Bi2222相单晶生长的相关问题研究

从名义组份Ｂｉ２．４Ｓｒ２ＰｒＣｕ２Ｏｙ生长出一种新的Ｂｉ２２２２相单晶，其实际组份测定为Ｂｉ２Ｓｒ１．５Ｐｒ２．５Ｃｕ２Ｏｙ．用Ｘ射线衍射对单晶的结构进行了表征，并且研究了该单晶生长中Ｂｉ２２０１和Ｂｉ２２１２相的交生等相关问题．另外，如果从名义组份为Ｂｉ２．４Ｓｒ１．５Ｐｒ２．５Ｃｕ２Ｏｙ出发，得到的却是Ｐｒ２ＣｕＯ４单晶．     

Bi系高Tc超导材料的核四极共振（NQR）研究

用标准固相反应法，我们制备了Ｂｉ１．６Ｐｂ０．４Ｓｒ２Ｃａ２Ｃｕ３Ｏｙ和Ｂｉ２ＣａＣｕ２Ｏｙ纯相样品，在液氮温度下测量了Ｃｕ－ＮＱＲ和Ｂ－ＮＱＲ静态谱，发现ＮＱＲ谱都为大宽包，Ｃｕ－ＮＱＲ谱线位置反映铜原子所处的氧环境，Ｂｉ２Ｓｒ２Ｃｕ２Ｏｙ的ＮＱＲ谱宽反映其调制结构，Ｂｉ１．６Ｐｂ０．４Ｓｒ２Ｃａ２Ｃｕ３ＯｙＮＱＲ谱宽取决于其掺杂浓度。由于电场梯度弥散很大，Ｂｉ－ＮＱＲ谱很难观察。     

PdCl_2/SiO_2和Pd-B/SiO_2非晶态合金催化剂的Raman光谱表征

采用共焦显微Ｒａｍａｎ光谱和Ｘ－射线衍射方法表征了负载型ＰｄＣｌ２／ＳｉＯ２和Ｐｄ－Ｂ／ＳｉＯ２非晶态合金催化剂的结构。结果表明ＰｄＣｌ２分散在ＳｉＯ２载体上后,与载体表面的相互作用使其在室温时即发生β→α构型转变。Ｐｄ－Ｂ／ＳｉＯ２非晶态合金的Ｒａｍａｎ光谱在３００－５００ｃｍ－１区域内呈现一大的弥散峰。与无负载Ｐｄ－Ｂ非晶态合金比较初步认定该弥散峰与Ｐｄ－Ｂ键振动有关,温度升高Ｐｄ－Ｂ／ＳｉＯ２催化活性下降,其主要原因为Ｐｄ－Ｂ／ＳｉＯ２非晶态合金在高温下逐渐晶化为Ｐｄ金属所致。ＰｄＣｌ２与ＳｉＯ２载体表面的相互作用使其具有较高的分散性,由此还原制备的Ｐｄ－Ｂ／ＳｉＯ２非晶态合金较之无负载Ｐｄ－Ｂ非晶态合金更加微细化,因而具有更大的活性比表面     

Prism Material Dispersion Effects on the Total Dispersion of Prism Pair System

ＰｒｉｓｍＭａｔｅｒｉａｌＤｉｓｐｅｒｓｉｏｎＥｆｅｃｔｓｏｎｔｈｅＴｏｔａｌＤｉｓｐｅｒｓｉｏｎｏｆＰｒｉｓｍＰａｉｒＳｙｓｔｅｍＳＵＮＨｏｎｇＷＡＮＧＣｈｉｎｇｙｕｅ（ＵｌｔｒａｆａｓｔＬａｓｅｒＬａｂｏｒａｔｏｒｙ，ＣｏｌｅｇｅｏｆＰｒｅ...     

PdCl2／SiO2 Pd—B／SiO2非晶态合金催化剂的Ramman光谱表征

采用共焦显微Ｒａｍａｎ光谱和Ｘ－射线衍射方法表征了负载型ＰｄＣｌ２／ＳｉＯ２和Ｐｄ－Ｎ／ＳｉＯ２非晶态合金催化剂的结构。结果表明ＰｄＣｌ２分散在ＳｉＯ２载体上后,与载体表面的相互作用使其在室温时即发生β→α构型转变。Ｐｄ－Ｂ／ＳｉＯ２非晶态合金的ｒａｍａｎ光谱在３００－５００ｃｍ＾－１区域内呈现一大的弥散峰。与无负荷Ｐｄ－Ｂ非晶态合金比较初步认定该弥散峰与Ｐｄ－Ｂ键振动有关,温度升高Ｐｄ－Ｂ／Ｓｉ     

静高压下Cu－Si块状纳米合金的制备与表征

用压淬的方法，在６ＧＰａ静高压下，以２００Ｋ／ｓ的冷却速率冷却熔融状态的Ｃｕ＿（７０）Ｓｉ＿（３０）合金，制备出块状Ｃｕ－Ｓｉ纳米合金．Ｘ射线衍射和透射电子显微镜分析表明：该纳米合金由γ－Ｃｕ＿５Ｓｉ和一未知相组成，未知相为简单立方晶体，晶格常数α＝０．８５３５ｎｍ，其热力学状态为亚稳态。并对静高压下块状纳米合金的形成机理进行了探讨。     

Pure Dispersive Optical Bistability of Four－level System in a Fabry－Perot Cavity

ＰｕｒｅＤｉｓｐｅｒｓｉｖｅＯｐｔｉｃａｌＢｉｓｔａｂｉｌｉｔｙｏｆＦｏｕｒ－ｌｅｖｅｌＳｙｓｔｅｍｉｎａＦａｂｒｙ－ＰｅｒｏｔＣａｖｉｔｙ￥ＪＩＹｉｎｇ；ＬＩＮＦｕｃｈｅｎｇ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈ...     

SiC在高温高压下溶于金属触媒中形成金刚石的原子过程

从原子间相互作用及运动出发，阐明ＳｉＣ在高温高压下溶于金属触媒中形成金刚石的原子过程，并在此基础上进而阐明Ｎｉ７０Ｍｎ２５Ｃｏ５是促使ＳｉＣ形成金刚石的高效率触媒合金。日本文部省的资助     

Influence on Transmission Properties of Solitons by Stochastic Variation of System Parameters and Interaction

ＩｎｆｌｕｅｎｃｅｏｎＴｒａｎｓｍｉｓｓｉｏｎＰｒｏｐｅｒｔｉｅｓｏｆＳｏｌｉｔｏｎｓｂｙＳｔｏｃｈａｓｔｉｃＶａｒｉａｔｉｏｎｏｆＳｙｓｔｅｍＰａｒａｍｅｔｅｒｓａｎｄＩｎｔｅｒａｃｔｉｏｎＣＨＥＮＭｉｎｇｈｕａ；ＷＥＮＹａｎｇｊｉｎ；ＹＡＮＧＸｉ...     

Bi2201体系中Raman散射、微结构和输运性质研究

利用Ｘ－光衍射,电子衍射,Ｒａｍａｎ散射和电阻率等手段对多晶样品Ｂｉ１．８Ｐｂ０．２Ｓｒ２Ｃｕ１－ｘＦｅｘＯｙ,Ｂｉ１．８Ｐｂ０．２Ｓｒ１．６＋ｘＬａ０．４－ｘＣｕ１－ｘＦｅｘＯｙ的结构和性能进行了研究。结果表明：Ｂｉ２２０１体系的调制特征与客外氧的多少无关,６２５ｃｍ＾－１附近的Ｒａｍａｎ峰受‘电荷转移’效应和调制结构变化的显著影响,晶体的微结构变化强烈影响体系的超电性和输运性质。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.