共查询到20条相似文献,搜索用时 15 毫秒
1.
D. A. Romanov E. A. Budovskikh V. E. Gromov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(6):1112-1117
The surface topography and structure of copper layers exposed to multiphase plasma jets of products of electrical explosion
of molybdenum and copper foils are studied using profilometry and scanning electron and light microscopy. Such treatment allows
deposition of either layered coatings or alloyed composite layers. It is found that the surface layer roughness parameter
is R
a
= 3.2−4.0 μm. The thickness of some copper and molybdenum layers of coatings is 15–20 μm. Electroexplosive alloying produces
layers 25 μm thick. Sizes of copper inclusions in the molybdenum matrix near the surface of such layers vary from 30 nm to
1–2 μm. 相似文献
2.
Salvatore Giuffrida Guglielmo G. Condorelli Lucia L. Costanzo Giorgio Ventimiglia Raffaella Lo Nigro Maria Favazza Enrico Votrico Corrado Bongiorno Ignazio L. Fragalà 《Journal of nanoparticle research》2007,9(4):611-619
Liquid Phase Photo-Deposition (LPPD) technique has been used to obtain both colloidal particles and thin films of metallic
and chloride nickel from solutions of only precursor Ni(acac)2 (acac=2,4-pentandionato). Metallic nickel was obtained from ethanol solutions by direct nickel(II) photoreduction at 254 nm
and by acetone sensitised reaction at 300 nm. In this latter process the rate was higher than in the first one. NiCl2 was formed from CCl4 solution by a solvent-initiated reaction. TEM analysis, performed on colloidal particles of nickel, showed that their dimensions
are in the range 2–4 nm. The films did not present carbon contamination and were characterized by AFM, XPS and GIXRD. Metallic
films consisted of particles of 20–40 nm that are the result of the aggregation of smaller crystallites (4–5 nm). Larger agglomerations
(around 200 nm) have been observed for NiCl2 films. 相似文献
3.
A. V. Varganov E. A. Vopilkin P. P. Vysheslavtsev Yu. N. Drozdov Yu. N. Nozdrin S. A. Pavlov A. E. Parafin V. V. Talanov 《JETP Letters》1996,63(8):644-650
The crystal structure and transport properties of epitaxial c-oriented YBa2Cu3O7−x
films are investigated for high-T
c layer thicknesses from 5 to 300 nm. The films were prepared by laser deposition. Films less than 30 nm thick become predominantly
single-domain in the direction of the c axis. As the thickness decreases, the orthorhombicity parameter of the YBaCuO lattice decreases, which correlates with the
critical temperature degradation observed in films less than 9 nm thick. The obtained thickness dependence of the effective
microwave surface resistance of a YBaCuO film agrees well with the computational result obtained in the framework of local
electrodynamics for samples with a constant microwave conductance.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 8, 608–613 (25 April 1996) 相似文献
4.
Nanostructured nonstoichiometric vanadium carbide VC0.87 was obtained in powdered form using the ordering effect. The composition, structure, and properties of the carbide were studied
by chemical and thermogravimetric analysis, gas chromatography, x-ray diffraction, optical and electronic microscopy, electron-positron
annihilation, magnetic susceptibility, and microhardness methods. Nanostructured vanadium carbide VC0.87 possesses the crystal structure of the cubic ordered phase V8C7 with space group P4332. Vanadium carbide nanocrystallites are shaped in the form of 400–600 nm in diameter and 15–20 nm thick curved petals. The
surface layer of the nanocrystallites contains defects of the vacancy agglomerate type. The microhardness of vanadium carbide,
obtained by vacuum sintering of VC0.87 nanopowder was 60–80 GPa, which is 3–4 times greater than the microhardness of coarse-grained vanadium carbide with the same
composition and close to the hardness of diamond.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 6, 436–442 (25 March 1999) 相似文献
5.
The absorption spectra and the melting and crystallization kinetics of CuCl nanocrystals in glass are investigated in the
range of particle radii 1–30 nm. Three discontinuities are found on the curves representing the size dependence of the melting
point T
m(R) and the crystallization point T
c(R). As the particle radius gradually decreases from 30 nm in the range R⩽12.4 nm there is a sudden 60° drop in the temperature T
c in connection with the radius of the critical CuCl nucleus in the melt. A 30° drop in T
m is observed at R=2.1 nm, and a second drop of 16° in the temperature T
c is observed for CuCl particles of radius 1.8 nm. The last two drops are associated with changes in the equilibrium shape
of the nanoparticles. In the range of smaller particles, R⩽1.34 nm the T
c(R) curve is observed to merge with the T
m(R) curve, owing to the disappearance of the work of formation of the crystal surface during crystallization of the melt as
a result of the zero surface tension of CuCl particles of radii commensurate with the thickness of the effective surface layer.
An increase in the size shift of the exciton energy is observed in this same range of CuCl particle radii (1–1.8 nm). The
size dependence of the melting and crystallization temperatures of the nanoparticles is attributed to variation of the free
energy in the surface layer of a particle.
Fiz. Tverd. Tela (St. Petersburg) 41, 310–318 (February 1999) 相似文献
6.
A. I. Ulyanov A. A. Chulkina A. L. Ulyanov V. A. Volkov A. V. Zagainov 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(7):830-833
Phase transformations and aspects of alloying the phases of alloys of cementite composition, alloyed with chromium and nickel in the state immediately after mechanical synthesis and subsequent annealing, are studied. It is shown that cementite after mechanical synthesis is basically alloyed with chromium, while the amorphous phase is alloyed with chromium and nickel. Cementite produced upon the crystallization of the amorphous phase at Tann = 300°C is enriched with nickel. At medium temperatures of annealing, the cementite regions with the highest nickel content decompose to form para- or ferromagnetic austenite. 相似文献
7.
A. D. Pogrebnyak A. A. Drobyshevskaya V. M. Beresnev M. K. Kylyshkanov T. V. Kirik S. N. Dub F. F. Komarov A. P. Shipilenko Yu. Zh. Tuleushev 《Technical Physics》2011,56(7):1023-1030
A new type of nanocomposite Ti-Al-N/Ni-Cr-B-Si-Fe-based coatings 70–90 μm thick produced by combined magnetron sputtering
and a plasma detonation technology is created and studied. Phases Ti3AlN + Ti3Al2N2 and the phases caused by the interaction of plasma with a thick Al3Ti + Ni3Ti coating are detected in the coatings. The TiAlN phase has a grain size of 18–24 nm, and other phases has a grain size of
35–90 nm. The elastic modulus of the Ti-Al-N coating is E = 342 ± 1 GPa and its average hardness is H = 20.8 ± 1.8 GPa. The corrosion rate of this coating is very low, 4.8 μg/year, which is about three orders of magnitude lower
than that of stainless steel (substrate). Wear tests performed according to the cylinder-surface scheme demonstrate high wear
resistance and high adhesion between the thick and thin coatings. 相似文献
8.
The SrRuO3 films (50 nm thick) grown by laser evaporation on (001)(LaAlO3)0.3 + (Sr2AlTaO6)0.7 substrates were under partially relaxed biaxial compressive mechanical stresses. The films consisted of crystallites with
lateral dimensions of 40–100 nm and a relative azimuthal misorientation of about 0.9°. Ferromagnetic ordering of spins in
the SrRuO3 films was manifested by a change in the slope of the temperature dependence of their electrical resistivity ρ at T ≈ 155 K. For a magnetic field H parallel to the measuring current, the maximum values (∼7.5%) of the magnetoresistance MR = [ρ(μ0
H = 5 T) − ρ(μ0
H = 0)]/ρ(μ0
H = 0) were observed at temperatures of about 100 K. At T = 95 K (μ0
H = 5 T), the anisotropic magnetoresistance of the films was 8% and increased by a factor of approximately 1.5 with decreasing
temperature to 4.2 K. 相似文献
9.
Deposition and alloying of metallic powders containing WC on a ferritic-pearlitic plain carbon steel have been investigated.
Metallic powder was injected into the melted surface layer of the samples under Argon atmosphere during the laser irradiation.
The sample surface was previously graphitizing treated to prevent energy loss by reflection. For comparison, irradiated samples,
without powder alloying, were also analysed. The coating layer is mainly composed of alloyed α-Fe; γ-austenite and non-magnetic
M3C carbide are also present. Partial dissolution of WC and the preliminary graphitizing treatment are the causes of the rather
high carbon concentration in γ-austenite. As it is to be expected this concentration decreases with increasing distance from
the external surface of the coating layer. 相似文献
10.
We have studied the growth characteristics, structure, and parameters of the epitaxial heterostructures (001)NdBa2Cu3O7−δ
/(100)SrTiO3/(001)NdBa2Cu3O7−δ
grown by laser ablation on a (100)LaAlO3 substrate with a thin (∼2 nm) YBa2Cu3O7−δ
intermediate layer. The use of an YBa2Cu3O7−δ
intermediate layer promotes layered growth of the (200 nm) NdBa2Cu3O7−δ
layer, whose free-surface roughness is 4–5 nm. The resistance of the NdBa2Cu3O7−δ
layers began to fall off abruptly at T=92 K, and at T≈87 K it vanished completely. The critical current density in the NdBa2Cu3O7−δ
layers at T=76 K exceeded 106 cm2 A/cm2. The dielectric constant of the (400 nm) SrTiO3 layer sandwiched between the NdBa2Cu3O7−δ
epitaxial layers grew by roughly threefold as the temperature was lowered in the interval 300–4.2 K. When a bias voltage
of ±2.5V was applied to the NdBa2Cu3O7−δ
electrodes, the relative dielectric constant of the (400 nm) SrTiO3 intermediate layer fell from 1150 to 400 (T=32 K, f=100 kHz). The conductivity of the SrTiO3 intermediate layer in the direction perpendicular to the substrate plane increased with temperature and the electric field
strength.
Fiz. Tverd. Tela (St. Petersburg) 41, 395–403 (March 1999) 相似文献
11.
I. S. Edelman E. A. Petrakovskaja D. A. Petrov S. M. Zharkov R. I. Khaibullin V. I. Nuzhdin A. L. Stepanov 《Applied magnetic resonance》2011,40(3):363-375
Fused silica plates have been implanted with 40 keV Co+ or Ni+ ions to high doses in the range of (0.25–1.0) × 1017 ions/cm2, and magnetic properties of the implanted samples have been studied with ferromagnetic resonance (FMR) technique supplemented
by transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. The high-dose implantation
with 3d-ions results in the formation of cobalt and nickel metal nanoparticles in the irradiated subsurface layer of the SiO2 matrix. Co and Ni nanocrystals with hexagonal close packing and face-centered cubic structures have a spherical shape and
the sizes of 4–5 nm (for cobalt) and 6–14 nm (for nickel) in diameter. Room-temperature FMR signals from ensembles of Co and
Ni nanoparticles implanted in the SiO2 matrix exhibit an out-of-plane uniaxial magnetic anisotropy that is typical for thin magnetic films. The dose and temperature
dependences of FMR spectra have been analyzed using the Kittel formalism, and the effective magnetization and g-factor values have been obtained for Co- and Ni-implanted samples. Nonsymmetric FMR line shapes have been fitted by a sum
of two symmetrical curves. The dependences of the magnetic parameters of each curve on the implantation dose and temperature
are presented. 相似文献
12.
Laser alloying of Ni–P electroless deposited layer with aluminum substrate was carried out by Nd–YAG pulsed laser. The phase composition and microstructure of the alloyed layers produced by different laser power densities were identified by X-ray diffractionary (XRD), scanning electron microscope (SEM) accompanied by energy dispersion X-ray analysis (EDS) and transmission electron microscope (TEM). Furthermore, the surface roughness of the alloyed layers was characterised by confocal laser scanning microscope (CLSM). The results showed that the characteristic dendritic or lamellar microstructures were observed in the alloyed layers. The phase constituents of the alloyed zones were intermetallic compounds of nickel–aluminum NiAl, Al3Ni and Al3Ni2, as well as some non-equilibrium phases and amorphous phases depending on the employed laser power density. As a result, the microhardness of the alloyed layer with Ni–P amorphous phases formed at laser power density 5.36×109 W/m2 reached to HV0.1 390. 相似文献
13.
Boiling occurs in a solution of oxygen and fullerenes in CCl4 upon optical pumping of C60 upon the fast appearance of incandescent fullerenes in cold solvent. Upon single-photon absorption, a spherical zone of the
critical state of CCl4 is formed within 5 ns (with a diameter of 22–25 nm, P
cr ∼ 45 atm, and T
cr ∼ 556 K). This spherical zone (gas-bubble nucleus) expands to a diameter of ∼100–400 nm for 2–5 ns. If the external pressure
(natural or artificial) is rapidly released, the bubble accelerates and emerges into a vacuum chamber within 0.7–25 μs (the
length of the passage is 0.1–5 cm depending on the construction of the singlet oxygen generator). We note that singlet oxygen
appears 50 ns after the absorption of a photon by fullerene (i.e., inside of the almost formed gas bubble that only begins
to emerge from the liquid to a low-pressure gas region). 相似文献
14.
B. M. Gorelov 《Journal of Experimental and Theoretical Physics》1999,89(2):311-320
The mechanisms for defect formation stimulated by the adsorption of water molecules in the surface of YBa2Cu3O7 ceramic are studied, together with the types of defects and their distributions. It is found that a water layer physically
bound to the surface reduces the rates of annihilation and capture of positrons, changes the amount of barium and copper on
the surface by a factor of two, and inhibits diffusive jumps of nickel atoms. A layer of adsorbed water excites subthreshold
formation of 1021 cm−3 interstitial Ba and Cu1 atoms and transitions of oxygen from O1 to O5, and vice versa in the volume of crystallites, and the migration of defects and accumulation of Ba atoms in the surface layer, which block
diffusive jumps of Ni within the volume of the crystals. These effects are related to the excitation of collective, low-frequency
weakly damped motion of heavy holes in the crystal volume when defects are formed on the surface by physically adsorbed H2O molecules, which is accompanied by Coulomb repulsion of cations from intermediate layers into interstitials and the migration
of defects in the field of the collective excitations.
Zh. éksp. Teor. Fiz. 116, 586–603 (August 1999) 相似文献
15.
A. D. Korotaev D. P. Borisov V. Yu. Moshkov S. V. Ovchinnikov K. V. Oskomov Yu. P. Pinzhin V. M. Savostikov A. N. Tymentsev 《Russian Physics Journal》2007,50(10):969-979
Electron microscopy, x-ray diffraction analysis, and micro-and nanohardness measurements were used to investigate the interrelations
between the fine structure and the variations in strength properties of nanostructured and nanocomposite Ti-Si-B-N coatings with high oxygen and carbon contents. It has been shown that under the conditions of low-temperature (T = 200°C)
coating deposition, a two-level grain structure forms with {200} texture and grains 0.1–0.3 μm in size fragmented into subgrains
15–20 nm in size. As the silicon content is increased, textureless coatings with the crystal phase grain size less than 15
nm and high amorphous component or coatings of amorphous-crystalline structure are produced. At coating deposition temperatures
of 400–450°C, a nanocomposite structure with a grain size d = 10–15 nm and no texture is observed. For all test compositions
and conditions of coating production, a Ti
1−x
Si
x
N crystal phase with the lattice parameter a = (0.416–0.420) ± 0.001 nm has been detected. For optimum coating compositions
and synthesis conditions, the hardness is over 40–50 GPa. It has been supposed that superhardness can be attained with multiphase
grain-boundary interlayers of thickness more than 1 nm.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 13–23, October, 2007. 相似文献
16.
The results of a study on the behavior of macrocomponents and admixtures at directed crystallization of two specimens of the
Fe-Ni-S (Pt, Pd) system are presented in this paper. The composition of the specimens belonged to the areas of primary crystallization
of a monosulphide solid solution ((Fe
z
Ni1 − z
)S1 + δ) and taenite (Fe-Ni solid solution with the structure γ-Fe), which were similar in composition to nickel concentrate and
nickel matte from the Norilsk Mining and Metallurgical Company (MMC). In this paper, data on the component distribution along
the crystallized specimens are given, and the dependence of the component distribution coefficients on the melt composition
along the crystallization path is determined. The conditions under which one-phased crystallization becomes the crystallization
of binary eutectics and then transforms to a four-phased invariant reaction are also determined. Some bounds of the possibility
to use crystallization processes for the separation of phases and components in the investigated system in a quasi-equilibrium
regime of specimen solidification are analyzed. 相似文献
17.
F. C. Fonseca R. F. Jardim M. T. Escote P. S. Gouveia E. R. Leite E. Longo 《Journal of nanoparticle research》2011,13(2):703-710
In this work, we report on the magnetic properties of nickel nanoparticles (NP) in a SiO2–C thin film matrix, prepared by a polymeric precursor method, with Ni content x in the 0–10 wt% range. Microstructural analyses of the films showed that the Ni NP are homogenously distributed in the SiO2–C matrix and have spherical shape with average diameter of ~10 nm. The magnetic properties reveal features of superparamagnetism
with blocking temperatures T
B ~ 10 K. The average diameter of the Ni NP, estimated from magnetization measurements, was found to be ~4 nm for the x = 3 wt% Ni sample, in excellent agreement with X-ray diffraction data. M versus H hysteresis loops indicated that the Ni
NP are free from a surrounding oxide layer. We have also observed that coercivity (H
C) develops appreciably below T
B, and follows the H
C ∝ [1 – (T/T
B)0.5] relationship, a feature expected for randomly oriented and non-interacting nanoparticles. The extrapolation of H
C to 0 K indicates that coercivity decreases with increasing x, suggesting that dipolar interactions may be relevant in films with x > 3 wt% Ni. 相似文献
18.
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
19.
Precision structural studies of layering of perfect crystals Bi
2
Sr
2−x
La
x
CuO
6+δ
(BSLCO) ∼ 10 μm thick, grown by free growth within crystallized melt cavities, detect a macrolayer structure with each layer up to 0.1 μm thick. In the lanthanum concentration range x = 0.6−0.8, only modulation layering is observed. In the concentration range
x = 0.3−0.5, either layers with two different lanthanum concentrations, but with the same modulated superlattice type, or
layers with the same lanthanum concentration, but with two different modulated superlattice types are observed. At low lanthanum
concentrations (0 < x < 0.26), layering into two or even three layer types with different lanthanum concentrations are almost always observed.
Modulation suppression when lead is added to a mixture leads to the same layered structure of samples, but with appreciable
variations in lattice parameters in the ab plane of individual layers and a and b axis rotation by several degrees with respect to each other in these layers. Thus, the superlattice in BSLCO single crystals
stabilizes their composition in the ab plane, and inevitable variations in growth conditions lead to the layered structure of such crystals.
Original Russian Text ? V.P. Martovitsky, A. Krapf, 2008, published in Kratkie Soobshcheniya po Fizike, 2008, Vol. 35, No.
3, pp. 29–38. 相似文献
20.
A.?Ya.?Kha?rullina T.?V.?Ol’shanskaya V.?A.?Tolmachev T.?A.?Zhevlakova D.?A.?Yavsin V.?M.?Kozhevin S.?A.?Gurevich 《Optics and Spectroscopy》2010,108(5):735-742
It is found that a significant spread in the optical constants of metals reported by different authors is caused by differences
in the sample preparation methods, measurement conditions, and methods of calculation of sought parameters, as well as by
the oxidation effect. It is shown that the optical constants of metals in films 80–120 nm thick on silicon substrates with
scattering below 10−4 are determined with minimal errors. The reflectance of these mirrors calculated from the optical constants found by the most
accurate ellipsometric method coincides with the experimental value within the measurement accuracy. Low values of k(λ) obtained for thin layers in some works using the methods based on the measurement of the coherent transmittance and regular
reflectance are explained by disregarded scattering and luminescence. The spectra of the imaginary part of the complex refractive
index of copper, nickel, and copper oxide determined by us by the proposed methods for thin nanostructured layers taking into
account the scattering and luminescence coincide with the most correct data for thick films in the spectral range of 325–633
nm. For thin palladium and palladium oxide layers, the variations in k(λ) are caused by the oxidation of metal granules and disregarded luminescence for thick oxide layers in the long-wavelength
spectral region. The maximal difference in the imaginary part of the complex refractive index of copper and nickel for thin
nanostructured layers are observed in the region of plasmon resonances, whose positions and amplitudes depend on the degree
of asphericity, the shape, and the degree of order of particles and their aggregates, which shift the plasmon resonances of
films to longer wavelengths with respect to spherical particles. 相似文献