关于掺钕钇铝石榴石激光晶体色心问题的初步研究

本文通过多种实验手段,着重从机理方面,探讨了YAG:Nd激光晶体色心形成的原因和消除的方法。研究并解释了不同温度的退火,对于消除色心的作用,指出适当温度(900℃—1050℃)的退火,对该晶体的激光性能肯定会有所改善;研究了各个附加吸收峰的消长规律,指出色心形成的关键,在于出现了晶体的微观缺陷;在此基础上,提出了YAG:Nd晶体色心的能级摸型以及可能的结构摸型。     

Bi2Sr2CaCu2Oy单晶相结构的热不稳定性与…

在空气中４５０℃时Ｂｉ２２１２相开始发生相分解，在４５０－５５０℃温区出现的相分解情况与热处理气氛关系不大；而在更高的温度，其相分解在氧气中比在氮气中剧烈得多，另一方面，经４５０℃以下温度退火后，Ｔｃ和△Ｔｃ都基本不变；在４５０－５５０℃退火后Ｔｃ都升高到８５－８６Ｋ，而几乎与气氛和时间无关；经５５０℃以上温度退火后，晶的Ｔｃ都有升高，但经氮气退火后的Ｔｃ要比经氧气退火后的Ｔｃ高；热处理后单晶的超     

退火对Pb_(0.925)Ba_(0.075)Nb_2O_6-0.5wt.%TiO_2压电陶瓷结构及电学性能的影响

采用传统固相法制备了Pb0.925Ba0.075Nb2O6-0.5wt.%TiO2(PBN-T)压电陶瓷,并详细研究了退火对PBN-T陶瓷的结构、介电及压电性能的影响规律。实验中选取退火温度为500~800℃,退火时间为12~168h,退火气氛为空气中无额外Pb2+源、空气中含额外Pb2+源及氮气中含额外Pb2+源。结果表明:陶瓷的电学性能与退火参数密切相关,在600℃、氮气中含额外Pb2+源气氛下退火73h的陶瓷试样具有较佳性能,其居里温度为523℃,室温下压电常数为85pC/N,极化试样经500℃热处理后仍具有较高的压电常数82pC/N。     

稀土Yb~＋注入硅单晶所产生非晶层的快速热退火固相外延结晶研究

用卢瑟福背散射／沟道技术研究了３５０ｋｅｖＹｂ＋注入Ｓｉ（１００）所产生的表面非晶层在不同快速热退火温度下的固相外延结晶过程．实验结果表明，在８００℃－１０００℃的快速热退火温度下，在Ｙｂ＋射程范围以外的非晶层很容易固相外延结晶；但在同样退火温度下，在Ｙｂ＋射程分布范围内非晶层的团相外延结晶则非常缓慢．只有在退火温度高于１２００℃时，整个表面非晶层才完全消失．射程末端附近的复杂缺陷和缺陷杂质复合体是导致这两个不同结晶区域的主要原因．     

半绝缘砷化镓的热反型研究

高压液封直拉法生长的未掺杂半绝缘GaAs和水平法生长的掺Cr的半绝缘GaAs二种样晶在有As气氛和没有As气氛保护下分别在真空封管中在740℃退火4小时后,电学测量发现有As气氛保护的GaAs表面未出现热反型,而没有As气氛保护的GaAs表面出现热反型层。光致发光谱测量发现在热反型的样品中并没有出现与Mn_(Ga)相连系的1.41eV发射峰,而是与C_(As)相连系的1.490eV发射峰强度在退火后大大增强。一系列实验表明在真空退火后SI-GaAs表面低阻反型层的产生可能是由于在热退火过程中表面产生的大量V_(As)向内扩散,使表面层中的Ci填充V_(As)形成C_(As),从而使表面层的C_(As)受主浓度增加,导致形成低阻反型层。     

硫化反应生长ZnS薄膜的结构和光学性能研究

以物理气相沉积中的溅射和蒸发方法,在玻璃衬底上沉积Zn/S/Zn三层膜结构,然后在1atm压力的Ar气氛中退火制备ZnS薄膜,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见透射光谱对ZnS薄膜的晶体结构和光学性质及其生长机理进行研究。结果表明,在450℃温度下退火时,三层膜结构中高活性Zn和S容易发生硫化反应,形成的ZnS薄膜为立方晶体结构,沿(111)晶面择优生长;其ZnS特征吸收边出现在350nm附近,在可见光波长范围内,ZnS薄膜具有约80%的透光率;在450℃温度下退火后再于550℃温度下退火,所制ZnS薄膜的结晶性得到进一步提高。     

退火对大面积CdTe多晶薄膜薄膜的影响

对近空间升华法制备的大面积（30*40cm2）CdTe多晶薄膜用不同方法进行退火处理,用XRD、C～V、I～V等研究了退火条件,退火方式对薄膜结构和器件性能的影响。结果表明：刚沉积的CdTe多晶薄膜呈立方相,沿着（111）方向择优取向而退火后（111）（220）（311）等峰都有不同程度的增加。在纯氧气氛下,400℃退火还出现了新峰。随着退火温度的增加,电导激活能降低。经过连续退火装置在400℃下退火30分钟的电池,1/C2和V成线性关系,具有较高的掺杂浓度、较理想的二极管因子和较高的转换效率。     

退火对大面积CdTe多晶薄膜薄膜的影响

对近空间升华法制备的大面积(30×40 cm~2)CdTe多晶薄膜用不同方法进行退火处理,用XRD、C～V、I～V等研究了退火条件,退火方式对薄膜结构和器件性能的影响.结果表明:刚沉积的CdTe多晶薄膜呈立方相,沿着(111)方向择优取,向而退火后(111)(220)(311)等峰都有不同程度的增加.在纯氧气氛下,400℃退火还出现了新峰.随着退火温度的增加,电导激活能降低.经过连续退火装置在400℃下退火30分钟的电池,1/C~2和V成线性关系,具有较高的掺杂浓度、较理想的二极管因子和较高的转换效率.     

电子辐照MgAl2O4透明陶瓷诱导缺陷退火行为的研究

作者用能量为1.7MeV、束流强度0.7μA*cm-2、总注量6.3×1016cm-2的电子,辐照处理镁铝尖晶石透明陶瓷,并对辐照后的样品进行等时退火,利用UV-VIS和PAT测试表明,经电子辐照处理的样品在237nm和370nm处产生主要是由F心及V型色心引起的吸收带.通过退火可以消除由F心及V型色心引起的吸收峰,但消除F心的消除温度要高于V型色心,且在退火过程中形成F聚集心,F聚集心随F心聚集的增加将使其峰位向紫外移动.     

退火气氛对ZnO纳米颗粒的结构及发光特性的影响

在500℃且不同退火气氛(氮气、氧气)条件下,我们通过化学沉淀法成功制备了ZnO纳米颗粒.采用X射线衍射仪(XRD)、透射电子显微镜(TEM)、光致发光(PL)和拉曼光谱(Raman)研究退火气氛对ZnO纳米颗粒结构和发光特性的影响.实验结果表明,制得样品为具有六角纤锌矿结构的ZnO.从Raman和PL光谱可以观测到,退火气氛对ZnO纳米颗粒的结晶和发光特性都有很大的影响,氮气气氛下退火得到样品发光特性较好,缺陷较少,文中对其影响机制进行了讨论.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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