Search results for "Anodizing"
showing 10 items of 116 documents
Anodic oxide films on tungsten—II. The morphology and dissolution of the films
1980
Abstract Scanning electron microscopy was used to investigate the morphology of anodic oxide films on tungsten, obtained in various conditions of anodization. Studies were made of the growth of porous films, whose thickness increases with time and depends upon the current density. Temperature and electrolyte composition influence the film morphology. Gravimetric measurements of film dissolution at 70°C show that after a transient time, the rate of metal dissolution and that of film formation coincide. The porous films thicken because tungsten dissolves as WO 2 2+ and precipitates as WO 3 .H 2 O.
Conductive films of ordered nanowire arrays
2004
peer-reviewed High-density, ordered arrays of germanium nanowires have been synthesised within the pores of mesoporous thin films (MTFs) and anodized aluminium oxide (AAO) matrices using a supercritical fluid solution-phase inclusion technique. Conductive atomic force microscopy (C-AFM) was utilised to study the electrical properties of the nanowires within these arrays. Nearly all of the semiconductor nanowires contained within the AAO substrates were found to be conducting. Additionally, each individual nanowire within the substrate possessed similar electrical properties demonstrating that the nanowires are continuous and reproducible within each pore. C-AFM was also able to probe the co…
Photoelectrochemical evidence of inhomogeneous composition at nm length scale of anodic films on valve metals alloys
2016
Abstract Anodic films of different thickness (∼30 nm and 70 nm) were grown by anodizing sputtering-deposited Ta-19at% Al to different formation voltages. N incorporation into the anodic films was inducing by performing the anodizing process in ammonium containing solutions. Layered anodic films were prepared by a double formation procedure with a first anodizing step in ammonium biborate solution and second anodizing step in borate buffer solution, or vice versa. Glow Discharge Optical Emission Spectroscopy was employed to show the distribution of N across the oxide. Photoelectrochemical measurements evidenced a red shift of the light absorption threshold due to N incorporation. A model was…
Plasma Electrolytic Oxidation of TiZr Alloy in ZnONPs-Contained Solution: Structural and Biological Assessment
2020
Titanium (Ti) and its alloys with zirconium (Zr) due of their biological safety, lower elastic modulus and excellent corrosion resistance are the most attractive metallic materials for medical applications. Plasma electrolytic oxidation (PEO) is an environment-friendly process with rapid deposition of anodic oxide coating on the implant surface. PEO coating can incorporate different nanoparticles (NPs) into implant surface such as ZnO that stimulates osteoblast proliferation and mineralization, possesses antibacterial ability. The aim of current research was to evaluate structural and chemical properties of TiZr-alloy with addition ZnO NPs after the PEO in Ca/P solution. The alloy of the Ti…
Cathodoluminescence characterization of ZnO/ZnS nanostructures anodized under hydrodynamic conditions
2018
[EN] ZnO/ZnS nanostructures were successfully synthesized by a simple electrochemical anodization of zinc in a glycerol based electrolyte containing sulfide-ammonium fluoride. The influence of different hydrodynamic conditions and anodization potentials during anodization on the morphological and electronic properties of the obtained ZnO/ZnS nanostructures was studied. The anodized samples were characterized using confocal Raman microscopy, X-Ray Diffraction (XRD), Field Emission Scanning Electronic Microscopy (FE-SEM), cathodoluminescence (CL), and photoelectrochemical water splitting tests under standard AM 1.5 conditions. The results showed that hydrodynamic conditions and higher potenti…
Investigation of Critical Points of Pore Formation Voltage on the Surface of Semiconductors of A3B5 Group
2021
In this work, critical values of pore-formation in electrochemical machining of semiconductors of A 3 B 5 group are studied. On the example of indium phosphide, the indicators of the series of dependence of current density on the voltage of anodization are studied. The rates of current density increase in the regime of gradual rise of anodization voltage are determined. According to these indicators, the intervals are established, within which the active pore-formation occurs on the surface of semiconductor.
Optimization of anodizing process of tantalum for Ta2O5-based capacitors
2020
Anodic oxides were grown to 50 V on Ta in several organic ions containing anodizing baths. Their properties were compared with anodic Ta oxide film grown to the same formation voltage in 0.1 M NaOH. Anodizing process carried out in sodium citrate led to the growth of the anodic oxide with the best blocking properties whilst, when Ta is anodized in sodium adipate, a significant part of the circulated charge is wasted in side reactions, such as oxygen evolution. Photoelectrochemical measurements showed the presence of optical transitions at energy lower than the band gap for the anodic films grown in citrate and tartrate electrolytes, attributed to localized electronic states located close to…
ZnO/ZnS heterostructures for hydrogen production by photoelectrochemical water splitting
2016
This work studies the photoelectrochemical behavior of novel ZnO/ZnS heterostructures obtained by means of anodization in water and glycerol/water/NH4F electrolytes with different Na2S additions under controlled hydrodynamic conditions. For this purpose different techniques such as Field Emission Scanning Electronic Microscopy (FE-SEM) with EDX, Raman spectroscopy and photoelectrochemical water splitting tests under standard AM 1.5 conditions have been carried out. The obtained results showed that the hydrodynamic conditions promoted an ordered nanotubular morphology which facilitates electron-hole separation and consequently, the photoelectrochemical activity for water splitting is enhance…
High-Density Plasmonic Nanoparticle Arrays Deposited on Nanoporous Anodic Alumina Templates for Optical Sensor Applications
2019
This study demonstrates a new, robust, and accessible deposition technique of metal nanoparticle arrays (NPAs), which uses nanoporous anodic alumina (NAA) as a template for capillary force-assisted convective colloid (40, 60, and 80 nm diameter Au) assembly. The NPA density and nanoparticle size can be independently tuned by the anodization conditions and colloid synthesis protocols. This enables production of non-touching variable-density NPAs with controllable gaps in the 20&ndash
Novel tree-like WO3 nanoplatelets with very high surface area synthesized by anodization under controlled hydrodynamic conditions
2016
In the present work, a new WO3 nanostructure has been obtained by anodization in a H2SO4/NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disk Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FESEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area exposed to the electrolyte, leading to an outstanding enhancement of its photoelectrochemical activity. Obtained results show that the size of nanostructures and the percentage of electrode surface covered by…