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991.
Epitaxy provides thin films in a perfect periodic structure. In heteroepitaxy the misfit may yield perfect pseudomorphic films or relaxed films, which may show the periodicities of the substrate and the film and their combinations. Then non-periodic defects like mosaics may appear, e.g., due to dislocations. Deviations from exact epitaxial positions in strictly periodic structures can be determined from diffraction intensities. For more complex surfaces, e.g., films with defects like mosaics or large superstructures or on substrates with steps such a strict determination is not possible. From the spot profile analysis of low energy electron diffraction (LEED) or X-ray data some structural information is available for these surfaces with defects. This new type of evaluation is demonstrated with spot profile analysis of LEED (SPA-LEED) for ultrathin Pb films on Si(1 1 1)7 × 7 surface, which grow even at 25 K epitaxially in a layer-by-layer growth mode. The analysis provides the first information on deviation from the exact epitaxial positions of the surface Pb atoms. A vertical shift of domains and an inclination between domains provides an explanation of the experimental results. 相似文献
992.
利用电化学方法在室温下成功地沉积了类金刚石(DLC)薄膜和非晶CNx薄膜,并 对制备条件进行了讨论.通过扫描电子显微镜、傅里叶变换红外光谱技术,分析了薄膜的表面形貌和化学结合状态.场发射测量结果表明:DLC膜和非晶CNx的开启场分别为88和 10V/μm;并且在23V/μm的电场下,DLC膜和非晶CNx膜的发射电流密度分别达到10 和037mA/cm2.
关键词:
电化学沉积
类金刚石薄膜
x薄膜')" href="#">CNx薄膜
场致电子发射 相似文献
993.
Thin films of the rare-earth metal Dy were grown on W(1 1 2) at room temperature and 570 K. Then the resultant film morphologies were characterised by LEED and STM. A series of novel film morphologies, including c(4 × 6), c(5 × 12) and (5 × 8) structures, were found that are unique among the rare-earth metals. High thermal stability was found for the Dy films (up to 1650 K, close to the melting point at 1685 K) such that the Dy atoms preserved an ordered structure and the Dy volatility was less than would be expected from its vapour pressure. This is an indication of strong electronic interactions between the Dy atoms and the W(1 1 2) substrate. 相似文献
994.
Z. Dohnálek 《Surface science》2006,600(17):3461-3471
Thin Pd films (1-10 monolayers, ML) were deposited at 35 K on a Pt(1 1 1) single crystal and on an oxygen-terminated FeO(1 1 1) monolayer supported on Pt(1 1 1). Low energy electron diffraction, Auger electron spectroscopy, and Kr and CO temperature programmed desorption techniques were used to investigate the annealing induced changes in the film surface morphology. For growth on Pt(1 1 1), the films order upon annealing to 500 K and form epitaxial Pd(1 1 1). Further annealing above 900 K results in Pd diffusion into the Pt(1 1 1) bulk and Pt-Pd alloy formation. Chemisorption of CO shows that even the first ordered monolayer of Pd on Pt(1 1 1) has adsorption properties identical to bulk Pd(1 1 1). Similar experiments conducted on FeO(1 1 1) indicate that 500 K annealing of a 10 ML thick Pd deposit also yields ordered Pd(1 1 1). In contrast, annealing of 1 and 3 ML thick Pd films did not result in formation of continuous Pd(1 1 1). We speculate that for these thinner films Pd diffuses underneath the FeO(1 1 1). 相似文献
995.
23Na nuclear magnetic resonance (NMR) spectroscopy of NaCl-exchanged polyamide (PA) films comparable to those of the active skin layer of many reverse osmosis (RO) membranes provides novel insight into the structural environments and dynamical behavior of Na+ in such films. Unsupported PA films were synthesized via interfacial polymerization of trimesoyl chloride in hexane and m-phenylenediamine in aqueous solution, and SEM, FT-IR, and 13C NMR data demonstrate successful thin film polymerization. Compositional data confirm this conclusion and demonstrate equal Na and Cl incorporation during NaCl exchange from aqueous solution. The 23Na NMR spectra for freshly made polymer samples exchanged in 1 M NaCl solution show significant relative humidity (RH) dependence. At near 0% RH, there are resonances for crystalline NaCl and rigidly held Na+ in the PA. With increasing RH, a resonance for solution-like dynamically averaged Na+ appears and above 51% RH is the only signal observed. The slightly negative chemical shift of this resonance suggests a dominantly hydrous environment with some atomic-scale coordination by atoms of the polymer. The greatly reduced 23Na T1 relaxation rates for this resonance relative to bulk solution and crystalline NaCl confirm close association with the polymer. Variable temperature 23Na NMR spectra for a sample equilibrated at 97% RH obtained from −80 to 20 °C show the presence of rigidly held Na+ in a hydrated environment at low temperatures and replacement of this resonance by the dynamically averaged signal at temperatures above about −20 °C. The results provide support for the solution–diffusion model for RO membranes transport and demonstrate the capabilities of multi-nuclear NMR methods to investigate molecular-scale structure and dynamics of the interactions between dissolved species and RO membranes. 相似文献
996.
A. D. Rata H. Braak D. E. Bürgler S. Cramm C. M. Schneider 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(4):445-451
We investigate the structure and magneto-transport
properties of thin films of the Co2Cr0.6Fe0.4Al
full-Heusler compound, which is predicted to be a half-metal by
first-principles theoretical calculations. Thin films are deposited
by magnetron sputtering at room temperature on various substrates in
order to tune the growth from polycrystalline on thermally oxidized
Si substrates to highly textured and even epitaxial on MgO(001)
substrates, respectively. Our Heusler films are magnetically very
soft and ferromagnetic with Curie temperatures up to 630 K. The total
magnetic moment is reduced compared to the theoretical bulk value, but
still comparable to values reported for films grown at elevated
temperature. Polycrystalline Heusler films combined with MgO barriers
are incorporated into magnetic tunnel junctions and yield 37%
magnetoresistance at room temperature. 相似文献
997.
D. Briassoulis 《Polymer Degradation and Stability》2007,92(6):1115-1132
The introduction and the expanding use of biodegradable materials represent a really promising alternative for enhancing sustainable and environmentally friendly agricultural activities in mulching and low-tunnel cultivation. The main challenges for the development of agricultural films biodegradable in the soil concern primarily the effects of ageing and degradation during the useful lifetime, which may cause premature losses in their mechanical performance. A set of Mater-Bi based biodegradable films was developed and tested, following the selective optimisation of some processing parameters of the film manufacturing along with the optimisation of the structural low-tunnel system design. The behaviour experienced during the experiments suggests that the so optimised biodegradable films perform in a way comparable to the corresponding LDPE films, within the period of their useful lifetime. Experimental investigation indicates that water and high temperatures do not affect the mechanical behaviour of the biodegradable films significantly, as it is experienced during the first period of their exposure to real field conditions. A high dose of UV radiation has detrimental effects, however, on the elongation at break of both mulching and low-tunnel films. These films are shown to be readily degraded within 4-6 months under irrigated agricultural soil conditions, indicating a high biodegradability rate. 相似文献
998.
Pietro Favia Victor H. Perez-Luna Thomas Boland David G. Castner Buddy D. Ratner 《Plasmas and Polymers》1996,1(4):299-326
Fluoropolymer films have been deposited in the glow and afterglow regions of radio frequency glow discharges fed with C2F6−H2 mixtures. Structure, growth rate, composition, and wettability of the films have been investigated by means of atomic force
microscopy, electron spectroscopy for chemical analysis, secondary ion mass spectrometry, and water contact angle measurements.125I labeled baboon fibrinogen in baboon plasma has been used to study the adsorption of the protein onto the films. Protein
retention, i.e., the binding affinity of the adsorbed protein, has been examined by elution with a sodium dodecyl sulfate
solution. Adsorption and retention of fibrinogen were correlated using multivariate statistical methods with the wettability,
the degree of film fluorination, and the CF
x
(1≤x≤3) group distribution of the coatings. This correlation identified the influence of each variable on the adsorption and retention
of fibrinogen onto these substrates. These variables or surface properties can be easily balanced by properly tuning the experimental
conditions of the glow discharge deposition process. 相似文献
999.
Vitamin B12-hyperbranched polymer was synthesized and characterized by UV-vis and NMR spectroscopy as well as DLS. The shape of hybrid polymer was also directly observed by TEM. Microenvironmental polarity around vitamin B12 derivative on the polymer was evaluated by UV-vis absorption peak with α-band of vitamin B12 chromophore. 相似文献
1000.
Controllable formation and properties of solid single-crystal micro-and nanoshells of various shapes (tubes and spirals, vertically
positioned rings and cylinders, and bent and trough-shaped cantilevers) are briefly reviewed, and new results are given. The
shells and complicated structures of prescribed size and shape are formed with the use of elastic energy of initial strained
SiGe/Si films of nanometer thickness and methods of highly selective and directed detachment of the films from the silicon substrates.
It is experimentally demonstrated that the diameters of the fabricated SiGe/Si nanotubes are several times smaller than the values predicted by the continuum elasticity theory. The properties of the shells
made of semiconductor and hybrid (metal-semiconductor and metal-dielectric-semiconductor) films and their applications in
micro-and nanoscale electrical engineering are discussed.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 6, pp. 114–128, November–December, 2006. 相似文献