共查询到20条相似文献,搜索用时 31 毫秒
1.
D. Nohavica 《Czechoslovak Journal of Physics》1997,47(7):699-705
Pre-diffusion limited technique of liquid phase epitaxy is used for preparation of quaternary solid solution Ga
x
In1−x
As
y
P1−y
and binary InP. Surface morphology of the layers prepared at this condition has been compared with those prepared by conventional
LPE. Quaternary strained layers with composition near to Ga0.21In0.79As0.75P0.25 were grown with perpendicular lattice mismatch up to 1.6% in compression, on the InP substrates of (100) orientation. The
used epitaxial technique has been modified for perspective attempt to heal the growth interfaces. Modification was tested
by InP growth.
Presented at the 6th Joint Seminar “Development of Materials Science in Research and Education”, Karlštejn, Czech Republic,
17–19 September 1996. 相似文献
2.
B. N. Zvonkov O. V. Vikhrova Yu. A. Danilov Yu. N. Drozdov A. V. Kudrin M. V. Sapozhnikov 《Physics of the Solid State》2010,52(11):2267-2270
The effect of elastic stresses (compressive, tensile) on the magnetic properties of epitaxial GaMnAs layers prepared by laser
deposition of solid-state targets in a gas atmosphere on different buffer sublayers (In
x
Ga1 − x
As and In
x
Ga1 − x
P) and substrates (GaAs, InP) has been investigated. It has been established from the investigations of magnetic-field dependences
of the Hall resistance that all layers exhibit ferromagnetic properties with the Curie temperature ∼50 K. It has been shown
that, in the case of tensile stresses in GaMnAs layers (In
x
Ga1 − x
As and In
x
Ga1 − x
P buffers and InP substrate), the anomalous Hall effect shape demonstrates a predominant orientation of the easy-magnetization
axis in the growth direction, unlike the GaMnAs layers prepared on a GaAs substrate (with compressive stresses), which demonstrate
the predominance of the component of the magnetization vector in the layer plane. 相似文献
3.
H. Sakakima M. Satomi Y. Sugita Y. Kawawake 《Journal of magnetism and magnetic materials》2000,210(1-3)
Spin valves having thin oxide layers in the pinned and/or free layers were prepared by sputtering. MR ratios of the spin valves were increased from 8.1 to 11.9% by inserting the oxide layer into the pinned layer in Ta/PtMn/CoFe/Cu/CoFe/Ta spin valves. MR ratio of 13.9% and considerably large sheet ΔR of 2.55 Ω were obtained in the PtMn-based spin valves having the oxide layer in the pinned and free layer. Larger MR ratio of 17.3% and the sheet ΔR of 1.3 Ω were obtained in the PtMn-based dual-type spin valves having the oxide layer in both pinned layers. α-Fe2O3 based spin valves having thin oxide layers were also prepared. MR ratios of the spin valves were increased from 11.9 to 14.3% by inserting the oxide layer into the free layer in α-Fe2O3/CoFe/Cu/CoFe/Ta spin valves. The enhancement of the MR ratios may be attributed to the specular scattering effect of the conduction electrons by the thin oxide layers. 相似文献
4.
J. Balogh D. Kaptás L. F. Kiss T. Kemény L. Bujdosó I. Vincze 《Hyperfine Interactions》2006,169(1-3):1343-1347
Magnetic multilayers of 57Fe with nominal thickness, T
nom, between 0.4 and 1.0 nm separated by 3.0 nm Al spacer layers were prepared by alternate deposition of the constituents in
high vacuum. The samples were investigated at 4.2 K in external magnetic field. A fraction of Fe atoms corresponding to about
0.3 nm equivalent Fe-thickness was found to mix into the Al spacer. The extremely strong magnetic anisotropy observed for
T
nom < 0.8 nm is attributed to Fe layers of approximately two atomic planes thick. The anisotropy decreases considerably after
the building up of the third Fe atomic layer starts at T
nom = 0.8 nm, but full saturation was not achieved even for T
nom = 1 nm and 3 T magnetic field applied perpendicularly to the sample plane. 相似文献
5.
Preparation and mechanical properties of layers made of recombinant spider silk proteins and silk from silk worm 总被引:1,自引:0,他引:1
F. Junghans M. Morawietz U. Conrad T. Scheibel A. Heilmann U. Spohn 《Applied Physics A: Materials Science & Processing》2006,82(2):253-260
Layers of recombinant spider silks and native silks from silk worms were prepared by spin-coating and casting of various solutions.
FT-IR spectra were recorded to investigate the influence of the different mechanical stress occurring during the preparation
of the silk layers. The solubility of the recombinant spider silk proteins SO1-ELP, C16, AQ24NR3, and of the silk fibroin
from Bombyx mori were investigated in hexafluorisopropanol, ionic liquids and concentrated salt solutions. The morphology and thickness of
the layers were determined by Atomic Force Microscopy (AFM) or with a profilometer. The mechanical behaviour was investigated
by acoustic impedance analysis by using a quartz crystal microbalance (QCMB) as well as by microindentation.
The density of silk layers (d<300 nm) was determined based on AFM and QCMB measurements. At silk layers thicker than 300 nm
significant changes of the half-band-half width can be correlated with increasing energy dissipation. Microhardness measurements
demonstrate that recombinant spider silk and sericine-free Bombyx mori silk layers achieve higher elastic penetration modules EEP and Martens hardness values HM than those of polyethylenterephthalate (PET) and polyetherimide (PEI) foils. 相似文献
6.
Ali Durmus Ahmet Kaşgöz Christopher W. Macosko 《Journal of Macromolecular Science: Physics》2013,52(3):608-619
In this study, mechanical properties of the linear low‐density polyethylene (LLDPE)/org‐clay nanocomposites prepared by melt processing were investigated. Aspect ratio (A f ) of the clay layers were estimated by using the Halpin‐Tsai (H‐T) micromechanical model based on the enhancement of the Young's modulus (E) with the clay loading (φ). Strength of interfacial interactions (τ and B parameters) between the clay layers and polymer chains were also quantified by two indirect modeling approaches based on the improvement in tensile strength (or yield stress) of the nanocomposite samples. Interfacial strength parameters, τ and B, were found as about 5 MPa and 17.3, respectively. The average value of A f was calculated as ~35 by the H‐T model. In the TEM study, it was observed that the nanocomposite samples showed mixed morphology that could be defined as some exfoliated layers, intercalated clay stacks, and two to three layered tactoids present together within the samples. An estimated A f value was also confirmed by the TEM study. On the other hand, it was also shown that the A f value is consistent with previously reported values calculated by the modeling of melt rheological data of samples obtained from dynamic oscillatory shear measurements. 相似文献
7.
Chao Pan Li Dong Li-Qin Ge Jing Wang Zhong-Ze Gu 《Journal of Macromolecular Science: Physics》2013,52(1):92-105
Compared to conventional film photocatalysts, fiber photocatalyst has a greater surface-to-volume ratio and a 3-D open structure that allows its surface active sites to be accessible for reactants more easily and effectively. However, TiO 2 powder (Degussa P25), by itself, cannot be prepared in the form of fibers, but with the help of a polymer nanofiber, TiO 2 particles can be immobilized in a fibrous network of polyelectrolyte. Here, hybrid multilayered hollow nanofibers (HMHNFs) composed of TiO 2 /polyelectrolyte (PE) have been prepared by a combination of a electrospinning method and layer-by-layer (LBL) technology. The results show that both the average diameter and the wall thickness of the HMHNFs can be well controlled by the template, as well as the number of coating layers. The dried morphology of the obtained HMHNFs is dependent on the inner deposited numbers of the polyelectrolyte layers. When compared with other nanostructured TiO 2 materials, such as commercial TiO 2 nanoparticles (P25, Degussa) and TiO 2 films, the hollow TiO 2 /PE hybrid nanofibers exhibited higher photocatalytic activities. 相似文献
8.
A. I. Skvortsov N. E. Khlebova N. I. Kozlenkova B. D. Zheleznyakov J. Růžička J. Prachařová F. Samek 《Czechoslovak Journal of Physics》1985,35(9):1033-1048
Nb-Ge layers with continuous change of chemical and phase composition were prepared by the d.c. sputtering method. The dependence of critical temperatureT
c on phase composition, Ge-content, lattice imperfections and composition irregularities were studied. Films with highT
c contain beside the A-15 Nb3Ge phase also the hexagonal and tetragonal modification of the Nb5Ge3 phase. Correlation betweenT
c and Nb3Ge phase composition determined from the lattice parameter was found. In samples with highestT
c the lattice parametera
0=0·5135 nm corresponding to 22–23 at.% of germanium was determined. 相似文献
9.
《Composite Interfaces》2013,20(5):465-475
The oligomer of bis-phenol A (oligo-PC) with M w = 1300 and bis-phenol A polycar-bonate (PC) with M w = 20 000 were deposited onto E-glass surface using SiCl4 as the grafting and cross-linking agent. Thickness of the deposited layers was varied from 30 to 106 nm and the layers were investigated as prepared and after thermal annealing at 245°C for 10 min in the air. Vibrational piezoelectric resonator technique and the speed of Rayleigh wave measurement were used to determine elastic moduli of the ultra thin layers deposited on flat E-glass substrate as a function of their thickness. In all cases, increase of the Young modulus of the interphase, E i, with decreasing layer thickness, t i, was observed. At a given thickness, the E i of PC layer was significantly lower than that for the oligo-PC layer. Thermal annealing of the deposited PC layer resulted in a significant increase of its E i compared to the as received layer. No significant change was observed for oligo-PC interphases. Increase of the shear strength of the interface, τ a, with reducing interphase thickness, t i, was observed. The observed increase of E i with the decreasing t i was ascribed to the reduction of the molecular mobility of chains near solid surface compared to their mobility in the bulk. Most probably, the observed increase of E i after thermal annealing of PC was caused by rearrangement of both segment density distribution in individual PC coils near the solid surface and cooperative rearrangements of multiple PC chains. Since the oligomers attached to the surface attained presumably more regular extended conformations with lower conformation entropy compared to the PC random coils, the effect of thermal annealing was negligible. In agreement with theoretical predictions, increase of E i at the same extent of interfacial interactions resulted in the observed increase of the τ a measured using the single embedded fiber test. 相似文献
10.
Back contact–absorber interface modification by inserting carbon intermediate layer and conversion efficiency improvement in Cu2ZnSn(S,Se)4 solar cell
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Fangqin Zeng Kaiwen Sun Li Gong Liangxing Jiang Fangyang Liu Yanqing Lai Jie Li 《固体物理学:研究快报》2015,9(12):687-691
Carbon layers have been employed as intermediate layers between Mo back contact and Cu2ZnSn(S1–xSex)4(CZTSSe) absorber film prepared by sol–gel and post‐selenization method. Carbon layers with appropriate thickness can significantly inhibit the formation of MoSe2 and voids at bottom region of the absorber, and therefore reduce the series resistance remarkably. The conversion efficiency can be boosted by the introducing of the carbon layer from 6.20% to 7.24% by enhancement in short current density, fill factor and open voltage in comparison to the reference sample without carbon layer. However, excess thickness of carbon layer will worse device performance due to the deteriorated absorber crystallinity. In addition, the time‐resolved photoluminescence analysis shows that inserting the carbon layer with suitable thickness does not introduce recombination and lower minority lifetime. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
11.
The barium strontium titanate ceramics Ba1 − x
Sr
x
TiO3 with a spatially variable composition has been prepared according to the thick film technology (tape casting). The strontium
content over the film thickness is varied from 0 to 30 mol %. The structure and polarization characteristics of the samples
prepared have been investigated. It has been found that the polarization characteristics of multilayer structures are determined
by the ratio between the thicknesses of layers with different compositions and by their properties. No shift of the hysteresis
loops in the graded thick Ba1 − x
Sr
x
TiO3 (
x
= 0–0.3) films has been revealed. The results obtained have been analyzed in the framework of modern theoretical approaches. 相似文献
12.
Jaroslav Bruncko Andrej Vincze Marie Netrvalova Frantisek Uherek Pavol ?utta 《Applied Physics A: Materials Science & Processing》2010,101(4):665-669
The contribution deals with ZnO thin layers doped by nitrogen which were prepared by pulsed laser deposition in N2O ambient atmosphere. Our approach is based on ablation of undoped ZnO target in active atmosphere containing N2O gas without any supporting excitation equipment in parallel. Ablation of ZnO target was performed at different pressures
(1–32 Pa) of N2O ambient atmosphere by pulsed Nd:YAG laser (at 355 nm). Layers of ZnO were grown on different substrates (Si, sapphire, fused
silica) and their properties were investigated by various analytical methods: scanning electron microscopy (SEM), secondary
ion mass spectroscopy (SIMS), X-ray diffraction (XRD), and optical transmission spectroscopy. The results confirmed incorporation
of nitrogen into ZnO layers and its concentration was pressure dependent. According to SIMS analysis, there is a certain pressure
level (above 10 Pa) when the presence of N becomes negligible. Transmittance spectra showed increasing of the optical band
gap (E
g) according to the pressure of N2O. 相似文献
13.
Co/Ti multilayers with wedge-shaped Co or Ti sublayers were prepared using UHV (5×10−10 mbar) DC/RF magnetron sputtering. The planar growth of the Co and Ti layers was confirmed in situ by X-ray photoelectron spectroscopy. Cobalt sublayers grow on sufficiently thick titanium sublayers in the soft magnetic nanocrystalline phase up to a critical thickness dcrit3.0 nm. For a thickness greater than dcrit, the Co sublayers undergo a structural transition to the polycrystalline phase with much higher coercivity. Furthermore, for the Co/Ti multilayers with nanocrystalline Co sublayers with dCo=2.7 nm we have observed a significant drop of the coercivity — typically from Hc3.5 kA/m to Hc0.2 kA/m — for Ti thickness dTi0.35 nm. The above effect could be explained by the existence of a minimum Ti sublayer thickness (dmin0.35 nm), which is required for the nanocrystalline growth of Co, and/or the formation of quasi-continuous non-magnetic layers for dTidmin giving rise to a decrease of the exchange energy between Co sublayers. Magnetic domains and walls studies revealed the structural transitions of the Co sublayers. 相似文献
14.
Hyung-Joon Cho Poong-Gok Hwang Dongwoon Jung 《Journal of Physics and Chemistry of Solids》2011,72(12):1462-1466
TiO2 hollow nanospheres were prepared using silicon oxide as a template. N-doped titanium oxide hollow spheres, TiO2−xNx were synthesized by reacting TiO2 hollow spheres with thiourea at 500 °C. XRD and XPS data showed that oxygen was successfully substituted by nitrogen through the nitrogen-doping reaction, and finally N-doped TiO2 hollow spheres were formed. The N-doped TiO2 hollow spheres showed new absorption shoulder in visible light region so that they were expected to exhibit photocatalytic activity in the visible light. The photocatalytic activity of N-doped TiO2 hollow spheres under visible light was similar to that of normal spherical TiO2−xNx in spite of the structural difference. 相似文献
15.
Manickam Sivakumar Atsuya Towata Kyuichi Yasui Toru Tuziuti Teruyuki Kozuka Masahiko Tsujimoto Ziyi Zhong Yasuo Iida 《Ultrasonics sonochemistry》2010,17(1):213-218
Fine particles of rutile TiO2 supporting nanosized particles of Pt were prepared by a simultaneous in situ sonochemical reduction and deposition method using a standing wave sonochemical reactor (SWSR). The mean diameter of sonochemically obtained Pt particles are of 2 nm. Following this sonochemical technique, rutile TiO2 was also deposited with different weight percentages of Pt. Catalytic function of the prepared composite catalysts were tested by the oxidation of CO to CO2. From the catalytic activity results, it has been found out that the catalysts prepared by the sonochemical method exhibited higher catalytic activity for CO oxidation, probably attributed to the higher Pt particle distribution achieved under sonication. Transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and diffuse reflectance spectroscopy (DRS) were employed to characterize the resulting material. 相似文献
16.
Oleksandr Romanyuk Keita Kataoka Fumihiko Matsui Ken Hattori Hiroshi Daimon 《Czechoslovak Journal of Physics》2006,56(3):267-276
The atomic structure of thin iron silicide film, grown epitaxially on the Si(111) surface, has been analyzed by means of the
three-dimensional RHEED Patterson function analysis. The iron-silicide-terminated surface with (2 × 2) periodicity has been
prepared by a solid-phase epitaxy method. 2 ML of Fe were deposited on the Si(111)-(7 × 7) surface and annealed at 500°C.
Three-dimensional Patterson function was calculated from series of φ-scanned RHEED intensity distributions converted to the k-space. The resulting model of γ-FeSi2 structure consists of two silicide layers faulted to each other with three relaxed Si adatoms above the H3 site. 相似文献
17.
The protective effects of 18 hydroxyl‐substituted Schiff bases (SchOHs) on the oxidative damage of naked DNA induced by 2,2′‐azobis(2‐amidinopropane hydrochloride) (AAPH) were reported, in which SchOHs were prepared by condensing hydroxyl‐substituted aromatic aldehydes and anilines. The extent of the oxidative damage of DNA was followed by measuring the formation of thiobarbituric acid reactive substance (TBARS). Some SchOHs bearing only one hydroxyl group (prepared by salicylic aldehyde) protected DNA by decreasing the formation rate of TBARS. Other SchOHs inhibited the oxidation of DNA for a period, resulting in an inhibition period (tinh) that was proportional to the concentration of SchOH, viz., tinh = (n/Ri)[SchOH]. Thus, the stoichiometric factor (n) can be calculated if the initiation rate (Ri) was known. The n value of an SchOH was closed to the summation of the n from every structural feature in this SchOH, indicating that the antioxidant activity of SchOH was contributed from every structural feature in the molecule. Furthermore, the large conjugative system and para‐hydroxyl at benzilidene were good for the antioxidant activity of SchOHs. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
18.
《Solid State Communications》1986,57(10):805-808
Thin layers of tin disulfide (SnS2) are chemically deposited on glass plates. In an optical investigation of SnS2 layers at room temperature a direct allowed transition at 2.54 eV was recognised. Indirect allowed transition was also observed with an energy gap of 2.28 eV and assisting phonon of 0.05 eV. The cost of one square meter of the coatings was estimated. SnS2 layers prepared by chemical deposition show comparable optical properties with that prepared by high vacuum evaporation technique. 相似文献
19.
ZnO nanoparticles were prepared by a simple chemical synthesis route. Subsequently, SiO2 layers were successfully coated onto the surface of ZnO nanoparticles to modify the photocatalytic activity in acidic or alkaline solutions. The obtained particles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS) and zeta potential. It was found that ultrafine core/shell structured ZnO/SiO2 nanoparticles were successfully obtained. The photocatalytic performance of ZnO/SiO2 core/shell structured nanoparticles in Rhodamine B aqueous solution at varied pH value were also investigated. Compared with uncoated ZnO nanoparticles, core/shell structured ZnO/SiO2 nanoparticles with thinner SiO2 shell possess improved stability and relatively better photocatalytic activity in acidic or alkaline solutions, which would broaden its potential application in pollutant treatment. 相似文献
20.
This article examines experimental results from a study of impulsive photoconductivity in layers of glasses of AsxSe100–x (30-@#@ 60). It was found that thermal and laser treatment (thermo- and photostructural changes) affect the character of relaxation processes in photoconduction in freshly prepared layers. It was also established that both annealing at temperatures near the softening point of the glass and laser irradiation with quantum energies exceeding the width of the forbidden band are accompanied by a change in the recombination lifetime of nonequilibrium carriers. It is concluded on the basis of empirical data that an efficient recombination channel complementary to the main channel (tunnel transition of the type 2D0D++D–) is present in freshly prepared layers. The latter is present in annealed layers. The additional recombination channel is related to the existence of homopolar bonds in binary arsenic selenides and is proven to exist by data on the effect of composition on photocurrent relaxation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 66–71, May, 1987. 相似文献