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11.
R. Germar W. Dürr J. W. Krewer D. Pescia W. Gudat 《Applied Physics A: Materials Science & Processing》1988,47(4):393-398
We have used plots of the Auger amplitudes versus deposition time to investigate the growth mode of 3d-transition metals on
noble metal (100) surfaces. The systems considered are Fe/Cu(100), Fe/Au(100), Co/Cu(100), and Cr/Ag(100). We find that: 1.
The Auger plots consist of a succession of straight lines of constant length with sharp breaks in between, i.e. the growth
mode is essentially layer-by-layer. 2. From the experimental data points a slight rounding off in the vicinity of the break
points cannot be excluded, although a numerical analysis shows that the deviation from perfect layer-by-layer growth is less
than 10% of a monolayer for all systems considered. 相似文献
12.
K. Sadhana 《Journal of magnetism and magnetic materials》2010,322(23):3729-3736
The nanocrystalline Ni0.53Cu0.12Zn0.35Fe1.88O4 and BaTiO3 powders were prepared using Microwave-Hydrothermal (M-H) method at 160 °C/45 min. The as synthesized powders were characterized using the X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). The size of the powders that were synthesized using M-H system was found to be ∼30 and ∼50 nm for ferrite phase and ferroelectric phases, respectively. The powders were densified using microwave sintering method at 900 °C/30 min. The ferrite and ferroelectric phases were observed from XRD and morphology of the composites was observed with the Scanning Electron Microscope (SEM).The magnetic hysteresis loops were recorded using the Vibrating Sample Magnetometer (VSM).The frequency dependence of real (μ′) and imaginary (μ″) parts of permeability was measured in the range of 1 MHz-1.8 GHz. The permeability decreases with an increase of BaTiO3 content at 1 MHz. The transition temperature (TC) of ferrite was found to be 245 °C. The TC of composite materials decreases with an increase in BaTiO3 content. 相似文献
13.
Marina Davydova Alexander Kromka Oleg Babchenko Karel Hruska 《Applied Surface Science》2010,256(18):5602-1312
Diamond nanorods were fabricated for a sensing device by utilizing reactive ion etching in CF4/O2 radio frequency plasma. The length of the nanorods has been controlled by the ion etching time. The obtained morphologies were investigated by scanning electron microscopy. The gas sensing properties of the H-terminated diamond-based sensor structures are indicating that we have achieved high sensitivity to detect phosgene gas. Also, our sensor exhibited good selectivity between humid air and phosgene gas if the measurement is conducted at elevated temperatures, such as 140 °C. Furthermore, such sensor response rating could reach as high value as 4344 for the phosgene gas, which was evaluated for the sample consisting of the longest nanorods (up to 200 nm). 相似文献
14.
Bunch lengthening phenomenon is resulted from one of the most severe single bunch instabilities in storage rings. We develop a new code to calculate the single bunch length and energy spread in storage rings using FORTRAN. In this code, wake field is calculated using an analytical formula, which is different from the previous ones. The bunch length and energy spread under different bunch currents are calculated for BEPCII by using this code, and the tracking results are in good agreement with those from other codes. The calculated energy spread clearly shows that the longitudinal microwave instability threshold is around 65 mA for BEPCII storage ring. 相似文献
15.
Dongjiang Wang Yongchang Liu Yajing Han Yanhua Zhang Zhiming Gao 《Applied Physics A: Materials Science & Processing》2008,92(3):703-707
Though much progress has been made on the phase transformation kinetics model, little attention has been paid to the incubation
reaction before the transformation initiates. In this study, the kinetics characteristics of the incubation time during isothermal
reaction and the onset temperature during isochronal one are indicated. A model is established with the consideration of the
incubation time corresponding to its annealing temperature during the isothermal case and the onset temperature corresponding
to its heating rate during the isochronal case, from which a correlation between the incubation time and the onset temperature
can be drawn. Finally, the proposed model has been applied well to the crystallization of Mg65Cu25Y10 amorphous alloy. 相似文献
16.
Y. Liu T. P. Chen M. Yang Z. H. Cen X. B. Chen Y. B. Li S. Fung 《Applied Physics A: Materials Science & Processing》2009,95(3):753-756
Electroluminescence (EL) from Al-rich AlN thin films grown on p-type Si substrate by radio frequency (RF) magnetron sputtering
has been observed at room temperature. The light-emitting structure based on the thin films can be driven by an electrical
pulse as short as 10−5 s. No obvious change in the light emission intensity was observed after 106 pulse cycles. It has been found that the light emission intensity increases with the Al concentration. It is shown that the
phenomenon is due to the enhancement of the percolative conduction via the Al nanocrystals distributed in the AlN matrix as
a result of the increase in Al concentration. 相似文献
17.
Inter-particle spin-polarized tunneling was measured in an organically capped magnetite nanocrystal (NC) array deposited between 30 nm spaced gold electrodes. Magnetoresistance (MR) measurements performed around the blocking temperature (Tb) of the magnetic moments of the particles in the array, which was relatively high (220 K), yielded negative MR values of the order of 10-25% under moderate magnetic fields of several kOe. The field dependence of the MR followed closely the square of the film's magnetization and its voltage dependence indicated maximal spin polarization around the Fermi level. These findings suggested that the measured MR is the result of spin-polarized tunneling between individual magnetite NCs acting as superparamagnetic spin polarizers. 相似文献
18.
19.
Xiaobin WuZhiming Yu Xiaolong YouMengkun Tian Yilun Gong 《Applied Surface Science》2012,258(6):2117-2120
A periodically magnetic field (PMF) was used in a hot-filament chemical vapor deposited (HFCVD) for diamond growth on the rhenium substrate. The morphology, band structures and crystalline structure of the film were analyzed by the scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffractometer (XRD), respectively. The results show that the thickness of the diamond film is about 2900 nm by 4 h deposition with magnetic field-assisted. There is no interlayer between diamond film and the rhenium substrate. The result shows that the turn on voltage of the sample is enhanced from 3.3 to 2.6 V/μm with the PMF. Also the total emission current density at 6.2 V/μm increased from 6.3 to 21.5 μA/cm2. 相似文献
20.
G. Bour A. Reinholdt A. Stepanov C. Keutgen U. Kreibig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):219-223
We studied the effect of hydrogen in yttrium nanoparticles on a quartz substrate, using optical spectroscopy and electrical
resistance measurements. Pulsed laser deposition is used to obtain the Y clusters in an UHV environment. We show, that these
clusters are highly sensitive to monoatomic H1 produced from ambient hydrogen gas pressures, ranging from 10-5 to 50 mbar with our experimental arrangement. The changes of optical and electrical properties due to the chemical reaction
within the particles are sufficient to consider this material as a possible sensor for low concentrations of hydrogen.
Received 29 November 2000 相似文献