共查询到20条相似文献,搜索用时 203 毫秒
1.
Irena Lj. Arsova Abdurauf R. Prusi Ljubomir D. Arsov 《Journal of Solid State Electrochemistry》2003,7(4):217-222
Anodic oxide films formed potentiostatically on niobium surfaces, from open circuit potential (OCP) to 10 V, were studied
by performing in situ and ex situ ellipsometric measurements. The kinetics of the film thickness growth in 1 M H2SO4 and complex indices of refraction of these films were determined. A strong influence of the surface preparation conditions
on the complex refractive indices of the metal substrate and anodic oxide films was shown. By steady-state measurements at
OCP, a small thickening of the natural air-formed oxide film with chemical composition Nb2O5 in 1 M H2SO4 solution was detected. With cathodic pre-treatment, only partial reduction and small thinning of the natural air-formed oxide
film was possible. The thicknesses of the natural air-formed oxide films on fine mechanically polished and electropolished
Nb surfaces were determined. The build up of the natural air-formed oxide film, at ex situ conditions, on the already formed
anodic oxide films was confirmed. It was shown that electropolishing gives more similar optical surface properties to the
bare metal than the fine mechanical polishing.
Electronic Publication 相似文献
2.
The possibility of forming niobium oxynitride through the nitridation of niobium oxide films in molecular nitrogen by rapid
thermal processing (RTP) was investigated. Niobium films 200 and 500 nm thick were deposited via sputtering onto Si(100) wafers
covered with a thermally grown SiO2 layer 100 nm thick. These as-deposited films exhibited distinct texture effects. They were processed in two steps using an
RTP system. The as-deposited niobium films were first oxidized under an oxygen atmosphere at 450 °C for various periods of
time and subsequently nitridated under a nitrogen atmosphere at temperatures ranging from 600 to 1000 °C for 1 min. Investigations
of the oxidized films showed that samples where the start of niobium pentoxide formation was detected at the surface and the
film bulk still consisted of a substoichiometric NbOx phase exhibited distinctly lower surface roughness and microcrack densities than samples where complete oxidation of the
film to Nb2O5 had occurred. The niobium oxide phases formed at the Nb/substrate interface also showed distinct texture. Zones of niobium
oxide phases like NbO and NbO2, which did not exist in the initial oxidized films, were formed during the nitridation. This is attributed to a “snow-plough
effect” produced by the diffusion of nitrogen into the film, which pushes the oxygen deeper into the film bulk. These oxide
phases, in particular the NbO2 zone, act as barriers to the in-diffusion of nitrogen and also inhibit the outdiffusion of oxygen from the SiO2 substrate layer. Nitridation of the partially oxidized niobium films in molecular nitrogen leads to the formation of various
niobium oxide and nitride phases, but no indication of niobium oxynitride formation was found.
Figure Schematic representation of the phase distribution in 200 nm Nb film on SiO2/Si substrate after two steps annealing using an RTP system. The plot below represents the SIMS depth profiles of the nitridated
sample with the phase assignment 相似文献
3.
UV-Vis and Raman Spectral Analysis of Polyaniline/Gold Thin Films as a Function of Applied Potential
《Analytical letters》2012,45(7):1206-1216
Polyaniline and polyaniline/gold films were prepared by potentiodynamic oxidation of aniline in 1 M H2SO4 aqueous solution, and their electrochromic properties were investigated by UV-Vis and Raman spectroscopy. Both tetrachloroaurate and gold nanoparticles were used to deposit gold onto or inside the polyaniline film based on the deposition technique used. Polyaniline films showed multiple color changes (blue to green to yellow) depending on the electrochemical reactions in the potential range ?0.2 to 0.8 V vs. Ag/AgCl. The color of polyaniline films changed from transparent green to yellow at the anodic peak around 0.2 V and gradually changed from green to dark blue at potentials higher than 0.5 V. The deterioration of electrochromic properties is caused by hydrolysis of the diimine structure formed by oxidation at 0.8 V. Furthermore, the polyaniline films showed enhanced Raman characteristics (due to SERS) depending on the treatments with gold and the potentials applied to the films to control the oxidation state. 相似文献
4.
Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated
by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating
agent and thiourea as sulfur source. The resulting S-doped Nb2O5 nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy
(EDAX), scanning electron microscope (SEM), ultra-violet diffuse reflectance (UV-DRS) and thermogravimetry thermal Analysis
(TG-DTA). As against the response of unmodified niobium(V) oxide nanoparticles (UNON), the doped samples show different electrochemical
response indicating an induced charge transfer across the niobium pentoxide/solution interface, thus forming two anodic peaks
and a cathodic peak. This important observation was confirmed by UV-DRS in terms of band bending due to sulfur doping. Upon
sulfur-modification, the absorption edge extends into the visible light region. The SEM observation shows that the SNPN existed
in the mode of polycrystalline structure and the average grain size 63 nm. The EDAX analysis of undoped Nb2O5 and sulfur doped Nb2O5 shows the Nb2O5 (98%) and S (2%) content of nanopowder. These SNON nanoparticles are expected to be suitable candidates as visible light
niobium(V) oxide nanoparticles sensitization. 相似文献
5.
Bożena Pilarek Aleksandra J. Pelczarska Irena Szczygieł 《Journal of Thermal Analysis and Calorimetry》2017,130(1):77-83
The characterization of three commercial powders of niobium(V) oxide received from two producers was made. The thermal behavior of Nb2O5 up to melting point and its microstructure were studied using X-ray powder diffraction, thermoanalytical methods (DSC/TG), infrared spectroscopy (IR) and scanning microscopy. Analysis of the obtained results revealed that the starting structure of niobium(V) oxide and its thermal behavior depend on the origin of niobia. Depending on the origin of the powder and of its thermal treatment, three polymorphs of Nb2O5 can be observed. Sintering of powders above 1200 °C results in the formation of single phase, H-Nb2O5. 相似文献
6.
Mark Röscher Theodor Schneller Rainer Waser 《Journal of Sol-Gel Science and Technology》2010,56(3):236-243
The impact of chemical precursor modification on the electronic properties of chemical solution deposition derived niobium
oxide thin-films has been evaluated. It has been found that the application of certain chemical modifications is mandatory
in order to obtain electrically insulating thin-films at low processing temperatures. It is emphasized that the devised optimal
way of processing for the niobium component is widely contrary to the solution based processing of potassium sodium niobate
films reported so far. Regarding the physical nature of the observed instabilities, the phase evolution of solution processed
niobium oxide films has been studied. It has been detected that the organic fraction in the precursor solution is stable up
to high temperatures and as a result, the low temperature crystalline TT-phase of niobium oxide is preserved up to unusually
high processing temperatures. The inherent structural distortion of the unit cells may present a new defect mechanism that
has to be further investigated regarding the inferior ferroelectric properties of chemical solution derived potassium sodium
niobate thin-films, which are often observed. 相似文献
7.
Three-dimensionally ordered macroporous (3-DOM) niobium oxide was fabricated by aqueous organic gel method through the interstitial spaces between polystyrene spheres assembled on glass substrates. Freshly precipitated hydrous niobium oxide (Nb2O5·nH2O), which was prepared starting from Nb2O5, was used in combination with citric acid in an aqueous solution and then was transferred as a niobium source to synthesize 3-DOM Nb2O5. The morphologies of porous Nb2O5 were characterized by scanning electron microscope (SEM). The thermal decomposition and phase composition of 3-DOM Nb2O5 were investigated by Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric–differential thermal analysis (TG–DTA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). 相似文献
8.
Maria J. S. Serafím Karl E. Bessler Sebastião S. Lemos Maria J. A. Sales Javier Ellena 《Transition Metal Chemistry》2007,32(1):112-116
Three oxoniobium(V) complexes ONbL3 with HL = tropolone (1), 2-pyridinol-N-oxide (2) or, 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (3) are obtained in good yield by one step reactions from commercially available hydrated niobium(V) oxide in aqueous media.
The products are characterized by elemental analysis, FT-IR spectroscopy, NMR spectroscopy (1H- and 13C-) and thermogravimetry. The crystal structure of oxotris(2-pyridinolato-N-oxide)niobium(V) is determined by single crystal X-ray diffraction, showing discrete molecules with pentagonal bipyramidal
coordinated niobium. The 1H-NMR spectra of CDCl3 solutions indicate a fluxional behaviour for the three complexes. 相似文献
9.
Yung-Sen Lin Di-Jiun Lin Lu-Yan Chiu Sheng-Wei Lin 《Journal of Solid State Electrochemistry》2012,16(8):2581-2590
Reversible lithium intercalation and deintercalation behavior of atmospheric pressure plasma jet (APPJ)-synthesized organonickel oxide (NiO x C y ) thin films under various substrate distances is testified in an electrolyte (1?M LiClO4–propylene carbonate solution) at low driving voltages from ?0.5 to 1.5?V. Fast responses of 2?s bleaching at ?0.5?V and 6?s coloration at +1.5?V are accomplished for the nano-porous NiO x C y thin films. This study reveals that a rapid synthesis of electrochromic NiO x C y thin films in a single process via APPJ by 21?s is investigated. This study presents a noteworthy electrochromic performance in a light modulation with up to 43% of transmittance variation and a coloration efficiency of 36.3?cm2/C at a wavelength of 830?nm after 200?cycles of cyclic voltammetry measurements. 相似文献
10.
Yu.A. Buslayev E.G. Ilyin M.E. Ignatov L.S. Butorina T.A. Mastryukova 《Journal of fluorine chemistry》1978,12(5):387-395
19F NMR and i.r. spectroscopy were employed to study complex formation of niobium and tantalum pentafluorides with triphenylphosphine oxide, ethyl diphenylphosphinate and S-ethyl diphenylthiophosphinate in methylene chloride and in acetonitrile. In methylene chloride solution MF5L, M2FIOL, MF4L2+ and M2FII? complexes were found (M=Nb, Ta;L- phosphoryl-containing Ligand). I.r. frequencies are assigned. Solvent properties (electric conductivity and donor capacity) affect the relative stability of complexes. The dependence of 19F NMR parameters on the donor capacity of the ligands is discussed. 相似文献
11.
M. Sunada H. Takahashi T. Kikuchi M. Sakairi S. Hirai 《Journal of Solid State Electrochemistry》2007,11(10):1375-1384
Highly pure aluminum specimens (99.99%) after electropolishing and DC-etching were covered with SiO2 films by electrophoretic sol-gel coating and were anodized in neutral boric acid/borate solutions. Time-variations in cell
voltage during electrophoretic sol-gel coating and in anode potential during anodizing were monitored. Structure and dielectric
properties of the anodic oxide films were examined by scanning electron microscopy (SEM), transmission electron microscopy
(TEM), energy-dispersive X-ray (EDX), and electrochemical impedance spectroscopy (EIS). It was found that electrophoretic
sol-gel coating forms uniform SiO2 films on the surface of both electropolished and DC-etched specimens. Anodizing of specimens after electrophoretic coating
lead to the formation of anodic oxide films consisting of two layers: an inner alumina layer and an outer Al–Si composite
oxide layer. The anodic oxide films formed, thus, had slightly higher capacitances than those formed on aluminum without any
coating. Higher heating temperatures after electrophoretic deposition caused the increase in capacitance of anodic oxide films
more effectively. Anodizing in a boric acid solution after SiO2 coating on DC-etched foil allowed the anode potential to reach a value higher than 1,000 V, resulting in 39% higher capacitances
than those on specimens without SiO2 film.
Dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday. 相似文献
12.
M. Ejaz 《Journal of Radioanalytical and Nuclear Chemistry》1975,27(1):67-75
The distribution of tantalum(V) between 0.1M trioctylamine oxide dissolved in xylene and sulphuric acid solutions has been studied. On the basis of results on the distribution, it is concluded that at sulphuric acid concentration 0.5M, tantalum is probably extracted by a solvate mechanism as the complex Ta(OH) (SO4)2·3TOAO. It has also been shown that tantalum can be quantitatively separated from niobium, uranium, thorium and rare earth elements by extraction with N-oxide of trioctylamine from 0.5M sulphuric acid solution. 相似文献
13.
Jin-Young Park Kwang-Soon Ahn Yoon-Chae Nah Hee-Sang Shim Yung-Eun Sung 《Journal of Sol-Gel Science and Technology》2004,31(1-3):323-328
Nickel oxide thin films, which are well known anodic coloration materials that are used in electrochromic devices, were prepared by a sol–gel method, and their electrochemical and electrochromic properties were investigated. The sol was prepared from Ni(OH)2 powder with an average size of 7 nm, in a mixture of ethylene glycol and absolute ethanol. The films were coated on an ITO substrate using the powder, dispersed in the solution. When additive materials, acetyl acetone and glycerol, were added to the sol its hardness and adhesion properties were improved. The optimized thin film formed an amorphous, porous structure, and showed a large current density during continuous potential and pulse potential cycling. The film also was transparent and had a high coloration efficiency (33.5 cm2/C) and a rapid response time (1.0–2.5 s) during the coloring/bleaching process. 相似文献
14.
The extraction of niobium(V) in the form of a chloro complex has been studied. Radiometrical and spectrophotometrical studies show that niobium(V) is extracted practically completely from a solution containing more than 9 mol dm?3 chloride in the range of 2–5 M hydrogen ion concentration by chloroform solutions of tetraphenylarsonium (TPA) and tetraphenylphosphonium (TPP) chloride and that niobium is not extracted at chloride concentrations less than 6 mol dm?3. The mechanism of extraction is based on the formation of the ion-associated compounds that form between the onium cation and the oxotetra-chloroniobate(V) anion. The extracted complexes in chloroform have a maximum absorbance at 282 nm (TPA) and 285 nm (TPP); they obey Beer's law in the range of 1–10 μg Nb ml?1, and are stable for at least 24 hr. The molar absorptivity of the method is 1.33 × 104 dm3 mol?1cm?1. The composition of the extracted species [(C6H5)4X] [NbOCl4] where X = As or P was determined spectrophotometrically, radiometrically, and by characterization of the crystalline compounds isolated. 相似文献
15.
Norma R. de Tacconi Krishnan Rajeshwar Reynaldo O. Lezna 《Journal of Electroanalytical Chemistry》2001,500(1-2)
The voltammetric and electrochromic behavior of two types of indium(III) hexacyanoferrate(II/III) (InHCF) films, potentiodynamically grown either on polycrystalline Au or on tin-doped indium oxide (ITO) support electrodes, are described. A new spectral feature was seen at ca. 475 nm for the InHCF films grown on Au under extended potential window (EPW) conditions, in addition to the dominant 420 nm feature described by previous authors. The 420 nm band is the sole electrochromic feature in films grown under restricted potential window (RPW) conditions. The InHCF films were also grown in the presence of TiO2 particles in the deposition bath. The resultant InHCF–TiO2 composite films showed distinctly different photoelectrochemical responses for the EPW and the RPW counterparts. X-ray phoelectron spectroscopy data showed a higher TiO2 particle uptake for the EPW films relative to their RPW counterparts, under otherwise identical growth conditions. A second film configuration built up by InHCF derivatization of a pre-formed In–TiO2 film, yielded decidedly inferior photoresponses. Mechanistic reasons for this are presented as is evidence for the dominance of two distinct forms of InHCF under the EPW growth conditions. 相似文献
16.
V. G. Maiorov A. I. Nikolaev V. K. Kopkov V. Ya. Kuznetsov N. L. Mikhailova 《Russian Journal of Applied Chemistry》2011,84(7):1137-1140
Alkaline niobium(V) solutions containing up to 190 g l−1 of niobium oxide were prepared by sintering niobium(V) oxide with potassium carbonate and following leaching of the sinters
with water. 相似文献
17.
Lin Yung-Sen Chen Hsuan-Ta Wu Siang-Syuan 《Journal of Solid State Electrochemistry》2010,14(10):1885-1895
An investigation was conducted into the electrochromic properties of organotungsten oxide WO
x
C
y
films synthesized onto 60 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates using low temperature, plasma-enhanced
chemical vapor deposition (PECVD) at varying oxygen concentrations. The PECVD-synthesized WO
x
C
y
films were proven to offer remarkable electrochromic performance. Cyclic voltammetry switching measurements revealed that
only low driving voltages from −1 to 1 V are needed to provide reversible Li+ ion intercalation and de-intercalation in a 0.1 M LiClO4–PC electrolyte. Light modulation with transmittance variation of up to 72.9% and coloration efficiency of 62.5 cm2/C at a wavelength of 650 nm was obtained. 相似文献
18.
Photocurrents emerging during the formation of anodic oxide films (AOF) on such valve metals as W, Ti, Zr, Nb, Ta are measured
during an increase (direct run) and a decrease (reverse run of voltammetric curves) in the anodic potential. Capacitances
of AOF formed at certain potentials are measured at potentials below the AOF formation potential. Effect of semiconductor
properties on the AOF growth is considered through the formation of a Schottky barrier at the oxide/electrolyte interface.
Calculated thicknesses of AOF and the depleted layer are compared. The donor-concentration drop in AOF with the distance from
the metal/oxide interface is a condition for the growth of thick semiconductor oxide films. The measured potential dependence
of the semiconductor-film capacitance is used to plot the donor concentration drop as a function of the distance from the
Nb2O5/Nb interface in the oxide layer on a niobium electrode.
Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth. 相似文献
19.
Maciej Sowa Alicja Kazek-Kęsik Agnieszka Krząkała Robert P. Socha Grzegorz Dercz Joanna Michalska Wojciech Simka 《Journal of Solid State Electrochemistry》2014,18(11):3129-3142
Herein, a study of the plasma electrolytic oxidation (PEO) of niobium in an anodising bath composed of potassium silicate (K2SiO3) and potassium hydroxide (KOH) is reported. The effects of the K2SiO3 concentration in the bath and the process voltage on the characteristics of the obtained oxide layers were assessed. Compact, barrier-type oxide layers were obtained when the process voltage did not exceed the breakdown potential of the oxide layer. When this threshold was breached, the morphology of the oxide layer changed markedly, which is typical of PEO. A significant amount of silicon, in the form of amorphous silica, was incorporated into the oxide coatings under these conditions compared with the amount obtained with conventional anodising. This surface modification technique led to an improvement in the corrosion resistance of niobium in Ringer’s solution, regardless of the imposed process conditions. 相似文献
20.
E. V. Rakhmanov Zhong Sinyan A. V. Tarakanova A. V. Anisimov A. V. Akopyan N. S. Baleeva 《Russian Journal of General Chemistry》2012,82(6):1118-1121
Synthesis of four niobium sandwich peroxo complexes containing fragments of substituted indenes was performed and their structure was proved by NMR spectroscopy and ESI-MS mass spectrometry. Catalytic activity of the complexes in the oxidation of sulfides with hydrogen peroxide was studied, and a high selectivity in the oxidation of sulfides to sulfoxides and sulfones of the sandwich peroxo complexes was found. 相似文献