sensor response of Au NCs assembled ZnO nanostructures seems to have higher than those ZnO nanostructures and their sensor response was directly proportion to amount of Au NCs. Accordingly, the enhancement of sensor response can be explained in terms of the reaction rate constant (kOxy) by considering the catalytic effect of Au. These results can be further explored for H2 safety sensor in fuel cell due to the demand of high H2 response at the low operating temperature.

Structural and morphological changes with substrate heating in zinc films synthesized by thermal vapor deposition technique

Zinc oxide (ZnO) films are used in numerous applications such as solar cells, gas sensors, nanogenerators, etc., owing to their large band gap, piezoelectric activity and versatile nanostructures. Deposition of zinc films and their subsequent oxidation is considered as one of the successful methods to obtain nanostructured ZnO films. It has been reported that the structural features of the oxide film depends on the characteristics of parent zinc film; which in turn depends on the deposition parameters. In the present work, zinc films were synthesized by thermal vacuum deposition route. In order to understand the effect of substrate heating during deposition, zinc films were deposited on glass with different substrate temperatures, in the range of room temperature to 180 °C. The structural and morphological properties of as-synthesized films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques. The XRD data confirmed that the as-synthesized films have strong (002) preferential orientation. Notable changes were observed such as change in crystallite size, texture coefficient and strain in the films, upon changing the substrate temperature. The morphology of as-synthesized zinc films found to consist of hexagonal-plate like structures. It was observed that the dimensions of the hexagonal-plates were changed in accordance with the substrate temperature. DSC results indicated a depression in the melting point of zinc films compared to bulk zinc and it is attributed to the nanoscale features constituting the film.

Fast synthesis of ultrathin ZnO nanowires by oxidation of Cu/Zn stacks in low-pressure afterglow

The synthesis of ultrathin, single-crystalline zinc oxide nanowires was achieved by treating in a flowing microwave plasma oxidation process, zinc films coated beforehand by a sputtered thin buffer layer of copper. The aspect ratio of the nanowires can be controlled by the following experimental parameters: treatment duration, furnace temperature, oxygen concentration. An average diameter of 6 nm correlated with a mean length of 750 nm can be reached with a fairly high surface number density for very short treatments, typically less than 1 min. The oxidized samples are characterized by means of SEM, XRD, SIMS, HRTEM and EDX techniques. Structural characterization reveals that these nanowires are single-crystalline, with the wurtzite phase of ZnO. Nanowires are only composed of ZnO without copper particles inside or at the end of the nanowires. Temperature-dependent photoluminescence measurements confirm that ZnO nanowires are of high crystalline quality and thin enough to produce quantum confinement.

Comparative analysis of the thickness and electrical conductivity of thin chalcogenide semiconductor films

The structure and thickness of zinc and cadmium chalcogenide semiconductor films are studied by X-ray radiography. The film thickness is shown to be comparable with the half-value layer depth. The electrical conductivity of the films increases upon heating in the hydrogen atmosphere and decreases upon heating in carbon oxide. The opposite trend is observed in the ratio between the electrical conductivity and band gap of the initial and oxidized film surfaces.

‘Rough guide’ evanescent wave optrode for colorimetric metalloporphyrine sensors

When films of zinc 5-(4-carboxyphenyl),10,15,20-triphenyl porphyrin (ZnTPP) are exposed to waterborne amine in pH- neutral or alkaline media, both Q- band and Soret band respond with a change of absorbance due to the donation of amine ‘lone pair’ electrons to the metalloprophyrin π orbital. However, this is difficult to reveal with a conventional spectrometer even under high amine concentration. We therefore introduce optical fibres coated with ZnTPP into a bespoke ‘light balance’ evanescent wave absorbance meter [doi:10.1016/j.snb.2016.05.065]. The light balance makes absorbance changes clearly visible under only 5μM aqueous amine, making PVC membranes redundant. We find sensitivity is higher, and limit- of- detection lower, in the Soret band rather than the Q- band, reflecting the stronger Soret band absorbance. Also, we find that sensitivity is higher, and limit- of- detection approximately two times lower, when rough rather than smooth fibres are used. We believe the rough fibre surface leads to enhanced evanescence, and therefore better overlap of the wave propagating in the fibre with the ZnTPP fibre cladding. We find a limit of detection to waterborne amines below 1μM, which compares well to other sensors for waterborne amines [Korent, S.M. et.al. Anal. Bioanal. Chem. 387 (2007) 2863–2870; Algarni, S. A. et.al. Talanta 153 (2016) 107–110]. We therefore recommend ‘rough guide’ evanescent wave optrodes, in combination with sensitive ‘light balance’ detector, to succeed membrane- embedding of colorimetric sensitisers such as metalloporphyrines.

Photoluminescence spectra of thin films of ZnTPP–C60 and CuTPP–C60 molecular complexes

The results of studies of thin composite films of zinc and copper tetraphenylporphyrins with different fractions of fullerene C60 are reported. The photoluminescence spectra are recorded, and the composition and surface morphology are analyzed by means of scanning electron microscopy. The results show a difference in the structure of films with two types of metals (Zn, Cu) entering into the complex of the porphyrin macrocycle. An additional long-wavelength photoluminescence band at 1.4 eV is detected for the first time, which is evidence of the formation of ZnTPP–C60 molecular complexes from a gas-dynamic vapor flow upon condensation. In CuTPP thin films, the processes of self-assembly into nanowires 20 nm in diameter and up to 50 µm in length and the formation of nanoheterojunctions upon the addition of fullerene C60 are observed. Quantum-chemical calculations in the context of density-functional theory are carried out to interpret the experimental data.

Polyester fabric coated with Ag/ZnO composite film by magnetron sputtering

Ag/ZnO composite film was successfully deposited on polyester fabric by using direct current (DC) magnetron sputtering and radio frequency (RF) magnetron reaction sputtering techniques with pure silver (Ag) and zinc (Zn) targets. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to examine the deposited film on the fabric. It was found that the zinc film coated on Ag film before RF reactive sputtering could protect the silver film from oxidation. Anti-ultraviolet property and antistatic property of the coated samples using different magnetron sputtering methods were also investigated. The experimental results showed that Ag film was oxidized into in Ag2O film in high vacuum oxygen environment. The deposition of Zn film on the surface of the fabric coated with Ag film before RF reactive sputtering, could successfully obtained Ag/ZnO composite film, and also generated structural color on the polyester fabric.

Electrochemical Rectification of Redox Mediators Using Porphyrin-Based Molecular Multilayered Films on ITO Electrodes.

Electrochemical charge transfer through multilayer thin films of zinc and nickel 5,10,15,20-tetra(4-ethynylphenyl) porphyrin constructed via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry was examined. Current rectification toward various outer-sphere redox probes is revealed with increasing numbers of layers, as these films possess insulating properties over the neutral potential range of the porphyrin, then become conductive upon reaching its oxidation potential. Interfacial electron transfer rates of mediator-dye interactions toward [Co(bpy)3](2+), [Co(dmb)3](2+), [Co(NO2-phen)3](2+), [Fe(bpy)3](2+), and ferrocene (Fc), all outer-sphere redox species, were measured by hydrodynamic methods. The ability to modify electroactive films' interfacial electron transfer rates, as well as current rectification toward redox species, has broad applicability in a number of devices, particularly photovoltaics and photogalvanics.

PVD법에 의해 제작한 Al-Mg 코팅 강판의 내식성에 미치는 Mg 함량 및 열처리의 영향

This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of <TEX>$400^{\circ}C$</TEX> for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as <TEX>$Al_3Mg_2$</TEX> and <TEX>$Al_{12}Mg_{17}$</TEX> were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.

Characterization of ZnO Thin Films Prepared by Thermal Oxidation of Zn

Zinc oxide thin films were prepared by thermal oxidation of zinc films at a temperature of 500°C for 2 h. The Zn films were deposited onto glass substrates by magnetron RF sputtering. The sputtering time varied from 2.5 min to 15 min. The physico-chemical characterization of the ZnO films was carried out depending on the Zn sputtering time. According to x-ray diffraction, ZnO films were polycrystalline and the Zn-ZnO phase transformation was direct. The mean transmittance of the ZnO films was around 80% and the band gap increased from 3.15 eV to 3.35 eV. Photoluminescence spectra show ultraviolet, visible, and infrared emission bands. The increase of the UV emission band was correlated with the improvement of the crystalline quality of the ZnO films. The concentration of native defects was found to decrease with increasing Zn sputtering time. The decrease of the electrical resistivity as a function of Zn sputtering time was linked to extrinsic hydrogen-related defects.