共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Matsushita W. Sakai K. Nakajima M. Suzuki K. Kimura A. Agarwal H.-J. Gossmann M. Ameen 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):230-233
The damage distributions induced by ultra low energy ion implantation (5 keV Si+) in both strained-Si/Si0.8Ge0.2 and normal Si are measured using high-resolution RBS/channeling with a depth resolution better than 1 nm. Ion implantation was performed at room temperature over the fluence range from 2 × 1013 to 1 × 1015 ions/cm2. Our HRBS results show that the radiation damage induced in the strained Si is slightly larger than that in the normal Si at fluences from 1 × 1014 to 4 × 1014 ions/cm2 while the amorphous width is almost the same in both strained and normal Si. 相似文献
2.
Vassili Bandourko Naoki Umeda Oleg Plaksin Naoki Kishimoto 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):471-475
Silica glass was implanted with negative 60 keV Cu ions at an ion flux from 5 to 75 μA/cm2 up to a fluence of 1 × 1017 ions/cm2 at initial sample temperatures of 300, 573 and 773 K. Spectra of ion-induced photon emission (IIPE) were collected in situ in the range from 250 to 850 nm. Optical absorption spectra of implanted specimens were ex situ measured in the range from 190 to 2500 nm.
IIPE spectra showed a broad band centered around 560 nm (2.2 eV) that was assigned to Cu+ solutes. The band appeared at the onset of irradiation, increased in intensity up to a fluence of about 5 × 1015 ions/cm2 and then gradually decreased indicating three stage of the ion beam synthesis of nanoclusters: accumulation of implants, nucleation and growth nanoclusters. The IIPE intensity normalized on the ion flux is independent on the ion flux below 20 μA/cm2at higher fluences. The intensity of the band increased with increasing samples temperature, when optical absorption spectra reveal the increase of Cu nanoparticles size. 相似文献
3.
X. Xiang X.T. Zu S. Zhu C.F. Zhang Z.G. Wang L.M. Wang R.C. Ewing 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):382-385
Xe+ ion implantation with 200 keV was completed at room temperature up to a fluence of 1 × 1017 ion/cm2 in yttria-stabilized zirconia (YSZ) single crystals. Optical absorption and X-ray photoelectron spectroscopy (XPS) were used to characterize the changes of optical properties and charge state in the as-implanted and annealed crystals. A broad absorption band centered at 522 or 497 nm was observed in the optical absorption spectra of samples implanted with fluences of 1 × 1016 ion/cm2 and 1 × 1017 ion/cm2, respectively. These two absorption bands both disappeared due to recombination of color centers after annealing at 250 °C. XPS measurements showed two Gaussian components of O1s spectrum assigned to Zr–O and Y–O, respectively, in YSZ single crystals. After ion implantation, these two peaks merged into a single peak with the increasing etching depth. However, this single peak split into two Gaussian components again after annealing at 250 °C. The concentration of Xe decreased drastically after annealing at 900 °C. And the XPS measurement barely detected the Xe. There was no change in the photoluminescence of YSZ single crystals with a fluence of 1 × 1017 ion/cm2 after annealing up to 900 °C. 相似文献
4.
Xiang Liu Tsuyoshi Yamada Yuji Yamauchi Yuko Hirohata Tomoaki Hino Nobuaki Noda 《Fusion Engineering and Design》2004,70(4):425-334
Helium irradiation experiments of V–4Ti alloy were conducted in an ECR ion irradiation apparatus by using helium ions with energy of 5 keV. The ion fluence was in the range from 1 × 1017 He/cm2 to 8 × 1017 He/cm2. After the helium ion irradiation, the helium retention was examined by using a technique of thermal desorption spectroscopy (TDS). After the irradiation, the blisters with a size of about 0.1 μm were observed at the surface, and the blister density increased with the ion fluence. Two desorption peaks were observed at approximately 500 and 1200 K in the thermal desorption spectrum. When the ion fluence was low, the retained helium desorbed mainly at the higher temperature regime. As increase of the ion fluence, the desorption at the lower temperature peak increased and the retained amount of helium saturated. The saturated amount was approximately 2.5 × 1017 He/cm2. This value was comparable with those of the other plasma facing materials such as graphite. 相似文献
5.
T. Onchi K. Dohi N. Soneda Marta Navas M.L. Castao 《Journal of Nuclear Materials》2005,340(2-3):219-236
Thermally sensitized 304 stainless steels, irradiated up to 1.2 × 1021 n/cm2 (E > 1 MeV), were slow-strain-rate-tensile tested in 290 °C water containing 0.2 ppm dissolved oxygen (DO), followed by scanning and transmission electron microscopic examinations, to study mechanism of irradiation-assisted-stress-corrosion-crack (IASCC) initiation. Intergranular (IG) cracking behaviors changed at a border fluence (around 1 × 1020 n/cm2), above which deformation twinning were predominant and deformation localization occurred earlier with increasing fluence. The crack initiation sites tended to link to the deformation bands, indicating that the crack initiation may be brought about by the deformation bands interacted with grain boundaries. Thus the border fluence is equivalent to the IASCC threshold fluence for the sensitized material, although the terminology of IASCC is originally given to the non-sensitized materials without microstructural definition. The IASCC threshold fluence was found to change with irradiation conditions. Changes in IASCC susceptibility and IASCC threshold fluence with fluence and DO were further discussed. 相似文献
6.
Janez Megusar 《Journal of Nuclear Materials》1996,230(3):233-241
Structure and chemistry of S2-glass fiber-epoxy composite to fast-neutron and gamma irradiation at 4.2 K have been studied. Fast-neutron fluence ranged from 0.9 × 1022 to 1 × 1023 n/m2. At the neutron fluence of 3.1 × 1022 n/m2, ordering of the amorphous S2-glass structure intervened. Ordering was followed by partial crystallization at the neutron fluence of 1 × 1023 n/m2. Although the epoxy matrix retained its amorphous structure, reactor irradiation induced crosslink formation and hydrogen evolution. These processes became significant at neutron fluences equal to or higher than 1.8 × 1022 n/m2. No evidence has been found for hydrogen bubble or void nucleation at the glass-epoxy interface at the neutron fluence of 3.1 × 1022 n/m2. Futhermore, sharp compositional changes measured at the glass-epoxy interface preclude an extended irradiation-induced atom mixing at this neutron fluence. 相似文献
7.
Andrej Zeman Luigi Debarberis Ludovít Kup
a Beatriz Acosta Milo Kytka Jarmila Degmov 《Journal of Nuclear Materials》2007,360(3):272-281
The influence of different microstructural processes on the degradation due to radiation embrittlement has studied by positron annihilation and Mössbauer spectroscopy. The materials studied consisted of WWER-440 base (15Kh2MFA) and weld (10KhMFT) RPV steels which were neutron-irradiated at fluence levels of 0.78 × 1024 m−2, 1.47 × 1024 m−2 and 2.54 × 1024 m−2; WWER-1000 base (15Kh2NMFAA) and weld (12Kh2N2MAA) irradiated at a fluence level 1.12 × 1024 m−2; three different model alloys implanted with protons at two dose levels (up to 0.026 dpa), finally the base metal of WWER-1000 (15Kh2NMFAA) was thermally treated with the intention to simulate the P-segregation process. It has been shown possible to correlate the values of parameters obtained by such techniques and data of mechanical testing (ductile-to-brittle transition temperature and upper shelf energy). 相似文献
8.
M. Miyakawa H. Kamioka M. Hirano T. Kamiya H. Hosono 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):368-371
Au+ ion implantation with fluences from 1 × 1014 to 3 × 1016 cm−2 into 12CaO · 7Al2O3 (C12A7) single crystals was carried out at a sample temperature of 600 °C. The implanted sample with the fluence of 1 × 1015 cm−2 exhibited photoluminescence (PL) bands peaking at 3.1 and 2.3 eV at 150 K when excited by He–Cd laser (325 nm). This was the first observation of PL from C12A7. These two PL bands are possibly due to intra-ionic transitions of an Au− ion having the electronic configuration of 6s2, judged from their similarities to those reported on Au− ions in alkali halides. However, when the concentration of the implanted Au ions exceeded the theoretical maximum value of anions encaged in C12A7 (2.3 × 1021 cm−3), surface plasmon absorption appeared in the optical absorption spectrum, suggesting Au colloids were formed at such high fluences. These observations indicate that negative gold ions are formed in the cages of C12A7 by the Au+ implantation if an appropriate fluence is chosen. 相似文献
9.
Y. Takeda O.A. Plaksin J. Lu K. Kono N. Kishimoto 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):372-376
Optical nonlinearity and dispersion were studied for Cu nanoparticle composite. Negative Cu− ions with 60 keV were applied for implanting into SrTiO3 at a flux of 10 μA/cm2 up to a total fluence of 1 × 1017 ions/cm2. The steady-state optical spectrum of Cu-implanted SrTiO3 showed a surface plasmon resonance resulting from the formation of nanoparticles. Transient transmission and reflection were measured by the pump–probe method with a femtosecond laser system. Optical nonlinearity originated from Cu:SrTiO3 nanoparticle composite and from SrTiO3 matrix overlap, in measured transient spectra. The nonlinear component of Cu:SrTiO3 composite was extracted from the transient spectra with the difference of time response. Nonlinear dielectric coefficient and dispersion around the surface plasmon resonance were derived from extracted transient spectra. The dispersion was compared with a local electric field factor. 相似文献
10.
Yang Tan Feng Chen Lei Wang Yang Jiao 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,260(2):567-570
We report on the optical planar waveguides in Nd:YLiF4 laser crystals fabricated by 6.0 MeV C3+ ion implantation at doses of 1 × 1015 or 2.5 × 1015 ions/cm2, respectively. The refractive index profiles, which are reconstructed according to the measured dark mode spectroscopy, show that the ordinary index had a positive change in the surface region, forming non-leaky waveguide structures. The extraordinary index is with a typical barrier-shaped distribution, which may be mainly due to the nuclear energy deposition of the incident ions into the substrate. In order to investigate the thermal stability of the waveguides, the samples are annealed at temperature of 200–300 °C in air. The results show that waveguide produced by higher-dose carbon implantation remains relatively stable with post-irradiation annealing treatment at 200 °C in air. 相似文献
11.
G.G. Ross R. Smirani V. Levitcharsky Y.Q. Wang G. Veilleux R.G. Saint-Jacques 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):198-202
Si nanocrystals (Si-nc) embedded in a SiO2 layer have been characterized by means of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). For local Si concentration in excess 8 × 1021 Si+/cm3, the size of the Si-nc was found to be 3 nm and comparatively homogeneous throughout the whole implanted layer. For local Si concentration in excess of 2.4 × 1022 Si+/cm3, the Si-nc diameter ranges from 2 to 12 nm in the sample, the Si-nc in the middle region of the implanted layer being bigger than those near the surface and the bottom of the layer. Also, Si-nc are visible deeper than the implanted depth. Characterization by XPS shows that a large quantity of oxygen was depleted from the first 25 nm in this sample (also visible on TEM image) and most of the SiO2 bonds have been replaced by Si–O bonds. Experimental and simulation results suggest that a local Si concentration in excess of 3 × 1021 Si/cm3 is required for the production of Si-nc. 相似文献
12.
We summarize the diametral creep results obtained in the MR reactor of the Kurchatov Institute of Atomic Energy on zirconium-2.5 wt% niobium pressure tubes of the type used in RBMK-1000 power reactors. The experiments that lasted up to 30 000 h cover a temperature range of 270 to 350°C, neutron fluxes between 0.6 and 4.0 ×1013 n/cm2 · s (E > 1 MeV) and stresses of up to 16 kgf/mm2. Diametral strains of up to 4.8% have been measured. In-reactor creep results have been analyzed in terms of thermal and irradiation creep components assuming them to be additive. The thermal creep rate is given by a relationship of the type εth = A1 exp [(A2 + A 3σt) T] and the irradiation component by εrad = A4σtø(T − A5), where T = temperature, σt = hoop stress, ø = neutron flux and a1 to A5 are constants. Irradiation growth experiments carried out at 280° C on specimens machined from pressure tubes showed a non-linear dependence of growth strain on neutron fluence up to neutron fluences of 5 × 1020 n/cm2. The significance of these results to the elongation of RBMK reactor pressure tubes is discussed. 相似文献
13.
Rosenbluth M. Bloss W.L. Yamada W.E. Janousek B.K. 《IEEE transactions on nuclear science》1991,38(1):20-24
A systematic investigation of the effects of high-energy neutrons on GaAs metal-semiconductor field-effect transistors (MESFETs) and buffered FET logic (BFL) gates has been carried out. Discrete transistors, inverters, and ring oscillators were characterized and modeled as a function of neutron fluence. Measurements were made of the threshold voltage shifts, the transconductance degradation, and saturation current degradation of GaAs depletion mode MESFETs, which comprise the BFL logic gates, irradiated with neutron fluences ranging from 5×1013 n/cm2 to 2×1015 n/cm2 (for particle energies above 10 keV). The threshold voltage was found to shift positively by 0.45 V, the transconductance decreased to 3%, and the saturation current to 1% of their unirradiated values at the highest neutron fluence (2×1015 n/cm2). The BFL inverter characteristics were measured and successfully simulated with SPICE using device parameters extracted from the neutron-damaged FETs. Ring oscillator measurements were made to determine the effects of high-energy neutrons on the frequency performance of BFL circuits. The ring oscillator frequency decreased to 9% of its unirradiated value at the highest neutron fluence 相似文献
14.
The release of tritium from irradiated boron carbide in a pure Ar atmosphere was investigated between 500 and 900°C. The sintered B4C samples with densities between 75 and 95% of the theoretical density were irradiated with reactor neutrons with total neutron doses up to 5 × 1020/cm2. Effective diffusion coefficients, Deff, were derived from the release data using the model “diffusion out of a sphere”. Deff decreases by about 3 orders of magnitude with increasing total neutron dose, levels off at about 1018n/cm2 and increases at very high doses ( > 1020 n/cm2). The decrease in the tritium mobility is attributed to the radiation defects formed in the B4C. The activation energy of 210 ± 30 kJ/mol for the tritium diffusion in the irradiated B4C is much higher than the value found for unirradiated material. Deff depends also very strongly on the density of the sintered material. 相似文献
15.
Michel Beauvy Chrystelle Dalmasso Philibert Iacconi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):137-141
Actinide oxides have been used as nuclear fuels in the majority of power reactors working in the world and actinide nitrides are under investigation for the fuels of the future fast neutron fission reactors developed in Forum Generation IV. Radiation damage in actinide oxides UO2, (U0.92Ce0.08)O2, and actinide nitride UN has been characterized after irradiation with swift heavy ions. Fluences up to 3 × 1013 ions/cm2 of heavy ions (Kr 740 Mev, Cd 1 GeV) available at the CIRIL/GANIL facility were used to simulate irradiation in reactors by fission products and by neutrons. The macroscopic effects of irradiation remains very weak compared with those seen in other ceramic oxides irradiated in the same conditions: practically no swelling can be measured and no change in colour can be observed on the irradiated part of a polished face of sintered disks. The point defects in irradiated actinide compounds have been characterized by optical absorption spectroscopy in the UV–Vis–NIR wavelength range. The absorption spectra before and after irradiation are compared, and unexpected stability of optical properties during irradiation is shown. This result confirms the low rate of formation of point defects in actinide oxides and actinide nitrides under irradiation. Actinide oxides and nitrides studied are >40% ionic, and oxidation state of the actinides seems to be stable during irradiation. The small amount of point defects produced by radiation (<1016 cm−2) has been identified from differences between the absorption spectrum before irradiation and the one after irradiation: point defects in oxygen or nitrogen lattices can be observed respectively in oxides and nitrides (F centres), and small amounts of U5+ would be present in all compounds. 相似文献
16.
U.S. Sias L. Amaral M. Behar H. Boudinov E.C. Moreira 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):178-182
In the present work we have studied the photoluminescence (PL) behavior from Si nanocrystals (NCs) as a function of the excitation power density and annealing time. The NCs were produced in a SiO2 matrix by Si implantations from room temperature (RT) up to 700 °C, followed by post-annealing in N2 atmosphere at high temperature. With this aim we have changed the excitation power density (from 2 × 10−3 W/cm2 up to 15 W/cm2) and the annealing time (from 10 min up to 15 h). The strong PL signal, which at 15 W/cm2 is composed by a single-peak structure (650–1000 nm) centered at around 780 nm, expands up to 1200 nm showing a two-peak structure when measured at 20 × 10−3 W/cm2. The peak structure located at the short wavelength side is kept at 780 nm, while the second peak, starting at around 900 nm, redshifts and increases its intensity with the implantation temperature and annealing time. The effect of the annealing time on the PL spectra behavior measured at low excitation power agrees by the first time with the Si NC growth according to quantum confinement effects. 相似文献
17.
Tetsuo Matsumoto 《Progress in Nuclear Energy》2000,37(1-4):327-332
Neutron beam designs were studied for TRIGA reactor with a view to generating thermal, epithermal and fast neutron beams for both medical neutron capture therapy (NCT) and industrial neutron radiography (NR). The beams are delivered from thermal and thermalizing columns, and also horizontal beam hole. Several prospective neutron filters (high-density graphite (G), bismuth (Bi), single-crystal silicon (Si), aluminum (Al), aluminum oxide (Al2O3), aluminum fluoride (AlF3) and lead fluoride (PbF2)) were examined for obtaining sufficiently intense neutron beam for various applications. Monte Carlo calculations indicated that with a suitable neutron filter arrangement, thermal and epithermal neutron beams attaining 2×109 and 7×108 n cm−2S−1, respectively, could be obtainable from thermal and thermalizing columns with the reactor operating at 100 kW. These neutron beams could be adopted for boron neutron capture therapy. Compared with these columns, horizontal beam port would deliver neutron fluxes of 10−2 10−3 lower intensity, but produced thermal and neutron beams would be adequate for different application of nondestructive inspection by neutron radiography. 相似文献
18.
Yunlong Cui Senhao Lin Tingwen Rong Jingrong Bao Jianguo Zhang 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1995,100(4):502-504
Pristine C60 films sublimed onto sheet mica were implanted with 20 keV K+ ions and I+ ions at doses of 1.0 × 1016/cm2, 3.0 × 1016/cm2 and 5.0 × 1016/cm2, and with 20 keV Ar+ ions at a dose of 5.0 × 1016/cm2. The distributions of dopants were studied using Rutherford backscattering spectrometry (RBS). The temperature dependence of sheet resistivity of the films was investigated applying a four-probe system. It was proposed that the conductivity enhancement of K+ implanted C60 films was due to the implanted ions in the films, while for I+ implanted C60 films, both implanted I+ ions and irradiation effects of the ions contributed to the enhancement of conductivity. 相似文献
19.
D. Spemann K. Schindler P. Esquinazi M. Diaconu H. Schmidt R. Hhne A. Setzer T. Butz 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):303-308
In this study, ferromagnetic microstructures in highly oriented pyrolytic graphite and superparamagnetic spots in polyimide foils were created by 2.25 MeV proton microbeam irradiation and characterized using atomic and magnetic force microscopy. For this purpose, graphite samples were irradiated with cross-like patterns of 15 μm × 15 μm size using ion fluences in the range of (0.003–2.5) × 1018 cm−2. The irradiated crosses showed strong magnetic signals and a complex domain structure in the magnetic images depending on the geometrical dimensions of the crosses. Furthermore, polyimide foils were irradiated with microspots and fluences in the range of (0.016–3.1) × 1019 cm−2. Magnetic force microscopy shows very strong phase shifts in these irradiated areas. 相似文献
20.
D. K. Sarkar S. Dhara K. G. M. Nair S. Chowdhury 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2000,170(3-4):413-418
In the present study, a 500 Å thin Ag film was deposited by thermal evaporation on 5% HF etched Si(1 1 1) substrate at a chamber pressure of 8×10−6 mbar. The films were irradiated with 100 keV Ar+ ions at room temperature (RT) and at elevated temperatures to a fluence of 1×1016 cm−2 at a flux of 5.55×1012 ions/cm2/s. Surface morphology of the Ar ion-irradiated Ag/Si(1 1 1) system was investigated using scanning electron microscopy (SEM). A percolation network pattern was observed when the film was irradiated at 200°C and 400°C. The fractal dimension of the percolated pattern was higher in the sample irradiated at 400°C compared to the one irradiated at 200°C. The percolation network is still observed in the film thermally annealed at 600°C with and without prior ion irradiation. The fractal dimension of the percolated pattern in the sample annealed at 600°C was lower than in the sample post-annealed (irradiated and then annealed) at 600°C. All these observations are explained in terms of self-diffusion of Ag atoms on the Si(1 1 1) substrate, inter-diffusion of Ag and Si and phase formations in Ag and Si due to Ar ion irradiation. 相似文献