共查询到20条相似文献,搜索用时 31 毫秒
1.
Harvey J. Flitt 《Corrosion Science》2010,52(6):1905-580
SYMADEC 1, used previously to synthesise, match and deconstruct polarization curves for the Fe/H2O/H+/O2(4e−) corrosion system, has been updated to SYMADEC Multimetal. The polarization curve of a zinc anode alloy corroding with formation of a non-protective layer of ZnO in fully-aerated, near-neutral NaCl solution was modelled. To test the SYMADEC Multimetal model four published polarization curves of zinc actively corroding in similar salt solutions are deconstructed. The polarization curve current/voltage contribution from the ZnO reduction/oxidation peak overlaid on the polarization curve is estimated by a bi-Gaussian relationship. 相似文献
2.
Longyan Yuan Guojia Fang Chun Li Mingjun Wang Xingzhong Zhao 《Surface & coatings technology》2008,202(15):3480-3484
Vertically well-aligned single crystal ZnO nanorod arrays were synthesized and enhanced field electron emission was achieved with hafnium nitride (HfNx) coating under proper sputtering condition. HfNx films with various composition have been coated on ZnO nanorod arrays using a reactive direct current (DC) magnetron sputtering system. Morphology and crystal configuration of the ZnO nanorod arrays were investigated by scanning electron microscopy and X-ray diffraction. The field emission properties of the coated and uncoated ZnO nanorod arrays were characterized. The as-grown ZnO nanorod arrays showed a turn-on electric field of 6.60 V μm− 1 at a current density of 10 μA cm− 2 and an emission current density of 1 mA cm− 2 under the field of 9.32 V μm− 1. While the turn-on electric field of the coated ZnO nanorod arrays sharply decreased to 2.42 V μm− 1, an emission current density of 1 mA cm− 2 under the field of only 4.30 V μm− 1 can be obtained. A method to accurately measure the work function of the coated films was demonstrated. 相似文献
3.
Linhua Xu Fang GuJing Su Yulin ChenXiangyin Li Xiaoxiong Wang 《Journal of Alloys and Compounds》2011,509(6):2942-2947
In this work, 1 at.% K-doped ZnO thin films were prepared by sol-gel method on Si substrates. The evolution behavior of the structures and photoluminescence of these films under different annealing temperatures was deeply studied. The crystal structures and surface morphology of the samples were analyzed by an X-ray diffractometer and an atomic force microscope, respectively. The photoluminescence spectra were used to study the luminescent behavior of the samples. The results showed that the films had a hexagonal wurtzite structure and were preferentially oriented along the c-axis perpendicular to the substrate surface. All the samples showed a strong ultraviolet emission and a weak blue emission. With the increase of annealing temperature, the ZnO grains gradually grew up; at the same time, the blue emission gradually decreased. The sample annealed at 500 °C showed the best crystalline quality and strongest ultraviolet emission. The authors think that the blue emission in these samples is mainly connected with K interstitial defects. When the 1 at.% K-doped ZnO thin film is annealed at high temperatures (≥600 °C), most of K interstitials move into ZnO lattice sites replacing Zn. As a result, the blue emission resulting from K interstitial defects also decreased. 相似文献
4.
N.H. ErdoganK. Kara H. OzdamarH. Kavak R. EsenH. Karaagac 《Journal of Alloys and Compounds》2011,509(36):8922-8926
In this study, N-doped ZnO thin films were fabricated by oxidation of ZnxNy films. The ZnxNy thin films were deposited on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) using metallic zinc wire (99.999%) as a cathode target in pure nitrogen plasma. The influence of oxidation temperature, on the electrical, structural and optical properties of N-doped ZnO films was investigated. P-type conduction was achieved for the N-doped ZnO obtained at 450 °C by oxidation of ZnxNy, with a resistivity of 16.1 Ω cm, hole concentration of 2.03 × 1016 cm−3 and Hall mobility of 19 cm2/V s. X-ray photoelectron spectroscopy (XPS) analysis confirmed the incorporation of N into the ZnO films. X-ray diffraction (XRD) pattern showed that the films as-deposited and oxidized at 350 °C were amorphous. However, the oxidized films in air atmosphere at 450-550 °C were polycrystalline without preferential orientation. In room temperature photoluminescence (PL) spectra, an ultraviolet (UV) peak was seen for all the samples. In addition, a broad deep level emission was observed. 相似文献
5.
T. Prasada Rao M.C. Santhosh Kumar 《Journal of Alloys and Compounds》2011,509(35):8676-8682
Lithium and nitrogen dual acceptors-doped p-type ZnO thin films have been prepared using spray pyrolysis technique. The influence of dual acceptor (Li, N) doping on the structural, electrical, and optical properties of (Li, N):ZnO films are investigated in detail. The (Li, N):ZnO films exhibit good crystallinity with a preferred c-axis orientation. From AFM studies, it is found that the surface roughness of the thin films increases with the increase of doping percentage. The Hall Effect measurements showed p-type conductivity. The Hall measurements have been performed periodically up to seven months and it is observed that the films show p-type conductivity throughout the period of observation. The samples with Li:N ratio of 8:8 mol% showed the lowest resistivity of 35.78 Ω cm, while sample with Li:N ratio of 6:6 mol% showed highest carrier concentration. The PL spectra of (Li, N):ZnO films show a strong UV emission at room temperature. Furthermore, PL spectra show low intensity in deep level transition, indicating a low density of native defects. This indicates that the formation of intrinsic defects is effectively suppressed by dual acceptor (Li, N) doping in ZnO thin films. The chemical bonding states of N and Li in the films were examined by XPS analysis. 相似文献
6.
NaCl induced atmospheric corrosion of ZnAl2Mg2 coated, electrogalvanised (EG) and hot dipped galvanised (HDG) steel was studied using in situ infrared reflection absorption spectroscopy, XRD and SEM. Initial corrosion leads to the formation of Mg/Al and Zn/Al layered double hydroxides (LDHs) on ZnAl2Mg2, due to the anodic dissolution of Zn–MgZn2 phases and cathodic oxygen reduction on Zn–Al–MgZn2, Al-phases and on zinc dendrites. In contrast to EG and HDG, were no ZnO and Zn5(OH)8Cl2⋅H2O detected. This is explained by the buffering effect of Mg and Al which inhibit the ZnO formation, reduce the cathodic reaction and corrosion rate on ZnAl2Mg2. 相似文献
7.
In this paper, composite fluorocarbon/ZnO films were prepared by R.F. sputtering used polytetrafluoroethylene (PTFE) and Zn target on polyethylene terephthalate (PET) substrate. Argon was used as the working gas and oxygen used as reacting gas. The obtained films were characterized by means of SEM, XPS and UV-visible spectrophotometer. It was found, the surface morphology of composite fluorocarbon/ZnO films vary as the deposited time of ZnO. The growing mode of composite films is the deposition and expansion. The ultraviolet absorbance of composite fluorocarbon/ZnO films is equal to that of fluorocarbon films' when deposited time of ZnO is within 2 min, while distinctively increases when deposited time of ZnO exceeds 5 min, the absorbance value is larger than the ZnOs'. The composite films exhibit multi-enhanced ultraviolet absorption due to π-conjugated molecular structure, nanoparticle-pore reflection and the absorption effect of nanosized ZnO particles. 相似文献
8.
M.K. SharmaR.N. Gayen A.K. Pal D. KanjilalRatnamala Chatterjee 《Journal of Alloys and Compounds》2011,509(26):7259-7266
Mn-doped (2.6-4.8 at%) aligned zinc oxide (Mn:ZnO) nanorod-films were synthesized by hybrid wet chemical route onto glass substrates. The chemical composition, structural, microstructural and magnetic studies were performed to investigate the origin of observed room temperature ferromagnetism (∼0.11 μB/Mn) in these Mn doped ZnO nanorod-films. XPS studies indicated that incorporated Mn was in Mn2+ and Mn4+ states. Mn2+ atomic concentration was found to be significantly larger than Mn4+ concentration in all the samples. Disappearance of the Raman peak at ∼577 cm−1 arising due to the Zn interstitials may be related to the substitution of Mn2+ in the Zn2+ site with annealing. Thus, Mn metal inclusions as Mn2+ in the ZnO lattice are possibly responsible for such large magnetic moment in the films. 相似文献
9.
10.
The room-temperature oxygen plasma treatment before depositing ZnO films on nanocrystalline diamond substrates was studied. The nanocrystalline diamond substrates were pretreated in oxygen plasma at 50 W for 30 min at room temperature and then ZnO films were sputtered on diamond substrates at 400 W. The X-ray diffraction (XRD) patterns show that the c-axis orientation of ZnO film increases evidently after oxygen plasma pretreatment. The AFM and SEM measurements also show that the high c-axis orientation of ZnO film and the average surface roughness is less than 5 nm. The resistivity of ZnO films increases nearly two orders of magnitude to 1.04 - 10^8 Ω.cm. As a result, room-temperature oxygen plasma pretreatment is indeed a simple and effective way to improve the performance of ZnO film used in SAW devices by ameliorating the combination between diamond film and ZnO film and also complementing the absence of oxygen atoms in ZnO film. 相似文献
11.
Dong-Suk KangHyo Sung Lee Seok Kyu HanVibha Srivastava Eadi Sunil BabuSoon-Ku Hong Min-Jung KimJae-Ho Song Jung-Hoon SongHyojin Kim Dojin Kim 《Journal of Alloys and Compounds》2011,509(16):5137-5141
We report on the synthesis of high-quality ZnO nanorods by combining hydrothermal growth (HG) and chemical vapor deposition (CVD) processes. Vertically aligned and closely packed ZnO nanorods were grown by HG on a sputtered ZnO seed layer on a SiO2/Si (0 0 1) substrate. The top surface of the HG-prepared ZnO nanorods showed very flat surfaces compared with that of the sputtered ZnO seed layer. Therefore, the HG-prepared ZnO nanorods were used as a new alternative seed material for the CVD growth of the ZnO nanorods. Vertical ZnO nanorods were grown by CVD on both the new HG-prepared nanorod seed material and the sputtered ZnO seed layer. The CVD-prepared ZnO nanorods on new HG-prepared nanorod seed material showed better crystalline quality and superior optical properties than the CVD-prepared ZnO nanorods on sputtered seed layer. The former showed negligible deep-level emissions at room temperature photoluminescence measurements. The intensity ratio of near-band-edge emissions to deep-level emissions from the former was about 910, but that from the latter was about 151. This implies that the HG-prepared ZnO nanorods can be used as a promising new seed material for nanostructure synthesis. 相似文献
12.
This paper discusses the effects of the coupling of ZnO–Zn, Q235 carbon steel, and 304 stainless steel on their corrosion in 3.5% NaCl under white light illumination. In the presence of Na2S, ZnO provided photoelectrochemical cathodic protection for the coupled metals. In the absence of Na2S, ZnO could only provide photoelectrochemical cathodic protection for 304 stainless steel. Under white light illumination, the open circuit potential of ZnO photoelectrode shifted in the negative direction. ZnO provided photoelectrochemical cathodic protection to the metals only when the open circuit potential of ZnO photoelectrode was more negative than that of the metals. 相似文献
13.
In order to achieve effective, economic, and easily achievable photocatalyst for the degradation of dye methyl orange (MeO), ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe2O3 nanocomposites were prepared by simple chemical synthetic route in the aqueous medium. Phase, crystallinity, surface structure and surface behavior of the synthesized materials were determined by X-ray diffraction (XRD) and Brunauer–Emmett–Teller analysis (BET) techniques. XRD study established formation of good crystalline ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe2O3 nanomaterials. By using intensity of constituent peaks in the XRD pattern, the compositions of nanocomposites were determined. From the BET analysis, the prepared materials show mesoporous behavior, type IV curves along with H4 hysteresis. The ZnO/ZnS/α-Fe2O3 composite shows the largest surface area among three materials. From the UV–visible spectra, the band gap energy of the materials was determined. Photoluminescence spectra (PL) were used to determine the emission behavior and surface defects in the materials. In PL spectra, the intensity of UV peak of ZnO/ZnS is lowered than that of ZnO while in case of ZnO/ZnS/α-Fe2O3, the intensity further decreased. The visible emission spectra of ZnO/ZnS increased compared with ZnO while in ZnO/ZnS/α-Fe2O3 it is further increased compared with ZnO/ZnS. The as-synthesized materials were used as photocatalysts for the degradation of dye MeO. The photo-degradation data revealed that the ZnO/ZnS/α-Fe2O3 is the best photocatalyst among three specimens for the degradation of dye MeO. The decrease of intensity of UV emission peak and the increase of intensity of visible emission cause the decrease of recombination of electrons and holes which are ultimately responsible for the highest photocatalytic activity of ZnO/ZnS/α-Fe2O3. 相似文献
14.
Ajay KaushalDavinder Kaur 《Journal of Alloys and Compounds》2011,509(2):200-205
We report on the structural, optical and electrical properties of ZnO/MgO multilayers grown by pulsed laser deposition technique. The film thickness of ZnO sublayer (tZnO) was found to have great impact on the properties of ZnO/MgO multilayers. Investigations reveal the structural phase transition from wurtzite phase to cubic phase with corresponding decrease in ZnO thickness. The optical transmittance of the multilayers is over 80% in the visible region and there is a gradual shift of absorption edge towards a longer wavelength with corresponding increase in ZnO sublayer thickness. Two absorption bands at around 400 nm and 270 nm were observed in the transmission spectra of ZnO/MgO multilayers for similar ZnO and MgO layer thickness, which has been ascribed to phase separation to hexagonal and cubic phases. The calculated optical band gap Eg shows a widening from 3.51 eV to 6.23 eV with corresponding decrease in ZnO sublayer thickness from 100 nm to 23 nm, which in turn leads to an increase in resistivity in ZnO/MgO multilayers. These results provide important information for the design and modeling of ZnO/MgO optoelectronic devices due to their adjustable bandgap energies. 相似文献
15.
《Synthetic Metals》2006,156(16-17):1078-1082
Polypyrrole (PPy) was prepared by chemical oxidation polymerization, analyzed by FT-IR, elemental analysis and HRTEM, and studied for gas sensitivity. It suggested that PPy had sensitivity to NH3, H2S and NOx, and showed irreversibility to NOx gas. The organic–inorganic hybrid materials PPy/ZnO with different PPy weight percents were prepared by mechanical mixing, and the sensitivity study of the materials to toxic gases NH3, H2S, NOx was carried out at different operating temperatures 30, 60, and 90 °C. It was found that PPy/ZnO materials (PPy(1%)/ZnO, PPy(3%)/ZnO, PPy(5%)/ZnO, PPy(10%)/ZnO, PPy(20%)/ZnO) had better selectivity and reversibility to NOx than pure PPy, and much lower working temperature than the reported working temperature of ZnO (about 350–450 °C). Their sensitivity increased with the increasing concentration of NOx at particular working temperature, and among them PPy(10%)/ZnO had the maximum sensitivity to NOx in the same condition. They showed no response to 1000, 1500, 2000 ppm NH3 or H2S. The response mechanism of PPy/ZnO materials to NOx was discussed. 相似文献
16.
Liang Zhou Wancheng ZhouTao Liu Fa LuoDongmei Zhu 《Journal of Alloys and Compounds》2011,509(19):5903-5907
ZnO/Al2O3 coatings were prepared by atmospheric plasma spraying (APS) using ZnO powders and Al2O3 powders as starting materials. The dielectric properties of these coatings were discussed. Both the real part of permittivity and the energy loss increase greatly with increasing ZnO content over the frequency range 8.2-12.4 GHz, which can be ascribed to orientation polarization and relaxation polarization due to a higher ZnO content. The frequency-dependent maximum of the loss tangent is found to obey Debye theory. In addition, annealing temperature which leads to the change of ZnO content also plays an important role in the dielectric performance. 相似文献
17.
The characteristics of the p–n junction between vertically aligned ZnO nanorods and polyaniline (PANI) thin film were investigated. The rectifying behavior of the I–V curve of ZnO/PANI diode was verified with assembled ZnO/PANI structures. The cut-in voltage of the p–n junction was found to be around 0.5 V and the reverse breakdown voltage was about ?27 V. In addition, the effects of UV illumination and NH3 exposure on the I–V characteristics of ZnO/PANI configuration were also investigated. 相似文献
18.
Effect of working pressure and temperature on ZnO film deposited on free-standing diamond substrates
《中国有色金属学会会刊》2006,16(B01):302-305
The structure characteristic and electric performance of ZnO film deposited on nucleation side of free-standing diamond substrates under different heating temperatures (Th) of substrate and working pressures (p) were studied. The structure of the ZnO films tested by X-ray diffraction shows that ZnO film of high c-axis orientation is deposited on the nucleation side of free-standing diamond substrate which is extremely smooth when Th=250 °C and p=0.4 Pa. After annealing at 480 °C in N2 atmosphere, the SEM and the AFM analyses demonstrate that the c-axis orientation of ZnO film is obviously enhanced. The resistivity of ZnO films also increases up to 8×105 Ωcm which is observed by I–V test. 相似文献
19.
Aligned ZnO nanorod arrays and oriented ZnO nanoplates were synthesized on Si and Al substrates, respectively, using a hydrothermal method without any surfactant. The process involved the deposition of ZnO seeds on the substrate and the oriented growth of ZnO nanostructure in aqueous solution. The ZnO seeds were indispensable for the alignment of ZnO nanorods and TEM and XRD analysis confirmed that the ZnO rods are single crystalline grown along [001] direction. Al substrate caused formation of (001) surface dominated ZnO nanoplates, in which ZnO preferential growth direction was suppressed. The photoluminescence spectra of the as-grown ZnO products were measured to indicate their structural and optical quality. These oriented ZnO nanostructures are expected to be prospectively applied in nanodevices fabrication. 相似文献
20.
Aaron Dodd Allan McKinley Takuya Tsuzuki Martin Saunders 《Journal of Alloys and Compounds》2010,489(2):L17-L21
In this study, we have investigated the optical and photocatalytic properties of nanoparticulate (TiO2)x(ZnO)1?x powders that were synthesised by mechanochemical processing. The objective was to establish the suitability of these powders for use as optically transparent ultraviolet light screening agents. It was found that the photocatalytic activity of single phase ZnO can be substantially reduced through the incorporation of TiO2 at the cost of a comparatively minor decrease in optical transparency. The composition given by (TiO2)0.10(ZnO)0.90 was characterised by a photocatalytic activity that was approximately 20% of that exhibited by the ZnO powder synthesised using similar processing conditions. These results demonstrate that (TiO2)x(ZnO)1?x powders synthesised by mechanochemical processing are potentially useful as optically transparent ultraviolet light screening agents. 相似文献