Effects of Si doping on the structural and electrical properties of Ge2Sb2Te5 films for phase change random access memory

The effects of Si doping on the structural and electrical properties of Ge₂Sb₂Te₅ film are studied in detail. Electrical properties and thermal stability can be improved by doping small amount of Si in the Ge₂Sb₂Te₅ film. The addition of Si in the Ge₂Sb₂Te₅ film results in the increase of both crystallization temperature and phase-transition temperature from face-centered cubic (fcc) phase to hexagonal (hex) phase, however, decreases the melting point slightly. The crystallization activation energy reaches a maximum at 4.1 at.% and then decreases with increasing dopant concentration. The electrical conduction activation energy increases with the dopant concentration, which may be attributed to the increase of strong covalent bonds in the film. The resistivity of Ge₂Sb₂Te₅ film shows a significant increase with Si doping. When doping 11.8 at.% of Si in the film, the resistivity after 460 °C annealing increases from 1 to 11 mΩ cm compared to the undoped Ge₂Sb₂Te₅ film. Current-voltage (I-V) characteristics show Si doping may increase the dynamic resistance, which is helpful to writing current reduction of phase-change random access memory.     

Characteristics of Nd：GdVO4 Laser with Different Nd-Doping Concentrations

We report the properties of a compact diode-pumped continuous-wave Nd：GdV04 laser with a linear cavity and different Nd-doped laser crystals. In a 0.2at.% Nd-doped Nd：GdVO4 laser, 1.54 W output laser power is achieved at 912nm wavelength with a slope efficiency of 24.8% at an absorbed pump power of 9.4W. With 0.3at.% Nd-doping concentration, we can obtain the either single-wavelength emission at 1064nm or 912nm or the dual-wavelength emission at 1064nm and 912nm by controlling the incident pump power. From an incident pump power of 11.6 W, the 1064nm emission between ^4Fa/2 and ^4I11/2 is suppressed completely by the 912nm emission between ^4Fa/2 and ^4I9/2. We obtain 670 mW output of the 912nm single-wavelength laser emission with a slope efficiency of 5.5% by taking an incident pump power of 18.4 W. Using a Nd：GdV04 laser with 0.4at.% Nd-doping concentration, we obtain either the single-wavelength emission at 1064nm or the dual-wavelength emission at both 1064nm and 912nm by increasing the incident pump power. We observe a strong competition process in the dualavelength laser.     

Characterization of iron surface modified by 2-mercaptobenzothiazole self-assembled monolayers

A self-assembled monolayer of 2-mercaptobenzothiazole (MBT) adsorbed on the iron surface was prepared. The films were characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared reflection spectroscopy (FT-IR) and scanning electron microscopy (SEM). Besides, the microcalorimetry method was utilized to study the self-assembled process on iron surface and the adsorption mechanism was discussed from the power-time curve. The results indicated that MBT was able to form a film spontaneously on iron surface and the presence of it could protect iron from corrosion effectively. However, the assembling time and the concentration influence the protection efficiency. Quantum chemical calculations, according to which adsorption mechanism was discussed, could explain the experimental results to some extent.     

New Non-Linear Inequalities for Flag-Vectors of 4-Polytopes

In this paper we prove four new (infinite) lists of quadratic inequalities, and four cubic inequalities, for the flag f-vectors of 4-polytopes. These extend and supplement the only four currently known non-linear inequalities, which were proved by Bayer in 1987. The new lists of inequalities for flag f-vectors yield new lists of inequalities for f-vectors of 4-polytopes. Using the latter, we managed to improve an estimate discovered by Hoppner and Ziegler concerning upper bounds of f₁ in terms of f₀ and f₃.     

等效电流偶极子(ECD)模型在MCG场源定位中的应用

等效电流偶极子(ECD)模型具有简要明确性，已经在心磁图(MCG)的逆问题中，如确定WPW综合症、心脏异常搏动根源、心律失常等方面，得到广泛应用．在多通道体表电势图(BSPM)的测量中也应用ECD．本文讨论用ECD的定位方法，临床研究仿真对ECD获得结果的描述，造影与动物研究和体导体模型的影响．     

Nonvolatile photorefractive holographic recording in Sc:Ce:Cu:LiNbO3

In this paper experimental studies of nonvolatile photorefractive holographic recording in Ce:Cu:LiNbO₃ crystals doped with Sc(0,1,2,3 mol%) were carried out. The Sc:Ce:Cu:LiNbO₃ crystals were grown by the Czochralski method and oxidized in Nb₂O₅ powders. The nonvolatile holographic recording in Sc:Ce:Cu:LiNbO₃ crystals was realized by the two-photon fixed method. We found that the recording time of Sc:Ce:Cu:LiNbO₃ crystal became shorter with the increase of Sc doping concentration, especially doping with Sc(3 mol%), which exceeds the so-called threshold, and there was little loss of nonvolatile diffraction efficiencies between Sc(3 mol%):Ce:Cu:LiNbO₃ and Ce:Cu:LiNbO₃ crystals.     

The Synthesis of Glycoglycerolipids

A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained.     

凸度量空间中单值和集值映象的公共不动点定理

§ 1.　Introduction　　Anecessaryandsufficientconditionandasufficientconditiontoensurethataset valuedmappingandasingle valuedmappinginacompletemetricspaceandacompleteconvexmetricspacehavingacommonfixedpointarerespectivelygivenin [1 ] .Meanwhilethemainresultsin[2 ]— [5]areimprovedandextendedin [1 ] .Inthispaper ,theexistenceatcommonfixedpointsoftwoset valuedmappingandasing valuedmappingwerestudied ,andthecorrespond ingresultsin [1 ]— [5]wereextendedandimproved .Let(X ,d)beanon emptymetricspa…     

支持下一代无线宽带应用自适应QoS模型的研究

作为真正完整的下一代网络 ( NGN,Next Generation Network)解决方案 ,NGN需要在固定通信领域和移动通信领域都能够支持综合多媒体特性。NGN中的新一代移动通信网承载在开放式、层次化结构的分组交换网络之上 ,能够为用户提供端到端的 Qo S解决方案。本文分析了下一代移动通信系统中多媒体宽带应用的 Qo S问题 ,从无线通信系统的多层次结构出发 ,建立了业务流的 Qo S指标评判体系 ,为下一代网络中的无线宽带应用提供了一种自适应Qo S控制模型