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971.
Far-field divergence of a vectorial plane wave diffracted by a circular aperture from the vectorial structure 下载免费PDF全文
Based on the vectorial structure of an electromagnetic wave, the analytical and concise expressions for the TE and TM terms of a vectorial plane wave diffracted by a circular aperture are derived in the far-field. The expressions of the energy flux distributions of the TE term, the TM term and the diffracted plane wave are also presented. The ratios of the power of the TE and TM terms to that of the diffracted plane wave are examined in the far-field. In addition, the far-field divergence angles of the TE term, the TM term and the diffracted plane wave, which are related to the energy flux distribution, are investigated. The different energy flux distributions of the TE and TM terms result in the discrepancy of their divergence angles. The influences of the linearly polarized angle and the radius of the circular aperture on the far-field divergence angles of the TE term, the TM term and the diffracted plane wave are discussed in detail. This research may promote the recognition of the optical propagation through a circular aperture.vspace1mm 相似文献
972.
Z.H. Zhang X.L. Zhong H. Liao F. Wang J.B. Wang Y.C. Zhou 《Applied Surface Science》2011,257(17):7461-7465
In the present work, X-ray photoelectron spectroscopy (XPS) was used to investigate the composition depth profiles of Bi3.15Nd0.85Ti3O12 (BNT) ferroelectric thin film, which was prepared on Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates by chemical solution deposition (CSD). It is shown that there are three distinct regions formed in BNT film, which are surface layer, bulk film and interface layer. The surface of film is found to consist of one outermost Bi-rich region. High resolution spectra of the O 1s peak in the surface can be decomposed into two components of metallic oxide oxygen and surface adsorbed oxygen. The distribution of component elements is nearly uniform within the bulk film. In the bulk film, high resolution XPS spectra of O 1s, Bi 4f, Nd 3d, Ti 2p are in agreement with the element chemical states of the BNT system. The interfacial layer is formed through the interdiffusion between the BNT film and Pt electrode. In addition, the Ar+-ion sputtering changes lots of Bi3+ ions into Bi0 due to weak Bi-O bond and high etching energy. 相似文献
973.
Sebastián Feliu Jr. C. MaffiotteA. Samaniego Juan Carlos GalvánVioleta Barranco 《Applied Surface Science》2011,257(20):8558-8568
The purpose of this study has been to advance in knowledge of the chemical composition, structure and thickness of the thin native oxide film formed spontaneously in contact with the laboratory atmosphere on the surface of freshly polished commercial AZ31 and AZ61 alloys with a view to furthering the understanding of protection mechanisms. For comparative purposes, and to more fully describe the behaviour of the native oxide film, the external oxide films formed as a result of the manufacturing process (as-received condition) have been characterised. The technique applied in this research to study the thin oxide films (thickness of just a few nanometres) present on the surface of the alloys has basically been XPS (X-ray photoelectron spectroscopy) in combination with ion sputtering. Corrosion properties of the alloys were studied in 0.6 M NaCl by measuring charge transfer resistance values, which are deduced from EIS (electrochemical impedance spectroscopy) measurements after 1 h of exposure. Alloy AZ61 generally showed better corrosion resistance than AZ31, and the freshly polished alloys showed better corrosion resistance than the alloys in as-received condition. This is attributed to a combination of (1) higher thickness of the native oxide film on the AZ61 alloy and (2) greater uniformity of the oxide film in the polished condition. The formation of an additional oxide layer composed by a mixture of spinel (MgAl2O4) and MgO seems to diminish the protective properties of the passive layer on the surface of the alloys in as-received condition. 相似文献
974.
Nanoporous ZnO/SiO2 bilayer coatings were prepared on the surface of glass substrates via sol-gel dip-coating process. The structural, morphological and optical properties of the coatings were characterized. The refractive indices of ZnO layer and SiO2 layer are 1.34 and 1.21 at 550 nm, respectively. The transmittance and reflectance spectra of the coatings were investigated and the broadband antireflection performance of the bilayer structure was determined over the solar spectrum. The solar transmittances in the range of 300-1200 nm and 1200-2500 nm are increased by 6.5% and 6.2%, respectively. The improvement of transmittance is attributed to the destructive interference of light reflected from interfaces between the different refractive-index layers with an optimized thickness. Such antireflection coatings of ZnO/SiO2 provide a promising route for solar energy applications. 相似文献
975.
Jingkai YangWenchang Liu Lizhong DongYuanxun Li Chuan LiHongli Zhao 《Applied Surface Science》2011,257(24):10499-10502
Fluorine-doped tin oxide films (SnO2:F, FTO) were deposited by atmosphere pressure chemical vapor deposition (APCVD) on Na-Ca-Si glass coated with a diffusion barrier layer of SiOxCy. The effects of post-heating time at 700 °C on the structural and electrical properties of SnO2:F films were investigated. The results showed that SnO2:F films were polycrystalline with tetragonal SnO2 structure, SnO phase was present in SnO2 film, and abnormal grain growth was observed. The element distribution in the film depth was measured with X-ray photoelectron spectroscopy (XPS) and revealed that when the heating time increased from 202 s to 262 s, the oxygen content in the surface increased from 78.63% to 83.38%. The resistivity increased from 3.13 × 10−4 for as-deposited films to 4.73 × 10−4 Ω cm when post-heated for 262 s. Hall mobility is limited by the ionized impurity scattering rather than the grain boundary scattering. 相似文献
976.
Chih-Chieh LoChun-Chao Huang Chien-Min LiuChih Chen Chang-Yang KuoHong-Ji Lin Yuan-Chieh Tseng 《Journal of magnetism and magnetic materials》2011,323(15):1950-1953
Ni and Ni-NiO core-shell nano-arrays were fabricated by means of electroless deposition, where the latter was covered by a NiO shell of ∼10 nm by annealing the former at 350 °C for 30 min in an atmospheric condition. HRTEM showed that the NiO shell was developed at the expense of Ni at the array's surface. Ferromagnetic ordering of the Ni-NiO arrays was found to be suppressed compared with those of the less oxidized reference Ni arrays. This is attributed to the screening effect of the NiO shell, and weak ferromagnetism of inner Ni arrays resulted from the development of the NiO. X-ray absorption spectrum reveals that the reference Ni is partially oxidized. Also, X-ray magnetic circular dichroism suggests that the magnetic suppression of the Ni-NiO arrays is associated with a reduced spin moment. 相似文献
977.
C. Sekar S. PaulrajG. Krabbes M. KanagarajS. Arumugam Ravhi S. Kumar 《Journal of magnetism and magnetic materials》2011,323(23):3033-3037
MCu2O3 (M=Ca and Co) system has two-leg spin ladder structure similar to that of the prototype SrCu2O3 system except that the rungs are buckled with an angle of 123° and 105° for CaCu2O3 and CoCu2O3 compounds, respectively. We have synthesized powder samples of (Ca1−xCox)Cu2O3 (x=0.00-1.00) by the solid state reaction method and their structural and magnetic properties have been investigated. All the synthesized compounds crystallize in orthorhombic structure with space group Pmmn. Lattice parameters of (Ca1−xCox)Cu2O3 decrease with the increase in Co content. DC magnetic susceptibility χ(T) results of the end products CaCu2O3 and CoCu2O3 show antiferromagnetic transition (TN) at 27 and 215 K, respectively. Co doping into (Ca1−xCox)Cu2O3 enhances its TN systematically with increasing Co concentration. The χ(T) of CoCu2O3 shows a broad transition with the peak temperature around 215 K and it was found to be field independent up to 90 kOe. The ambiguity concerning the transition was ruled out by recording the temperature dependent X-ray diffraction pattern on CoCu2O3 system, which indicated that there is no structural transition in the investigated temperature range of 115-300 K. Further, specific heat measurement on CoCu2O3 confirms the magnetic phase transition by the appearance of a sharp peak at 215 K. 相似文献
978.
Gurinder Pal SinghParvinder Kaur Simranpreet KaurD.P. Singh 《Physica B: Condensed Matter》2011,406(24):4652-4656
Glass samples of composition xAl2O3-20PbO-(80−x)B2O3 and xWO3-xAl2O3-20PbO-(80−2x)B2O3 with x varying from 0% to 10% mole fraction are prepared by melt quench technique. The optical band gap decreases (from 3.21 to 2.37 eV) more for WO3-Al2O3-PbO-B2O3 glasses with an addition of WO3 content. The FTIR spectral studies have pointed out the conversion of structural units of BO3 to BO4 and WO4 to WO6 in these glasses. The increase in density from 4.51 to 5.80 g cm−3 for WO3-Al2O3-PbO-B2O3 glasses is observed with an increase in WO3 content. This is observed that the atomic structure changes more with the incorporation of WO3. This is due to the formation of WO6, WO4 and BO4 units. 相似文献
979.
P. Zaleski K. SzymańskiW. Olszewski M. BiernackaK. Perzyńska D. Satu?aA. Go J. Przewo?nikD.A. Zaj?c M. PylakL. Dobrzyński 《Physica B: Condensed Matter》2011,406(17):3196-3205
The lattice site occupation of 3d-type impurities in Cr3Si doped with Fe, Co and Ni were studied using the Extended X-ray Absorption Fine Structure (EXAFS) technique, X-rays and magnetic susceptibility measurements. The EXAFS measurements were performed particularly carefully on the K-edge of chromium and cobalt. EXAFS data strengthened by simulations of the spectra show unambiguously that the impurities are occupying mostly Cr-sites. The magnetic state of the alloys has been studied theoretically using the Wien2k code. It is observed that if calculations are not carried out on an appropriately fine mesh of points in k-space, one can get the result indicating ferromagnetism although the overall magnetic moment per formula unit is weak. 相似文献
980.