共查询到20条相似文献,搜索用时 31 毫秒
1.
R. Cremer Mirjam Witthaut Alexander von Richthofen Dieter Neuschütz 《Analytical and bioanalytical chemistry》1998,361(6-7):642-645
Structural transitions of metastable Ti1–xAlxN coatings on technically relevant substrates were determined as a function of the Ti/Al ratio. Ti1–xAlxN films with different Ti/Al ratios were deposited on high speed steel (HSS) substrates at substrate temperatures of 300?° and 500?°C by means of reactive magnetron sputtering ion plating (MSIP). A Ti/Al compound target was used as well as a cluster arrangement of one Ti and one Al target for comparison. The composition of the films was determined by electron probe microanalysis (EPMA), the crystallographic structure by thin film X-ray diffraction (XRD). The analyses revealed that films deposited with Ti/Al ratios of 44/56 and 36/64 had grown in cubic NaCl structure, a film with a Ti/Al ratio of 32/68 was two-phase, and a Ti/Al ratio of 25/75 led to a hexagonal film in wurtzite structure. Only small differences of the lattice parameters could be observed in dependence of temperature: At 300?°C the lattice parameters of the cubic structure corresponded exactly to Vegard‘s law, whereas they slightly decreased in the films deposited at 500?°C. The application of a cluster arrangement instead of a compound target resulted in nearly the same lattice parameters and peak shapes. 相似文献
2.
X. J. Zhang Q. Li S. Y. Zhao C. X. Gao Z. G. Zhang 《Journal of Sol-Gel Science and Technology》2008,47(1):107-114
Al2O3/ZrO2 duplex films were deposited on a γ-TiAl based alloy by sol–gel processing starting from aluminum isopropoxide (Al(OC3H7)3) and zirconium (IV) oxychloride octahydrate (ZrOCl2 · 8H2O) as raw materials. Isothermal oxidation at 900 and 1,000 °C in 0.1 MPa O2 and cyclic oxidation at 1,000 °C in air of the coated and uncoated specimens were performed to investigate the effect of
the duplex films on the oxidation behavior of the γ-TiAl alloy. The results of the isothermal oxidation tests indicated that
the parabolic rate constants of the alloy were decreased due to the applied thin film. Additionally, the present film exhibited
a beneficial effect on the cyclic oxidation resistance of the alloy in air. The duplex film could restrain the growth of TiO2, causing an increase of the Al2O3 content in the oxide mixture and thus decreased the oxidation rate. 相似文献
3.
Ti(C, N) based materials represent a new class of hard and wear resistant structural materials. Nowadays, the main field
of applications is focused on metal cutting and finishing operations. For these kinds of applications usually the mentioned
materials work in oxidizing environments at high temperatures. The thermophysical stability under these conditions represents
therefore a key factor that influences the material’s performance, and consequently the tool life of the component in service.
The present study aimed to investigate the oxidation behaviour of two different Ti(C, N)-WC based materials, the first containing
0.9 wt% of Co and the second 6.2 wt% of Ni and 2.9 wt% of Co. Cycled oxidation tests (20 hours each) were conducted with a
muffle furnace in laboratory static air at 1000 °C up to 100 hours. During the initial transitory stage the competition between
the mass gain due to the formation of solid TiO2 (rutile) and the mass loss due to released volatile W oxides controlled the mass change; thereafter the oxidation process
obeyed a linear law. Great microstructural modifications occurred on the (sub)surfaces of the oxidized samples: multiphase
TiO2 based scales grew upon the external surfaces of the oxidized specimens. Kinetics and oxidation mechanisms were proposed and
discussed. 相似文献
4.
Fran?ois DelaunayRID=""ID="" To whom correspondence should be addressed Claire Berthier Michel Lenglet Jean-Michel Lameille 《Mikrochimica acta》2000,132(2-4):337-343
The oxidation in air under isothermal conditions of Inconel 718 has been investigated at 900 °C. We have studied the firsts
stages of the high temperature oxidation mechanism. The oxidised samples were examined using a number of surface analytical
techniques including XPS and SEM-EDS. The results have shown that minor alloying elements strongly influence the oxidation
behaviour of the alloy:
Previous studies had shown that the rate of the external oxide scale growth and the intergranular oxide penetration during
oxidation of Inconel 718 at 900 °C in air are lower than those of Inconel X or Incoloy 800. We suggest that the formation
of a quasi continuous scale of the intermetallic phase Ni3Nb at the oxide-alloy interface could have an important contribution to the good oxidation resistance of Inconel 718. 相似文献
5.
Quantitative quadrupole mass spectrometry of (Ti, W)C-based cemented carbonitrides was carried out in order to monitor the
evolution of the gas species as a function of time and temperature during vacuum sintering. Solid standards and gas mixtures
as well as precise flow control were employed for calibration. Upon integration of the outgassing rates the carbon and nitrogen
evolutions and mass losses during sintering of raw hardmetal powder mixtures (WC, TiC,…) and cemented carbonitrides could
be quantified. Outgassing occurs in the range of temperatures 490–1480 °C. Nitrogen outgassing of (Ti, W)(C, N) was greater
than that of Ti(C, N) due to the presence of W which increases the nitrogen activity in the solid causing a higher nitrogen
equilibrium pressure. TiN showed a CO (0.2 wt%) and N2 (0.5 wt%) weight loss only in the presence of the binder phase. For powder mixtures, it was observed that the amount of CO,
CO2 and N2 liberated during vacuum sintering increased with the addition of cobalt in comparison with the same powders without binder
phase. Nitrogen containing cermet alloys showed a greater loss of carbon than (Ti, W)C-based hardmetals. A careful control
of carbon content by doping seems to be necessary in such alloys to avoid η-phase formation.
Received July 7, 2000. Revision December 4, 2000. 相似文献
6.
M. Witthaut Rainer Cremer Alexander von Richthofen Dieter Neuschütz 《Analytical and bioanalytical chemistry》1998,361(6-7):639-641
The oxidation behavior of cubic Ti1-xAlxN films was improved by decreasing the Ti/Al ratio from 50/50 in the direction of the phase transition between cubic and hexagonal structure. Metastable, polycrystalline, single-phase Ti1-xAlxN films were deposited on high speed steel (HSS) substrates by reactive magnetron sputtering ion plating (MSIP). The composition of the bulk was determined by electron probe microanalysis (EPMA), the crystallographic structure by thin film X-ray diffraction (XRD). A Ti1-xAlxN film with a Ti/Al atomic ratio of 38/62 was deposited in cubic NaCl structure, whereas a further decrease of the Ti/Al ratio down to 27/73 led to a two-phase film with both cubic and hexagonal constituents. The Ti0.38Al0.62N film was oxidized in synthetic air for 1 h at 800?°C. The oxidic overlayer was analyzed by X-ray photoelectron spectroscopy (XPS) sputter depth profiling, EPMA crater edge linescan analysis, and secondary neutrals mass spectroscopy (SNMS). Scanning electron microscopy (SEM) micrographs of the cross sectional fracture were taken for morphological examination. With higher Ti content, the Ti1-xAlxN formed a TiO2-x rich sublayer beneath an Al2O3 rich toplayer, whereas the oxide layer on the Ti0.38Al0.62N film consisted of pure Al2O3. The thickness of the oxide layer was determined to 60–80 nm, about a quarter of the oxide layer thickness detected on Ti0.5Al0.5N films. The absence of a TiO2-x sublayer was also confirmed by XRD. The results show a distinct improvement of the oxidation resistance of cubic Ti1-xAlxN films by increasing the Al content from x = 0.5 to 0.62, whereas a further increase leads to the hexagonal structure, which is less suitable for tribological applications due to its tendency to form cracks during oxidation. 相似文献
7.
Betul Akkopru Akgun Nathan P. Mellott Caner Durucan 《Journal of Sol-Gel Science and Technology》2012,62(2):240-251
Silver containing silica (Ag–SiO2) thin films with and without aluminum (Al) were prepared on soda-lime-silica glass by spin coating of aqueous sols. The coating
sol was formed through mixing tetraethyl orthosilicate [Si(OC2H5)4]/ethanol solution with aqueous silver nitrate (AgNO3) and aluminum nitrate nonahydrate [(AlNO3)3·9H2O] solutions. The deposited films were calcined in air at 100, 300 and 500 °C for 2 h and characterized using x-ray diffraction,
UV-visible and x-ray photoelectron spectroscopy. The effect of Al incorporation and calcination treatment on microstructure
and durability of the films, and chemical/physical state of silver in the silica thin film have been reported. The bactericidal
activity of the films was also determined against Staphylococcus aureus via disk diffusion assay studies before and after chemical durability tests. The investigations revealed that the optical,
bactericidal properties and chemical durability of Ag–SiO2 films can be improved by Al addition. The Al-modified Ag–SiO2 thin films do not exhibit any coloring after calcination in the range of 100–500 °C, illustrating that silver is incorporated
within the silica gel network in ionic form (Ag+). Al incorporation also improved the overall durability and antibacterial endurance of Ag–SiO2 thin films. 相似文献
8.
Influence of thermal annealing on the microstructure,hardness and corrosion behavior of TiAlSiCuN nanocomposite films 下载免费PDF全文
J. Shi M. Q. Wan H. L. Wang X. Wang T. ‐G. Wang 《Surface and interface analysis : SIA》2016,48(12):1310-1315
Nanocomposite TiAlSiCuN films were deposited on high speed steels by filtered magnetic arc ion plating. Detailed properties of the films annealed at various temperatures are studied. After thermal annealing at different temperatures ranging from 400 to 800 °C, changes in the film micro‐structure, chemical and phase composition, surface morphology, hardness and polarization curve properties were systematically characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, nano‐indenter and electrochemical workstation, respectively. It was found that the TiAlSiCuN films could be fully oxidized at 800 °C, Al and Ti atoms all diffused outwards and formed dense protective Al2O3 and TiO2 layer. Simultaneously, the TiAlN phase gradually disappeared. The films annealed at 400 °C obtained the highest hardness because of the certain grain growth and little generated oxides. Besides, the certain formation of dense protective Al2O3 layer made the TiAlSiCuN film annealed at 600 °C present the least corrosion current density and the corrosion voltage. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
9.
X. J. Zhang S. Y. Zhao C. X. Gao S. J. Wang 《Journal of Sol-Gel Science and Technology》2009,49(2):221-227
Silica coating derived by sol–gel processing was deposited on an orthorhombic phase Ti–22Al–26Nb alloy by dip-coating technique.
Isothermal oxidation at 800 and 900 °C and cyclic oxidation at 900 °C in static air of the coated and uncoated specimens were
performed to investigate the effect of the silica coating on the oxidation behavior of the Ti–22Al–26Nb alloy by thermogravimetry,
SEM and XRD. The average parabolic rate constants of the coated specimens were lower than those of uncoated ones. Additionally,
the present film exhibited a beneficial effect on the cyclic oxidation resistance of the alloy in air. TiO2, Nb2TiO7 or AlNbO4 were the main phases formed on the alloy. The thin film could inhibit the growth of the oxides. The possible mechanism of
the thin film on the oxidation behavior of the alloy was discussed. 相似文献
10.
The surface and in-depth compositions of sputter-deposited Cu0.57Ni0.42Mn0.01 thin films were studied by Auger electron depth profiling after thermal treatment. The samples were thermally cycled to maximum
temperatures of 300 °C to 550 °C in air, argon and forming gas (N2, 5 vol. % H2). Linear least-squares fit to standard spectra and factor analysis were applied to separate the overlapping Auger transitions
of Cu and Ni.
Under bombardment by 4 keV argon ions, CuNi(Mn) layers display bombardment-induced surface enrichment of Ni in the same extent
as binary CuNi alloys. At sufficiently high oxygen partial pressures, a duplex oxide layer is formed and a thick surface copper
oxide overgrows the initial nickel oxide. In reducing atmosphere selective oxidation of manganese takes place.
A capping NiCr layer prevents CuNi(Mn) from being oxidized, but the film configuration is degraded with increasing annealing
temperature due to formation of a surface chromium oxide and diffusion of Ni from the CuNi(Mn) layer into the NiCr/CuNi(Mn)
interface. 相似文献
11.
Thin solid films of mixed Fe/Ti oxide composition (Fe/Ti molar ratios: 0.5∶1, 1∶1, 1.5∶1) have been made from Fe(NO3)3 alcoholic solution to which Ti(OiPr)4 was added. Films have been deposited by the dip-coating technique and heat-treated at 300°C and 500°C. Powders of Fe/Ti oxide
heat-treated at 300°C are amorphous, while powders annealed at 500°C for 40 hours transformed to mixed rutile, pseudobrookite
and hematite phases. The structure of the XRD amorphous films was identified with the help of near-normal reflection absorption
(6°) (IRRA) and near-grazing incidence angle (NGIA) spectroscopy. NGIA FT-IR spectra of films are characterised with a single
phonon mode appearing in the spectral range 600–950 cm−1 which shifts with increasing Ti concentration from 675 cm−1 (Fe2O3) to 904 cm−1 (TiO2) thus exhibiting one-mode behavior.
Electrochemical investigations made with the help of cyclic voltammetry (CV) and chronocoulometry (CPC) performed in 0.01M LiOH and in 1M LiClO4/propylene carbonate electrolytes revealed that films are able to uptake reversibly Li+ ions with a charge capacity (Q) per film thickness (d) in the range 0.1–0.26 mC/cm2nm and 0.06 mC/cm2nm, respectively. The temperature at which the films were prepared alters the rate of Li+ insertion which is faster for less compact films obtained at 300°C. In situ UV-VIS spectroelectrochemical measurements revealed
that Fe/Ti oxide films bleached in the UV spectral region (300 nm<λ<450 nm) and colored in the VIS spectral region (450 nm<λ<800
nm), thus exhibiting mixed anodic and cathodic electrochromism. 相似文献
12.
J. A. Weima A. M. Zaitsev R. Job G. Kosaca F. Blum G. Grabosch W. R. Fahrner J. Knopp 《Journal of Solid State Electrochemistry》2000,4(8):425-434
Polycrystalline chemical vapor deposition (CVD) diamonds films grown on silicon substrates using the microwave-enhanced CVD
technique were polished using the thermochemical polishing method. The surface morphology of the samples was determined by
optical and scanning electron microscopes before and after polishing. The average surface roughness of the as-grown films
determined by the stylus profilometer yielded 25 μm on the growth side and about 7 μm on the substrate side. These figures
were almost uniform for all the samples investigated. Atom force microscopic measurements performed on the surface to determine
the average surface roughness showed that thermochemical polishing at temperatures between 700 °C and 900 °C reduced the roughness
to about 2.2 nm on both the substrate and growth sides of the films. Measurements done at intermittent stages of polishing
using confocal micro-Raman spectroscopy showed that thermochemical polishing is accompanied by the establishment of non-diamond
carbon phases at 1353 cm−1 and 1453 cm−1 at the initial stage of polishing and 1580 cm−1 at the intermediate stage of polishing. The non-diamond phases vanish after final fine polishing at moderate temperatures
and pressures. Photoluminescence of defect centers determined by an Ar+ laser (λlexct= 514.532 nm) showed that nitrogen-related centers with two zero-phonon lines at 2.156 eV and 1.945 eV and a silicon-related
center with a zero-phonon line at 1.681 eV are the only detectable defects in the samples.
Received: 26 July 1999 / Accepted: 15 November 1999 相似文献
13.
Rainer Cremer Mirjam Witthaut Dieter Neuschütz Cyril Trappe Martin Laurenzis Olaf Winkler Heinrich Kurz 《Mikrochimica acta》2000,133(1-4):299-302
Cu3N films for optical data storage were deposited on Si(100) wafers and 0.6 mm thick polycarbonate DVD base material discs at
a temperature of 50 °C by reactive magnetron sputtering. A copper target was sputtered in rf mode in a nitrogen plasma. For
basic investigations concerning the composition and structure of Cu3N, Si wafers were used as substrate material. To study the suitability of Cu3N as an optical data storage medium under technical conditions, Cu3N/Al bilayers were deposited on polycarbonate discs. The composition and structure of the films were investigated by X-ray
photoelectron spectroscopy (XPS) and X-ray diffraction (XRD).
The decomposition of Cu3N into metallic copper and nitrogen was induced and characterized with a dynamic tester consisting of an optical microscope
with an integrated high power laser diode. The change in reflectivity induced by the laser pulses was measured by a high sensitivity
photo detector. Optimized Cu3N films could be decomposed into metallic copper at pulse lengths of 200 ns. The reflectivity change from 3.2% to 33.2% for
completely transformed areas and to 12% for single bits as well as the maximum write data rate of 3.3 Mbit/s demonstrated
the suitability of Cu3N for write once optical data storage. Especially the carrier to noise ratio of 41 dB shows an increase of a factor of 3 for
this novel material as compared to conventional optical data storage media. 相似文献
14.
P. Bermejo-Barrera Antonio Moreda-Piñeiro Jorge Moreda-Piñeiro Adela Bermejo-Barrera 《Analytical and bioanalytical chemistry》1997,358(7-8):844-847
Rapid methods were developed for the direct determination of Ag, Al, Cd and Mn in cocaine and heroin by ETAAS using programmes
omitting the charring step . Sample pretreatment was simple: dissolution in ultrapure water or in 35.0% (v/v) HNO3 for heroin or cocaine, respectively. Optimum drying temperatures were 250 °C for Ag, Al and Mn, and 300 °C for Cd. The run
cycles were 35 and 37 s, for Ag and Al respectively, and 36 s for Cd and Mn. The best results were obtained with Pd, Mg(NO3)2 and (NH4)2HPO4, as chemical modifiers. The limits of detection were 8.6, 55.9, 2.2 and 12.4 μg kg-1 for Ag, Al, Cd and Mn, respectively.
Received: 14 November 1996/Revised: 14 January 1997/Accepted: 18 January 1997 相似文献
15.
Boris Orel Marjeta Maček Jože Grdadolnik Anton Meden 《Journal of Solid State Electrochemistry》1998,2(4):221-236
Niobium oxide (Nb2O5) films and powders have been obtained via the sol-gel route from an NbCl5 precursor. XRD spectra revealed that films with pseudohexagonal (TT-phase) and orthorhombic (T-phase) structure were formed
at 500 °C and 800 °C, respectively, while at 300 °C films were amorphous. Infrared (IR) and Raman spectra of powders and
films of Nb2O5 in different polymorphic forms were detected, and vibrational band assignments were made. Electrochromic properties of amorphous
films and films with the TT-phase were established from in situ ultraviolet visible (UV-Vis) spectroelectrochemical measurements
and correlated with ex situ IR transmission spectra of charged films. Ex situ IR spectra revealed that charging of amorphous
films is accompanied by variations of the Nb-O stretching mode intensity, while, for films with the TT- and T-phase, splitting
of the Nb3-O stretching modes and the appearance of polaron absorption were noted with Li+ ion insertion. Ex situ X-ray diffraction (XRD) spectra of charged films with the TT-phase showed changes of the unit cell
dimensions with charging. The influence of the polaron absorption on the ex situ near-grazing incidence angle (NGIA) IR reflection-absorption
spectra of charged/discharged films is discussed in detail.
Received: 21 August 1997 / Accepted: 9 October 1997 相似文献
16.
Yang Ren Gaoyang Zhao Chenxi Zhang Yuanqing Chen 《Journal of Sol-Gel Science and Technology》2012,61(3):565-569
CuAlO2 thin films were deposited on quartz substrates by sol–gel process using copper acetate monohydrate and aluminum nitrate nanohydrate
as starting materials and isopropyl alcohol as solvent. The influence of annealing temperature on the film structure and the
phase evolution of CuAlO2 films were investigated, so as to obtain CuAlO2 films with superior performance. The phase compositions of the films were dependent on the annealing temperature. The films
annealed at temperatures below 400 °C were amorphous while those annealed above 400 °C were polycrystalline. The phases of
CuO and CuAl2O4 appeared gradually with the increase of annealing temperature. When the heat treatment temperature was elevated to 900 °C,
the uniform and dense films with single phase of CuAlO2 were obtained, with a resistivity of 15 Ωcm. The transmittance of the 310 nm-thick CuAlO2 film is 79% at 780 nm and the direct optical band gap is 3.43 eV. 相似文献
17.
Volha A. Matylitskaya Wolfgang Bock Klaus Thoma Bernd O. Kolbesen 《Mikrochimica acta》2006,156(1-2):33-37
The oxidation and nitridation processes of niobium films in a rapid thermal processing (RTP) – system were investigated. 200
and 500 nm niobium films were deposited via sputtering on sapphire-(1-102)-substrate. At first niobium films were oxidized
in molecular oxygen at temperatures ranging from 350 to 500 °C and for times of 1, 2 and 5 min and then nitridated in ammonia
at 1000 °C for 1 min using an RTP system. For characterisation of the niobium films complementary analytical methods were
used: X-ray diffraction (XRD) for phase analysis, secondary ion mass spectrometry (SIMS) for determining the elemental depth
profiles of the films, scanning electron microscopy (SEM) and atomic force microscopy (AFM) for characterisation of the surface
morphology of the films. The influence of the substrate, single crystalline sapphire, on the reactivity of the niobium films
was studied in dependence of temperature, time of reaction and film thickness. The possibility of existence of niobium oxynitride
phase was investigated. According to XRD and SIMS data, there is evidence that an oxynitride phase is formed after oxidation
and subsequent nitridation in the bulk of some Nb films. In some of the experiments crack formation in the films or even delamination
of the Nb films from the substrates was observed. 相似文献
18.
Uniform particles of manganese compounds obtained by forced hydrolysis of manganese(II) acetate 总被引:1,自引:0,他引:1
M. Ocaña 《Colloid and polymer science》2000,278(5):443-449
Procedures for the preparation at low temperature (80 °C) of uniform colloids consisting of Mn3O4 nanoparticles (about 20 nm) or elongated α-MnOOH particles with length less than 2 μm and width 0.4 μm or less, based on
the forced hydrolysis of aqueous manganese(II) acetate solutions in the absence (Mn3O4) or the presence (α-MnOOH) of HCl are described. These solids are only produced under a very restrictive range of reagent
concentrations involving solutions of 0.2–0.4 mol dm−3 manganese(II) acetate for Mn3O4 and of 1.6–2 mol dm−3 Mn(II) and 0.2–0.3 mol dm−3 HCl for α-MnOOH. The role that the acetate anions play in the precipitation of these solids is analyzed. It seems that these
anions promote the oxidation of Mn(II) to Mn(III), which readily hydrolyze causing precipitation. The evolution of the characteristics
of the powders with temperature up to 900 °C is also reported. Thus, Mn3O4 particles transform to Mn2O3 upon calcination at 800 °C; this is accompained by a sintering process. The α-MnOOH sample also experiences several phase
transformations on heating. First, it is oxidized at low temperatures (250–450 °C) giving MnO2 (pyrolusite), which is further reduced to Mn2O3 at 800 °C. After this process the particles still retain their elongated shape.
Received: 19 October 1999 Accepted: 24 November 1999 相似文献
19.
Xiu-Bin Ren Hai-Yan Lu Hai-Bo Lin Ya-Nan Liu Yan Xing 《Russian Journal of Electrochemistry》2010,46(1):77-80
WO3 films have been prepared onto IrO2-coated Ti substrate by electro-deposition, and as-deposited and annealed films have been characterized by using Raman spectroscopy.
It was found that the asdeposited film consists of orthorhombic WO3 · H2O phase, which transforms to amorphous WO3 by annealing at 250°C and to monoclinic phase by annealing at and above 350°C. All electrochemical experiments were carried
on Ti/IrO2/WO3 annealed at 450°C. The open-circuit potential could change significantly due to the hydration of the coating film. However
this process is fairly slow. Reproducible voltammograms could be obtained quickly, further revealing high electrochemical
stability of the Ti/IrO2/WO3 electrode. And the shapes of CV show the approximate rectangular mirror image, showing the typical characteristic of capacitive
behavior. The specific capacitance obtained at a scan rate of 50 mV s−1 is 46 F g−1. 相似文献
20.
Graham A. Bowmaker Paul A. Kilmartin Graham A. Wright 《Journal of Solid State Electrochemistry》1999,3(3):163-171
Stable, yellow anodic films of parathiocyanogen (SCN)
x
were formed on a platinum electrode from 2.8 M KSCN in methanol at 45 °C at a constant current of 20–40 mA cm−2 for 15–30 min. Loosely bound orange crystals of a more amorphous character were removed by rinsing to leave an adherent yellow
film with sharp Raman bands under 647.1 nm laser excitation at 627 cm−1 (vCS), 1152 cm−1 and 1236–1261 cm−1 (vNN and vCN). The lack of electroactivity and short-lived photocurrents pointed to an insulating film at potentials up to 1.0 V (SHE).
At more positive potentials, longer-lasting photocurrents were obtained, consistent with breakdown of the insulating film.
XPS scans confirmed N:C:S ratios close to 1:1:1, with a deficiency of S of some 10% due to S lost as sulfate at the film surface.
Oxidation of SeCN− in neutral aqueous solution led to the formation of a less-stable orange paraselenocyanogen film with a Raman band at 1256–1267 cm−1, which decomposed within a day to grey selenium.
Received: 12 December 1997 / Accepted: 23 March 1998 相似文献