烧结温度对PSBN铁电陶瓷介电性能的影响

用普通的电子陶瓷工艺制备了ＰｂＯ－ＳｒＯ－ＢａＯ－Ｎｂ２Ｏ５（ＰＳＢＮ）系统民陶瓷，研究了ＰＳＢＮ系统铁电陶瓷的介电性能与烧结温度的关系，ＸＲＤ分析表明：ＰＳＢＮ系统铁电陶瓷的主晶相是Ｐｂ０．７Ｂａ０．３Ｎｂ２Ｏ６（ＰＢＮ）、Ｓｒ０．５Ｂａ０．５Ｎｂ２Ｏ６（ＳＢＮ）和Ｂａ０．２７Ｓｒ０．７５Ｎｂ２Ｏ５．７８（ＢＳＮ），将这一复杂的化学系统看作三元系固熔体，其中ＰＢＮ、ＳＢＮ和ＢＳＮ各相比例随烧结温     

（Ba_（1－x）Nd_x）TiO_3系陶瓷的电性能

研究了不同Ｎｄ３＋浓度（０．１ｍｏｌ％～２ｍｏｌ％）掺杂的ＢａＴｉＯ３陶瓷的电性能．结果表明，当Ｎｄ３＋浓度为０．１ｍｏｌ％～０．２ｍｏｌ％时，轻度Ｎｄ３＋掺杂的ＢａＴｉＯ３陶瓷是半导性，而当Ｎｄ３＋为０．６ｍｏｌ％～２ｍｏｌ％时呈绝缘性．ＢａＴｉＯ３陶瓷室温下的体电阻车ρＶ随Ｎｄ３＋浓度的变化呈Ｕ型特性曲线，当Ｎｄ３＋＝０．１５ｍｏｌ％时材料具有最低的ρＶ和最佳的正温系数（ＰＴＣＲ）效应，相应于最大的平均晶粒尺寸ＡＧＳ和介电常数ε。随着Ｎｄ３＋浓度的增加．材料的ε和居里常数Ｃ下降，同时ε与Ｃ值密切相关．ＳＥＭ照片显示了Ｎｄ３＋含量对材料晶粒尺寸的强烈影响．此外，还分析了ＺｒＯ２对（Ｂａ１－ｘＮｄｘ）ＴｉＯ３系陶瓷电性能的影响．     

BaO—PbO—Bi_2O_3－Nd_2O_3－TiO_2系陶瓷的物相和电性能

研究ＢａＯ－ＰｂＯ－Ｂｉ２Ｏ３－Ｎｄ２Ｏ３－ＴｉＯ２五元系统在８００～１２００℃烧结中物相变化和电性能．ＸＲＤ测试数据：１０００℃时ＢａＴｉＯ３消失，主晶相为ＢａＴｉ４Ｏ９、Ｂｉ４Ｔｉ３Ｏ１２和Ｎｄ２Ｔｉ２Ｏ７，ＢａＮｄ２Ｔｉ５Ｏ１４开始出现，１１００℃到１１５０℃，Ｂｉ４Ｔｉ３Ｏ１２在ＸＲＤ图上消失，ＢａＴｉ４Ｏ９和Ｎｄ２Ｔｉ２Ｏ７含量逐渐减少，ＢａＮｄ２ＴｉＯ１４逐渐增加；１２００℃时，ＸＲＤ图谱全部为ＢａＮｄ２Ｔｉ５Ｏ１４，证明该系统的主晶相ＢａＮｄ２Ｔｉ５Ｏ１４是由Ｎｄ２Ｏ３、ＴｉＯ２对具有微波特性的ＢａＴｉ４Ｏ９改性而得：铅含量增加，主晶相的ａ、ｂ二晶轴缩短．调整各组分及玻璃的含量，获得ε＝９０±５、损耗ｔｇδ≤３×１０－４、绝缘电阻ρｖ≥１０１２Ωｃｍ、电容量温度系数αｃ＝０±１５×１０－６／℃、中温（１１５０℃）烧结的ＮＰＯＭＬＣ瓷料．     

Bi_2O_3气相热扩散及其工艺条件对SrTiO_3基多功能陶瓷性能的影响

研究了Ｂｉ２Ｏ３气相扩散及其热扩散工艺条件对半导化ＳｒＴｉＯ３基陶瓷的介电性能（ε）、介电损耗（Ｄ）、非线性系数（α）及电阻率（ρ）的影响,用ＳＥＭ和ＥＰＡ对微观结构进行了观察和分析,结果显示Ｂｉ２Ｏ３主要集中在晶界附近．用ＳｒＴｉＯ３气相扩散法成功地获得了εａｐｐ＞５００００,Ｄ＜０．０１,α＞６．０,ρ＞５×１０１０Ω·ｃｍ的ＳｒＴｉＯ３基多功能陶瓷．     

Sol-gel法合成Bi_(1.6)Pb_(0.3)Sb_(0.1)Sr_2Ca_2Cu_3O_x体系的超导材料的研究

本文用Ｓｏｌ－ｇｅｌ法合成了Ｂｉ１．６Ｐｂ０．３Ｓｂ０．１Ｓｒ２Ｃａ２Ｃｕ３Ｏｘ体系的高ＴＣ超导原粉，对于不同的烧结时间，材料的超导性有不同程度的差异，（超导转变温度为１０８．３～１１６．１Ｋ）并与同种方法合成的Ｂｉ１．７Ｐｂ０．３Ｓｒ２Ｃａ２Ｃｕ３Ｏｘ体系进行了比较．用Ｓｏｌ－ｇｅｌ法，在Ｂｉ系中掺杂Ｐｂ，同样会缩短烧结时间（缩短６０ｈ），促进高温相的形成，同时掺杂Ｐｂ，Ｓｂ，形成超导材料所需的烧结时间进一步缩短（缩短１５３ｈ）．利用ＳＥＭ和Ｘ－ｒａｙ观察和分析了样品的形貌特征和物相结构．Ｓｏｌ－ｇｅｌ法具有工艺简单，烧结时间短，样品颗粒均匀、粒度小、组分易控等优点，在高ＴＣ超导材料中不失为一种行之有效的材料制备工艺．     

碳陶瓷复合材料抗氧化性能研究

将ＳｉＣ、Ｂ４Ｃ等碳化物陶瓷粉末与碳粉混合，采用热压烧结工艺制备碳陶瓷复合材料。对碳质量分数ｗＣ分别为０．１，０．２，０．３，０．４，０．５的５种碳陶瓷复合材料，在８００℃、１０００℃和１３００℃高温空气中的氧化性能进行了研究。结果表明，碳陶瓷复合材料在ｗＣ＜０．２时，抗氧化性很好；在ｗＣ＞０．３时，氧化速率加快。氧化后试样表面的ＸＲＤ谱和ＳＥＭ下的微观结构研究表明，氧化过程中碳陶瓷复合材料晶粒表面形成了ＳｉＯ２和Ｂ２Ｏ３固溶体薄膜，阻止了材料的进一步氧化。     

ZrO_2增韧Al_2O_3／SiCw陶瓷复合材料研究

研究了热压烧结Ａｌ２Ｏ３＋０．２０ＳｉＣｗ（体积分数，下同）－ＺｒＯ２（摩尔分数为０．０２Ｙ２Ｏ３，记为ＺｒＯ２（０．０２Ｙ））陶瓷复合材料的力学性能及韧化机制。结果表明，在Ａｌ２Ｏ３＋０．２０ＳｉＣｗ陶瓷中添加ＺｒＯ２（０．０２Ｙ）颗粒可使Ａｌ２Ｏ３＋０．２０ＳｉＣｗ材料进一步韧化和强化；室温下Ａｌ２Ｏ３＋０．２０ＳｉＣｗ＋０．３０ＺｒＯ２（０．０２Ｙ）复合材料的断裂韧性和抗弯强度分别可达１０．８５ＭＰａ·ｍ１／２和１２０７ＭＰａ。断口形貌和裂纹扩展途径的ＳＥＭ观察和ＸＲＤ分析结果表明，复合材料的增韧机制为裂纹偏转与绕过，晶须桥接与拔出以及相变增韧，并且晶须增韧与相变增韧具有良好的叠加性     

Ba＿（1－x）Sr＿xTiO＿3（0≤X≤1）固溶体的合成及性质研究

本文用四氯化钛、氯化钡、氯化锶分别作为钛、钡、锶源，用草酸作沉淀剂，首先在６５℃反应制得Ｂａ＿（１－Ｘ）Ｓｒ＿ＸＴｉＯ（Ｃ＿２Ｏ＿４）＿２·４Ｈ＿２Ｏ先驱物，在５Ｏ℃烘干后，再于８００℃的烧１小时，得到Ｂａ＿（１－Ｘ）Ｓｒ＿ＸＴｉＯ＿３白色粉末。经Ｘ─射线衍射分析证明，当ｘ分别为０和１时，产品分别为四方晶系钛酸钡和立方晶系钛酸锶，其它为由四方晶系向立方晶系过渡的固溶体。晶胞参数计算可知，该固溶体为完全互溶固溶体，结果符合Ｖｅｇａｒｄ定律。电镜形貌分析证明粒度为０．３～０．５μｍ。制陶试验证实，ＢａＴｉＯ＿３纯相掺锶后，居里点普遍前移，介电常数均有所提高，当产品组成为Ｂａ＿（０．９）Ｓｒ＿（０．１）ＴｉＯ＿３时，居里点前移２０℃，介电常数为７４００，比钛酸钡纯相的介电常数提高了４倍。     

SAG法Ba_（1－x）Sr_xTiO_3的介电性质

ＸＲＤ法分析和介电测量结果表明，ＳＡＧ法Ｂａ１－ｘＳｒｘＴｉＯ３（ｘ＝０、０．３、０．５和０．７）微粉和陶瓷的室温结构为立方相．其居里温度明显低于相应Ｂａ１－ｘＳｒｘＴｉＯ３晶体或常规工艺陶瓷的值，但居里温度仍随着Ｓｒ２＋含量的增加而线性下降．晶粒含杂质Ｆｅ３＋以及表面富钡可能使其晶格立方化，从而使居里温度下降以及三方－正交和正交－四方铁电相变消失．     

弛豫铁电体中激活能的讨论

从德拜弛豫理论出发,通过介电温度谱得到弛豫时间温度谱,由此计算弛豫铁电体的弛豫激活能Ｑ和指数前因子τ０。计算得Ｐｂ（Ｓｃ０．５Ｔａ０．５）Ｏ３（ＰＳＴ）单晶（有序度Ｓ＝０．３５）,ＰＳＴ陶瓷（Ｓ＝０．４０）,０．８５Ｐｂ（Ｚｎ１／３Ｎｂ２／３）Ｏ３－０．１５ＢａＴｉＯ３（ＢＺＮ－ＢＴ）陶瓷,０．９３Ｐｂ（Ｍｇ１／３Ｎｂ２／３）Ｏ３－０．０７ＰｂＴｉＯ３（ＰＭＮ－ＰＴ）陶瓷４种典型弛豫铁电体激活能Ｑ     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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