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1.
Bending strength and the effective modulus of atmospheric ice accumulated in a closed loop wind tunnel at temperatures − 6 °C, − 10 °C and − 20 °C with a liquid water content of 2.5 g/m3 have been studied at different strain rates. More than 120 tests have been conducted. Ice samples, accumulated at each temperature, have been tested at the accumulation temperature. In addition, tests have been performed at temperatures of − 3 °C and − 20 °C, for the ice accumulated at − 10 °C. These tests showed a clear dependency of bending strength of atmospheric ice on test temperature at low strain rates. Strain rate effects are implied because the spread in bending strength for the different temperatures diminishes as strain rate increases. The results also reveal that, in most cases, the effective modulus of atmospheric ice increases with increasing strain rate. The bending strength of atmospheric ice accumulated at − 10 °C has been found to be greater than that of ice accumulated at − 6 °C and − 20 °C. The results show that the effective modulus of ice accumulated at − 20 °C at higher strain rates is less than that of the two other types.  相似文献   

2.
Uniform Al2O3 films were deposited on silicon substrates by the sol–gel process from stable coating solutions. The technological procedure includes spin coating deposition and investigating the influence of the annealing temperature on the dielectric properties. The layers were studied by Fourier transform infrared spectroscopy and Scanning Electron Spectroscopy. The electrical measurements have been carried out on metal–insulator–semiconductor (MIS) structures. The C–V curves show a negative fixed charge at the interface and density of the interface state, Dit, 3.7 × 1011 eV− 1cm− 2 for annealing temperature at 750 °C.  相似文献   

3.
The construction of amperometric xanthine biosensor by immobilization of xanthine oxidase (XOD) on the multi-wall carbon nanotubes (CNTs) modified glassy carbon (GC) electrode surface was investigated. The direct chemistry of XOD was accomplished and the formal potential was about − 0.465 V (vs SCE). The heterogeneous electron transfer rate constant was evaluated to be 2.0 ± 0.3 s− 1. The xanthine biosensor based on XOD entrapped in silica sol–gel (SG) thin film on CNTs-modified GC electrode surface was also investigated. The XOD still maintains its activity to xanthine. The amperometric response to xanthine showed a linear relation in the range from 0.2 µM to 10 µM and a detection limit of 0.1 µM (S/N = 3). The enzyme electrode retained 95% of its initial activity after 90 days of storage. The sensor exhibited high sensitivity, rapid response and good long-term stability.  相似文献   

4.
In this paper, glucose biosensor is fabricated with immobilization of glucose oxidase (GOx) in platinum and silica sol. The glucose biosensor combined with Pt and SiO2 nanoparticles could make full use of the properties of nanoparticles. A set of experimental results indicates that the current response for the enzyme electrode containing platinum and silica nanoparticles increases from 0.32 µA cm− 2 to 33 µA cm− 2 in the solution of 10 mM β-D-glucose. The linear range is 3 × 10− 5 to 3.8 × 10− 3 M with a detection limit of 2 × 10− 5 M at 3σ. The effects of the various volume ratios of Pt and SiO2 sols with respect to the current response and the stability of the enzyme electrodes are studied.  相似文献   

5.
LiOH·H2O, Co(NO3)2·6H2O and NH4VO3 were used to prepare nano-crystalline LiCoVO4 by 150 °C solvothermal reaction in isopropanol for 10–360 h and subsequent calcination at 300–500 °C for 6 h. XRD, TEM and selected area electron diffraction (SAED) revealed the presence of nano-crystalline LiCoVO4 with inverse spinel structure. The V–O stretching vibration modes of VO4 tetrahedrons were detected by FTIR over the range 617–835 cm− 1 and by Raman spectrometer at 805.7 and 783.1 cm− 1. Co, V and O were detected by EDX. TGA of solvothermal products shows weight loss due to the evaporation and decomposition processes at 40–648 °C.  相似文献   

6.
P.H. Tai  C.H. Jung  Y.K. Kang  D.H. Yoon   《Thin solid films》2009,517(23):129-6297
12CaO·7Al2O3 electride (C12A7:e) doped indium tin oxide (ITO) (ITO:C12A7:e) thin films were fabricated on a glass substrate by an RF magnetron co-sputtering system with increasing number of C12A7:e chips (from 1 to 7) and at various oxygen partial pressure ratios. The optical transmittance of the ITO:C12A7:e thin film was higher than 70% in the visible wavelength region. In the electrical properties of the thin film, a decrease of the carrier concentration from 2.6 × 1020 cm− 3 to 2.1 × 1018 cm− 3 and increase of the resistivity from 1.4 × 10− 3 Ω cm to 4.1 × 10− 1 Ω cm were observed with increasing number of C12A7:e chips and oxygen partial pressure ratios. It was also observed that the Hall mobility was decreased from 17.27 cm2·V− 1·s− 1 to 5.13 cm2·V− 1·s− 1. The work function of the ITO thin film was reduced by doping it with C12A7:e.  相似文献   

7.
Tungsten trioxide (WO3) electrochromic coatings have been formed on indium tin oxide-coated glass substrates by aqueous routes. Coating sols are obtained by dissolving tungsten powder in acetylated (APTA) or plain peroxotungstic acid (PTA) solutions. The structural evolution and electrochromic performance of the coatings as a function of calcination temperature (250 °C and 400 °C) have been reported. Differential scanning calorimetry and X-ray diffraction have shown that amorphous WO3 films are formed after calcination at 250 °C for both processing routes; however, the coatings that calcined at 400 °C were crystalline in both cases. The calcination temperature-dependent crystallinity of the coatings results in differences in optical properties of the coatings. Higher coloration efficiencies can be achieved with amorphous coatings than could be seen in the crystalline coatings. The transmittance values (at 800 nm) in the colored state are 35% and 56% for 250 °C and 400 °C-calcined coatings, respectively. The electrochemical properties are more significantly influenced by the method of sol preparation. The ion storage capacities designating the electrochemical properties are found in the range of 1.62–2.74 × 10− 3 (mC cm− 2) for APTA coatings; and 0.35–1.62 × 10− 3 (mC cm− 2) for PTA coatings. As a result, a correlation between the microstructure and the electrochromic performance has been established.  相似文献   

8.
In this work, undoped amorphous silicon layers were deposited on n-type AIC seed films and then annealed at different temperatures for epitaxial growth. The epitaxy was carried out using halogen lamps (rapid thermal process or RTP) or a tube conventional furnace (CTP). We investigated the morphology of the resulting 2 µm thick epi-layers by means of optical microscopy. An average grain size of about 40 µm is formed after 90 s annealing at 1000 °C in RTP. The stress and degree of crystallinity of the epi-layers were studied by micro-Raman Spectroscopy and UV–visible spectrometer as a function of annealing time. The presence of compressive stress is observed from the peak position which shifts from 520.0 cm− 1 to 521.0 cm− 1 and 522.3 cm− 1 after CTP annealing for 10 min and 90 min, respectively. It is shown that the full width at half maximum (FWHM) varies from 9.8 cm− 1 to 15.6 cm− 1, and the magnitude of stress is changing from 325 MPa to 650 MPa. Finally, the highest crystallinity is achieved after annealing at 1000 °C for 90 min in a tube furnace exhibiting a crystalline fraction of 81.5%. X-ray diffraction technique was used to determine the preferential orientation of the poly-Si thin films formed by SPE technique on n+ type AIC layer. The preferential orientation is 100 for all annealing times at 1000 °C.  相似文献   

9.
A plasticized poly (vinyl chloride) membrane electrode based on 1,3-bis(2-methoxybenzene)triazene (MBT) for highly selective determination of mercury(II) has been developed. The electrode showed a good Nernstian response (30.2 ± 0.3 mV decade− 1) over a wide concentration range (1.0 × 10− 7−1.0 × 10− 2 mol L− 1). The limit of detection was 5.0 × 10− 8 mol L− 1. The electrode has a response time about 15 s and can be used for at least 1 month without observing any deviation from Nernstain response. The proposed electrode revealed an excellent selectivity toward mercury(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions and could be used in the pH range 2.6–4.2. The electrode was used in the determination of Hg2+ in aqueous samples and as an indicator electrode in potentiometric titration of Hg(II) ions.  相似文献   

10.
Quaternary Si–B–C–N materials are becoming increasingly attractive due to their possible high-temperature and harsh-environment applications. In this work, amorphous Si–B–C–N films with two compositions (Si34B9C4N49 and Si36B13C7N40) and low contamination level (H + O + Ar < 4 at.%) were deposited on silicon substrates by reactive dc magnetron co-sputtering using two different targets and gas mixtures. Thermal stability of these films was investigated in terms of composition, bonding structure, as well as mechanical and optical properties after annealing in helium up to a 1300°C substrate limit. Films with a high nitrogen content (Si34B9C4N49, i.e. N/[Si + B + C]~ 1.0) were found to be stable up to 1300°C. After annealing, the hardness and elastic recovery of those films slightly increased up to 27 GPa and 84%, respectively, and the reduced Young's modulus remained practically constant (~ 170 GPa). The refractive index and the extinction coefficient at 550 nm were evaluated at 2.0 and 5 × 10− 4, respectively, and the optical band gap was approximately 3.0 eV. In contrast, films with a lower nitrogen content (Si36B13C7N40, i.e. N/[Si + B + C]~ 0.7) were stable only up to 1200°C. Both Si–B–C–N materials studied here exhibited extremely high oxidation resistance in air up to the 1300°C substrate limit.  相似文献   

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