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1.
Highly conducting and transparent thin films of tungsten (W)-doped indium oxide were obtained using pulsed laser deposition to study the effect of growth temperature and oxygen pressure on structural, optical and electrical properties. The transparency of the films is seen to largely depend on the growth temperature. The electrical properties, however, are found to depend strongly on both the growth temperature and the oxygen pressure. High mobility (up to 358 cm2 V−1 s−1), low resistivity (1.1 × 10−4 Ω cm), and relatively high transmittance (∼90%) tungsten-doped indium oxide films have been prepared at a growth temperature of 500 °C and an oxygen pressure of 1 × 10−6 bar.  相似文献   

2.
Simultaneous dilatometric and electrochemical measurements are employed for studying the kinetic parameters and mechanism for hydrogen transport through metal oxides. As a model, CeO2 layer on a palladium wire substrate is investigated. Hydrogen is dissolved in aqueous solutions where their acidity and the oxide layer thickness are the studied parameters. Based on both open circuit potential and length changes, it is deduced that molecular diffusion through pores and imperfections in the ceria lattice is the rate determining step and no chemical reactions are involved in the oxide bulk. The following diffusion coefficients are calculated by using a diffusional transport model: D(1 N KOH)=1.69×10−11 cm2 s−1D(1 N H2SO4)=1.72×10−11 cm2 s−1.  相似文献   

3.
By ablating titanium containing In2O3 target with a KrF excimer laser, highly conducting and transparent films on quartz were obtained to investigate the effects of growth temperature and oxygen pressure on the structural, optical and electrical properties of these films. We find that the transparency of the films depends more on the growth temperature and less on the oxygen pressure. Electrical properties, however, are found to be sensitive to both the growth temperature and oxygen pressure. We report in this paper that a growth temperature of 500 °C and an oxygen pressure of 7.5 × 10−7 bar lead to titanium-doped indium oxide films which have high mobility (up to 199 cm2 V−1 s−1), low resistivity (9.8 × 10−5 Ω cm), and relatively high transmittance (∼88%).  相似文献   

4.
A series of Ce1−xCuxO2 nanocomposite catalysts with various copper contents were synthesized by a simple hydrothermal method at low temperature without any surfactants, using mixed solutions of Cu(II) and Ce(III) nitrates as metal sources. These bimetal oxide nanocomposites were characterized by means of XRD, TEM, HRTEM, EDS, N2 adsorption, H2-TPR and XPS. The influence of Cu loading (5-25 mol%) and calcination temperature on the surface area, particle size and catalytic behavior of the nanocomposites have been discussed. The catalytic activity of Ce1−xCuxO2 nanocomposites was investigated using the test of CO oxidation reaction. The optimized performance was achieved for the Ce0.80Cu0.20O2 nanocomposite catalyst, which exhibited superior reaction rate of 11.2 × 10−4 mmol g−1 s−1 and high turnover frequency of 7.53 × 10−2 s−1 (1% CO balanced with air at a rate of 40 mL min−1, at 90 °C). No obvious deactivation was observed after six times of catalytic reactions for Ce0.80Cu0.20O2 nanocomposite catalyst.  相似文献   

5.
The electrical transport coefficients of anti-ferromagnetic CaMnO3 have been investigated by density functional theory calculation within generalized gradient approximation. The calculated transport coefficients exhibit the anisotropic nature, in agreement with its electronic states. The transport property results reveal the stronger carrier transport along the O1–Mn–O1 plane within the O–Mn–O octahedron, indicating that the Mnd and O1p orbitals are mainly responsible for electrical transport. The maximum power factor values as a function of relaxation time reach 8.4×1023 Wm−1 K−2 s−1, 7.9×1023Wm−1 K−2 s−1 and 4.9×1023 Wm−1 K−2 s−1 within c, a and b direction, respectively. The dimensionless figure of merit ZTxx, ZTyy as well as ZTzz is estimated with 1.28, 0.8 and 1.37 at 1000 K, respectively.  相似文献   

6.
d-limonene in water nanoemulsion was prepared by ultrasonic emulsification using mixed surfactants of sorbitane trioleate and polyoxyethylene (20) oleyl ether. Investigation using response surface methodology revealed that 10% d-limonene nanoemulsions formed at S0 ratio (d-limonene concentration to mixed surfactant concentration) 0.6-0.7 and applied power 18 W for 120 s had droplet size below 100 nm. The zeta potential of the nanoemulsion was approximately −20 mV at original pH 6.4, closed to zero around pH 4.0, and around −30 mV at pH 12.0. The main destabilization mechanism of the systems is Ostwald ripening. The ripening rate at 25 °C (0.39 m3 s−1 × 1029) was lower than that at 4 °C (1.44 m3 s−1 × 1029), which was in agreement with the Lifshitz-Slezov-Wagner (LSW) theory. Despite of Ostwald ripening, the droplet size of d-limonene nanoemulsion remained stable after 8 weeks of storage.  相似文献   

7.
The nature of the conformational transition of the polymers with Ru (II) polypyridyl complexes covalently attached to poly(acrylic acid) (PAA) and poly(metacrylic acid) (PMAA) has been in studied in aqueous solutions at different pH values. The [PAA-Ru4]8+ and [PMAA-Ru4]8+ polymers has been investigated by means of the luminescence properties of the Ru(bpy)32+ moiety by steady-state and time-resolved luminescence spectroscopy. The pH markedly affects the luminescence spectra and quantum yields of both ruthenium-polyacid complexes in aqueous solution. Another feature investigated in this work was a comparative study of their luminescence quenching by acridinic dyes in solution. The analysis of the kq values obtained indicates that the bimolecular quenching by acridinium and 9-aminoacridinium is more effective in the [PAA-Ru4]8+ complex (6.4×109 and 1.4×109 M−1 s−1, respectively) compared to the [PMAA-Ru4]8+ (2.6×109 and 1.0×109 M−1 s−1). Also, a similar behavior was evidenced for the Ru solely adsorbed onto pure PAA (9.0×109 and 3.4×109 M−1 s−1) and PMAA (1.8×109 and 1.7×109 M−1 s−1) in aqueous solution. The effect of enhancement of quenching rate constant in [PAA-Ru4]8+ system could be ascribed to the higher density of Ru per polymer chain. The average number per chain is similar in both systems, but the molecular weight is lower for [PAA-Ru4]8+. Furthermore, the larger hydrophilic environment provided by the PAA exposes the Ru probe to the outer surface of the polymer in solution.  相似文献   

8.
Transparent and conducting zirconium-doped zinc oxide films with high transparency and relatively low resistivity have been successfully prepared by RF magnetron sputtering at room temperature. The deposition pressure was varied from 0.6 to 2.5 Pa. A transformation from a relatively compact structure to individual grains was observed with the increase of deposition pressure. As the deposition pressure increases, the resistivity increases sharply due to both, the decrease of hall mobility and carrier concentration. The lowest resistivity achieved was 2.07 × 10−3 Ω cm at a deposition pressure of 0.6 Pa with a hall mobility of 16 cm2 V−1 s−1 and a carrier concentration of 1.95 × 1020 cm−3. The films are polycrystalline with a hexagonal structure and a preferred orientation along the c-axis. All the films present a high transmittance of above 90% in the visible range. The optical band gap decreases from 3.35 to 3.20 eV as the deposition pressure increases from 0.6 to 2.5 Pa.  相似文献   

9.
Atomic H and Cl were monitored by time-resolved resonance spectroscopy in the vacuum ultraviolet, following 193 nm laser flash photolysis of C6H5Cl and mixtures with NH3, over 300-1020 K and with Ar bath gas pressures from 30 to 440 mbar. Below 550 K simple exponential decays of [H] were observed, and attributed to addition to form chlorocyclohexadienyl radicals. This addition was reversible over 550-630 K and the equilibrium constant was determined by a third law approach. The addition rate constant can be summarized as (1.51 ± 0.11) × 10−11exp((−1397 ± 29)/T) cm3 molecule−1 s−1 (300-630 K, 1σ uncertainties), and the C-H bond dissociation enthalpy in 1-chlorocyclohexadienyl was determined to be 108.1 ± 3.3 kJ mol−1 at 298 K. At higher temperatures the photolysis of chlorobenzene yielded H atoms, which is attributed to the reaction of phenyl with chlorobenzene with a rate constant of (4.5 ± 1.8) × 10−10exp((−4694 ± 355)/T) cm3  molecule−1 s−1 over 810-1020 K. These and other reaction pathways are discussed in terms of information about the potential energy surface obtained via B3LYP/6-311G(2d,d,p) density functional theory.  相似文献   

10.
Ab initio transition state theory (TST) based master equation simulations are used to predict the temperature and pressure dependence of the H + NCO reaction rate and product branching. The barrierless entrance channels to form singlet HNCO and NCOH are studied with variable reaction coordinate TST employing a potential energy surface obtained from multi-reference configuration interaction ab initio calculations. The remaining channels, including reactions on the triplet surface, are studied with standard TST methods employing high level electronic structure results. The energy transfer parameters for the master equation simulations arise from a fit to the experimentally observed HNCO dissociation rate. The lowest energy threshold to formation of bimolecular products, 3NH + CO, lies well below the reactants. The bottleneck for intersystem crossing, which precedes the formation of 3NH + CO from the singlet adducts, becomes the dominant bottleneck for that channel at quite low energies relative to reactants. The effect of this bottleneck is studied with model calculations designed to reproduce detailed experimental observations of photolysis branching ratios. This bottleneck greatly reduces the flux from H + NCO to 3NH + CO via the singlet adducts. As a result, stabilization and reaction on solely the triplet surface are significant components of the overall rate. The present predictions for the high pressure and collisionless limit rate coefficients are accurately reproduced over the 200-2500 K range by the expressions, 1.53 × 10−5T−1.86exp(−399/T) + 1.07 × 103T−3.15exp(−15219/T) and 5.62 × 10−12T0.493exp(148/T) cm3 molecule−1 s−1, respectively, where T is in K. These predictions are in reasonably satisfactory agreement with the somewhat discordant experimental rate measurements.  相似文献   

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