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1.
The irradiation-induced silicide formation in ion beam-mixed layer of Au/Si(1 0 0) system was investigated by using 200 keV Kr+ and 350 keV Xe+ ions to fluences ranging from 8×1014 to 1×1016 ions/cm2 at room temperature. The thickness of Au layer evaporated on Si substrate was ∼500 Å. Rutherford backscattering spectrometry (RBS) experiments were carried out to study the irradiation effects on the mixed layers. We observed that at the fluence of 1×1016 Kr+/cm2 and starting from the fluence of 8×1014 Xe+/cm2, a total mixing of the deposited Au layer with Si was obtained. RBS data corresponding to the fluences of 1×1016 Kr+/cm2 and 8×1014 Xe+/cm2 clearly showed mixed layers with homogenous concentrations of Au and Si atoms which can be attributed to gold silicides.The samples irradiated to fluences of 1×1016 Kr+/cm2 and 1×1016 Xe+/cm2 were also analyzed by X-ray photoelectron spectroscopy (XPS). The observed chemical shift of Au 4f and Si 2p lines confirmed the formation of gold silicides at the surface of the mixed layers. Au2Si phase is obtained with Kr+ irradiation whereas the formed phase with Xe+ ions is more enriched in Si atoms. 相似文献
2.
Bernd Rauschenbach 《Journal of Materials Science》1986,21(2):395-404
Polycrystalline titanium was implanted with nitrogen ions at energies from 30 to 60 keV and with doses from 1 × 1016 to 1.5 × 1018 N+-ions cm–2 at room temperature. The implanted titanium layers were investigated by high-voltage electron microscopy and transmission high-energy electron diffraction. The formation of titanium nitride, titanium carbonitride and titanium carbide phases were considered in relation to their dependence on nitrogen ion implantation dose. In the dose range from 1 × 1016 up to 1.5 × 1018 N+-ions cm–2 the cubic phase -TiN
x
was formed. In the dose range between 1 to 2.5 × 1017 and 1.5 × 1018N+-ions cm–2 the tetragonal phase -Ti2N was found in addition to the -TiN
x
phase. The lattice structure of these titanium nitride phases is a function of the nitrogen ion implantation dose. Additionally, the presence of titanium carbonitrido TiC
y
O
x
and titanium carbide TiC
y
phases can be proved. The analysed titanium nitride, titanium carbUnitride and titanium carbide phases are represented in a state diagram as a function of implantation dose. 相似文献
3.
Thin films of InSe
x
were obtained by vacuum evaporation of polycrystalline materials onto substrates at moderate temperatures,T
s. Electrical properties of films grown from different stoichiometries of flash source materials are reported in this work. The temperature dependence of the conductivities shows two conduction regimes. The low temperature regime exhibits aT
–1/4 conductivity dependence which fits well, using the Mott model, with an average localized states density value ofN(E
F
) 8×1018cm–3eV–1. Hall measurements as a function of temperature show that the predominant conduction mechanism is scattering by grain boundaries in polycystalline films. 相似文献
4.
D. B. Chrisey J. S. Horwitz H. S. Newman M. E. Reeves B. D. Weaver K. S. Grabowski G. P. Summers 《Journal of Superconductivity》1991,4(1):57-60
We have explored the effect of 2-MeVH+ irradiation on the superconducting transport properties of thin films of YBa2Cu3O7–
[T
c, Jc(B=0; 77 K, 4.2 K), andR
s(36 GHz;T)]. The inductively measured critical temperatureT
c changed slowly and uniformly (2 K per 1016/cm2) for fluences less than 3×1016/cm2. Beginning at 3–4×1016/cm2, the superconducting transition broadened and dropped more quickly with fluence. The critical current density measured at 77 and 4.2 K changed roughly linearly with fluence. The microwaveT
c (as defined by the sharp transition inR
s as a function of temperature) resembled the low-frequency inductiveT
c measurement at low fluences but was depressed more strongly for large fluences. The residual surface resistance (6–10 m) was not affected for fluences up to 5×1016/cm2. We have interpreted the sudden and reproducible reduction in the microwaveT
c transition as a sensitive indicator of disruption in the copper-oxygen chain sublattice and compared the proton-induced change to that observed in oxygen gettering studies of bulk materials. 相似文献
5.
The evolution of the critical current density of Li-doped YBa2Cu3O7–x
polycrystalline samples submitted to neutron irradiation is investigated as function of magnetic field (0 B 6 T) temperature (5 T 85 K) and neutron fluence (0 9.98 × 1017 cm–2). At fluences lower than 1017 cm–2, a second peak in j
s
vs. B dependence is present (fish-tail effect). Its magnitude decreases with increasing the fluence. Above 1017 cm–2, the second peak of current density completely disappears; instead, the logarithmic susceptibility shows a second peak at a certain field B
infl. A dependence of B
infl on fluence is proposed. 相似文献
6.
Allen Kirkpatrick Daniel C. Harris Linda F. Johnson 《Journal of Materials Science》2001,36(9):2195-2201
Ion implantation with 11B+ or 28Si+ at 1000°C doubled the ring-on-ring flexure strength of c-plane sapphire disks tested at 300°C but had little effect on strength at 500 or 600°C. Disks were implanted on the tensile surface with 2 × 1017 B/cm2 (half at 40 keV and half at 160 keV) or 1 × 1017 Si/cm2 (80 keV). Sapphire implanted with 1 × 1018 B/cm2 had only half as much flexure strength at 300° or 500°C as sapphire implanted with 2 × 1017 B/cm2. Implantation with B, Si, N, Fe or Cr had no effect on the c-axis compressive strength of sapphire at 600°C. Boron ion implantation (2 × 1017 B/cm2, half at 40 keV and half at 160 keV) induced a compressive surface force per unit length of 1.9 × 102 N/m at 20° and 1.4 × 102 N/m at 600°C. The infrared emittance at 550–800° of B-implanted sapphire at a wavelength of 5 m increased by 10–15% over that of unimplanted sapphire. Infrared transmittance of sapphire implanted with B, Si or N at either 1000°C or 25°C is within 1–3% of that of unimplanted material at 3.3 m. Implantation with Fe or Cr at 25°C decreases the transmittance by 4–8% at 3.3 m, but implantation at 1000°C decreased transmittance by only 2–4% compared to unimplanted material. 相似文献
7.
V. Buscaglia M. Alvazzi Delfrate M. Leoni C. Bottino P. Nanni 《Journal of Materials Science》1996,31(7):1715-1724
The formation of Al2(1–x)Mg
x
Ti(1+x)O5 solid solutions from Al2O3-TiO2-MgAl2O4 powder mixtures of 1 m particle size and moderate purity has been studied at 1300°C for different final composition values: x=0 (pure Al2TiO5), 10–3, 10–2 and 10–1. Analysis of the kinetic data and microstructural observation indicates that MgAl2O4 affects the mechanism of Al2TiO5 formation by providing active nuclei for the growth of the new phase. These nuclei are probably constituted by Mg0.5AlTi1.5O5, i.e. the equimolar Al2TiO5-MgTi2O5 solid solution, and are formed by reaction between MgAl2O4 and TiO2 at temperatures above 1150 °C. As the value of x increases, the number of titanate particles per unit volume accordingly increases and the conversion of the original oxides is faster. At values of x10–2, the prevailing mechanism is the nucleation and growth of Al2TiO5 nodules for fractional conversion up to 0.8. Further conversion of the residual Al2O3 and TiO2 particles dispersed into the titanate nodules is slower and controlled by solid-state diffusion through Al2TiO5. At x=0.1, a large number of nucleation sites is present, and solid-state diffusion through Al2TiO5 becomes important even in the initial stage of reaction, as the diffusion distances are strongly reduced. The study of Al2TiO5 formation under non-isothermal conditions in the temperature range 1250–1550°C shows that reaction proceeds between 1300 and 1350 °C for x=0.01 and between 1250 and 1300 °C for x=0.1. Densification of the titanate becomes important at temperatures above 1300°C for x=0.1, but only above 1450 °C for x=0.01. 相似文献
8.
Diffusion over the temperature range 600-850 °C, electrodiffusion at 30 °C and effect of the Co substitution on crystalline structure and electrical characteristics of YBa2Cu3O7-y (YBaCuO) ceramic samples have been investigated by the energy dispersive X-ray fluorescence (EDX), X-ray diffraction (XRD), resistivity-temperature and current-voltage measurements. The temperature dependence of the cobalt diffusion coefficient (600-850 °C) via the grain boundaries has been described by the relation D=5.1×10-4exp(-1.12/kT). It is shown that the Co-doping of YBaCuO causes depression of the critical temperature and the critical current density. At the room temperature Co migrates in d.c. electric field preferentially in the form of positively charged ions with an effective charge q0.6- Electrodiffusion-stimulated orthorhombic-tetragonal transition, decrease in critical temperature and critical current density and change of the form of resistivity-temperature dependence are discovered. 相似文献
9.
Silicon oxynitride (SixOyNz) buried insulating layers were synthesized by dual implantation of nitrogen (14N+) and oxygen (16O+) ions sequentially into single crystal silicon in the ratio 1:1 at 150 keV to ion-fluences ranging from 1 × 1017 to 5 × 1017 cm−2. Heavy ion elastic recoil analysis (HI-ERDA) studies of as implanted samples show Gaussian like distributions of nitrogen and oxygen. After annealing at 800 °C, both the nitrogen and oxygen distributions appear as flat plateau like regions near projected range showing the formation of a continuous buried oxynitride layer. Micro-Raman study of as implanted samples shows a broad peak at 480 cm−1 for all fluences. It signifies a complete amorphization of silicon due to high fluence implantation. The annealing at 800 °C results in the reduction of the intensity of the broad peak observed at 480 cm−1 and also gives rise to an additional peak at 517 cm−1. It shows partial recrystallization of damaged silicon due to annealing. The X-ray rocking curves studies from high-resolution X-ray diffraction (HRXRD) of the samples implanted with different fluences have also further confirmed partial recrystallization of damaged silicon on annealing. 相似文献
10.
R. Tichý M. Odehnal V. Petříček S. Šafrata E. Pollert J. Kamarád J. Hejtmánek O. Smrčková D. Sýkorová 《Journal of Low Temperature Physics》1988,70(1-2):187-190
Quantum interference at liquid nitrogen temperature in a bulk sample of high-T
c superconductor YBa2Cu3O9–y is described. The SQUID quantization loop is formed at random inside the sintered sample as an internal percolation loop with a Josephson weak link. The estimated values of this multiply connected quantization loop are: the inductance of the loopL
SQ4×10–10 H, the critical currentI
c1×10–6 A, the area of the loopA1×10–8 m2, and the hysteresis parameter
L
1. In the flux-locked loop regime the field sensitivity of this liquid nitrogen SQUID with a random loop is 10–9 T/Hz1/2 and the resolution is 5×10–3 0/Hz1/2. 相似文献
11.
Thin films of Ni–Mn–Sn ferromagnetic shape memory alloy, grown on Si substrate by DC magnetron sputtering were bombarded by 450 keV Ar+ 4 ions at different fluences ranging from 1 × 1014 to 3 × 1016 ions/cm2 in order to investigate the effect of ion irradiation on characteristic transformation temperatures and thus on shape memory behavior. Temperature dependent resistivity measurements reveal the increase in martensitic transformation temperature (~ 100 K) upto a fluence of 1 × 1015 ions/cm2, above which shape memory behavior degrades and completely loses its behavior at 3 × 1016 ions/cm2, which is ascribed to the amorphization of Ni–Mn–Sn structure at a fluence of 3 × 1016 ions/cm2 as evidenced from X-ray diffraction pattern. The diffuse rings in the electron diffraction pattern also confirmed the amorphization of the film at highest fluence. The temperature dependent magnetization measurements also show the increase in martensitic transformation temperature upto a fluence of 1 × 1015 ions/cm2 in support of resistivity data. This work gives a possibility to acquire a better control on the properties of FSMA thin films using ion irradiation. 相似文献
12.
Low energy beta spectra are studied with sources encapsulated in a superconducting Sn absorber. An NTD germanium thermistor measures the temperature transient (5 msec) caused by individual beta decays, and the total energy not given to the neutrino is determined with a resolution of 0.5 keV (FWHM) and a threshold of 5 keV. The response function is determined from the mono-energetic electron capture and internal conversion source109
Cd, both separately and simultaneously with the beta spectrum. The endpoint of the unique first-forbidden decay107
Pd 107
Ag+e
–+
e
is found to be37.5±0.1 keV. High statistics results are compared to the unique first-forbidden shape and the atomic exchange correction. The latter is seen for the first time. Preliminary results of a search for heavy neutrino admixtures are0.15±0.33%. 相似文献
13.
Gergana I. Drandova Troy C. Messina Jae-Hyuk Choi Javier F. Hernandez John T. Markert 《Journal of Low Temperature Physics》2003,131(3-4):305-309
We report NMR lineshape, spin-lattice relaxation time T
1, and spin-spin relaxation time T
2 data at 17 MHz (8.07 T) for 89Y in the copper-oxide spin-chain compound Ca2+x
Y2–x
Cu5O10. For x=0, a broad, asymmetric line with width 90 kHz is observed for T=250–300 K. The spectra exhibit an appreciable average shift (H/H+0.7%) and sharpen at lower temperature, possibly due to increasing intrachain ferromagnetic correlations. T
1 and T
2 decrease with decreasing temperature. The Tl data imply a short correlation-time limit, with e=3–5×10–11 s. The T
2 data apparently include a contribution from dipolar interactions with copper nuclei. Relaxation time data for a doped (x=0.5) compound surprisingly show more rapid relaxation. 相似文献
14.
H. M. Naguib J. F. Singleton W. A. Grant G. Carter 《Journal of Materials Science》1973,8(11):1633-1640
The effect of 40 keV Kr ion bombardment of Al2O3 single crystals has been investigated using a Rutherford backscattering-channelling (RBC) technique. Curves of lattice disorder were found to be sigmoidal; the disorder increasing slowly up to a fluence of 1 × 1015 ions cm–2 and then accelerating to a saturation level at 1 × 1016 ions cm–2. These doses are about 100 times higher than comparable values found for elemental and III–V semiconductor compounds. The number of displaced atoms per incident ion estimated for an ion dose of 3 ×1014 ions cm–2 was found to be less than that calculated using Sigmund's equation. This difference is discussed in terms of defect recombination and re-ordering during bombardment. Measurements taken from the RBC random spectra before and after each bombardment have indicated that the stoichiometry of the alumina crystals did not alter even at the highest bombardment fluences used. 相似文献
15.
We have investigated interfacial chemistry in a 100 nm Ni on PTFE (polytetrafluoroethylene) bilayer system induced by 120 MeV Au ions with fluences varying from 1 × 1012 to 5 × 1013 ions/cm2. In-situ quadrupole mass analysis (QMA) shows emission of Fluorine (F) and different fluorocarbons (CxFy) such as CF, CF3, C2F3 etc. during irradiation. Electron spectroscopy for chemical analysis (ESCA) studies show that Ni reacts with chemically reactive species such as F−/F and CxFy ions or radicals emitted during irradiation forming NiF2 and metal-polymer complexes (-CFNi-). Rutherford backscattering spectrometry (RBS) was used to analyze the atomic transport at the interface and strong interface mixing is observed at the ion fluence 5 × 1013 ions/cm2. Atomic force microscopy (AFM) studies before and after irradiation show that surface roughness is increased from 6.9 to 12.4 nm with increasing fluence. Observed results have been explained on the basis of the chemical reactions taking place within molten ion tracks in the polymer and hot zones around the ion paths created in the Ni film. The studies show that swift heavy ion irradiation introduces strong chemical alteration in the system and induces chemical reactions within the ion track, which enhance ion beam mixing in Ni-PTFE bilayer systems. 相似文献
16.
The co-evaporated SiO
x
-Ge system was studied. Thin-film MIM sandwich structures were deposited by vacuum evaporation at a pressure of 10–4 Pa and were measured at a pressure of 10–3 Pa. The conductivity at low temperature and under d.c. fields has been found to be governed by a combination of an electronic hopping process and free-band conduction. At fields greater than 2 × 106 V m–1, it is concluded that the conduction process is governed by the Poole-Frenkel effect. Comparison with earlier results on SiO
x
-GeO2 films showed small differences in activation energy for conduction for samples of broadly similar overall composition. 相似文献
17.
Z. S. Peng C. R. Wan C. Y. Jiang Z. Q. Hua B. C. Yang X. H. Wang B. Yin Z. X. Zhao J. M. Hao 《Journal of Superconductivity》1996,9(5):519-522
Experimental results of research on the influence of deposition temperature (T
s) on crystal structure and superconductivity of Y1–x
HoxBa2Cu3O7 – (YHBCO) films deposited by dcmagnetron sputtering are reported. X-ray diffraction analysis showed that the films grew with preferential orientation of thec-axis normal to the substrate surface in the range of temperature 750–820°C. The single-crystal structure of the YHBCO films grown epitaxially at the optimal substrate temperatures of 820, 800, 760, and 750°C, respectively, have been established by rocking curves, -scan, and electron channeling pattern (ECP). Typical values of the critical current density (A · cm–2) at 77 K and 0.1 T field are 2.1×105, 4×105, 6.2×105, and 3.1×105 for thex=0, 0.2, 0.4, 0.7 films respectively, measured by a Quantum Design magnetrometer (Hc). 相似文献
18.
Paul F. Becher 《Journal of Materials Science》1986,21(1):297-300
The room temperature slow crack growth resistance in air ( 50% relative humidity) and in water for large cracks in MgO-partially stabilized zircoba (PSZ) improves with increase in critical fracture toughness,K
lc. Ageing the as-fired PSZ at 1400° C for 8 h results in decreasing Klc from 8.5 MPa m1/2 to 6 M Pa M1/2. The ageing treatment also promotes the growth of eutectoid decomposition products on grain boundaries that is accompanied by a decrease in the dependence (A the change in Region I crack velocity with a change in the applied stress intensity. Calculated times to failures are markedly decreased in the aged as compared to the as-fired PSZ ceramic. 相似文献
19.
Infrared and structural properties of Y1–x
Nd
x
Ba2Cu3O7– (0 x 1) were investigated using infrared absorption spectroscopy and X-ray powder diffraction. The unit cell parameters of the samples were defined using X-ray diffraction data. The resistance measurements showed that the samples revealed superconductivity in the temperature range of 80–100 K. It was observed that by the substitution of Nd to Y in YBa2Cu3O7 – IR band at 573 cm–1 that is assigned as Cu–O axial antisymmetric stretching mode shifts to 533 cm–1 while the band at 620 cm–1 that is due to Cu–O symmetric stretching mode in YBa2Cu3O7– shifts to 588 cm–1. 相似文献
20.
The in-plane resistivity of stage 1 and stage 2 AsF5-graphite intercalation compounds was measured using a contactless r.f. eddy current technique from 1.6 to 290 K. The magnetoresistance of a stage 1 compound was similarly measured from 4.2 K to 290 K. The low temperature stage 2 resistivity data show a well-defined intermediate T
2 region in addition to the usual T high temperature region, in qualitative agreement with the Kukkonen theory and indicative of a small, elongated cylindrical Fermi surface. Stage 2 resistivity data also show, for the first time in a graphite-acceptor compound, an apparent low temperature phase transition at 21 K. Magnetoresistance data were used to determine a stage 1 carrier concentration of 9×1020 holes cm–3. Resistive anomalies were observed at 200 K and 220 K for stage 1 and stage 2 compounds, respectively. 相似文献