(PSTT10/45)4 多层薄膜铁电性研究

以LaNiO3做缓冲层,用射频磁控溅射法在SiO2/Si(100)衬底上制备出[0.9Pb(Sc0.5Ta0.5)O3-0.1PbTiO3/0.55Pb(Sc0.5Ta0.5)O3-0.45PbTiO3]4铁电多层薄膜.采用两步法在峰值温度800 ℃对薄膜进行退火.通过x射线衍射分析了薄膜的物相结构,通过电滞回线和漏电流曲线对薄膜的铁电性能进行了测量.研究发现,薄膜展现出高度(100)取向的钙钛矿结构和增强的铁电性,其剩余极化2Pr=26.2 μc/cm2,矫顽场2Ec=53.9 kV/cm,100 kV/cm下漏电流密度为1.87×10-4A/cm2.分析了铁电性增强和漏电流增大的可能原因.     

0.9Pb(Sc1/2Ta1/2)O3-0.1PbTiO3/0.65Pb(Mg1/3Nb2/3) O3-0.35PbTiO3 多层薄膜的制备及铁电性研究

以LaNiO3做缓冲层,用射频磁控溅射法在SiO2/Si(100)衬底上制备出0.9Pb(Sc1/2Ta1/2)O3 -0.1PbTiO3/0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3铁电多层薄膜.采用两步法在峰值温度650℃和700℃对薄膜进行退火.通过电滞回线和漏电流曲线对薄膜的铁电性能进行了测量.研究发现,650 ℃退火的薄膜有较好的铁电性,其剩余极化2Pr=9.5 μc/cm2,矫顽场2Ec=42.2 kV/cm,100 kV/cm场强下漏电流密度为31μA/cm2.700 ℃退火的薄膜铁电性有所下降,2Pr=3.1 μc/cm2,但薄膜却具有很低的矫顽场,2Ec=22.6 kV/cm.分析认为,铁电性的退化与高温下薄膜中异质结间的相互作用及挥发性元素Pb和Mg的损失密切相关.     

Nd掺杂对Bi4Ti3O12单晶的结构和电学性能的影响

采用高温溶液生长法生长铁电Bi4-xNdxTi3O12(BNdT)单晶,并研究了BNdT的结构和电学性能.XRD结构精修的结果表明Nd掺杂将导致晶格常数和晶胞体积发生变化,铁电性能的测试表明Nd掺杂降低了BNdT单晶的剩余极化,BNdT的自发极化的估算和铁电测量结果有着相同的变化趋势.Nd的A位掺杂同时也导致BNdT单晶沿各个方向漏电流密度的减小,而由于(Bi2O2)2 层的存在,BNdT单晶沿c方向显示出更低的漏电流密度.     

BiFeO_3薄膜的so-lgel制备及其铁电性能研究

采用sol-gel方法在Pt(111)/Ti/SiO2/Si(100)衬底上制备出了(100)择优取向的BiFeO3薄膜.XRD研究表明,600～650℃退火的薄膜结晶较好.AFM形貌显示,650℃退火的薄膜中等轴状晶粒大小均匀(直径100～150nm),薄膜较为致密.电学性能测量结果表明,650℃退火、厚度为840nm的薄膜的2Pr值为2.8mC/cm2;在50kV/cm外加电场下,漏电流为2.7×10-5 A/cm2.电流-电压特性显示,在欧姆区之上,薄膜的主要导电机制为波尔-弗兰克尔发射导电.     

Ferroelectric, dielectric, and optical properties of Nd-substituted Bi4Ti3O12 nanoparticles synthesized by sol-gel method

This paper reports the synthesis of neodymium substituted bismuth titanate nanoparticles(BNdT) for ferroelectric random access memory(Fe RAM) based applications using sol-gel route. X-ray diffraction pattern showed that the BNdT nanoparticles exhibited perovskite structure with orthorhombic phase. The microstructure of the BNdT nanoparticles showed that the grains were in spherical structure with a bi-modal distribution of spheres. Dielectric constant and dielectric loss of BNdT nanoparticles were measured in the frequency range 100 Hz to 100 kHz. Nd-substituted BNdT nanoparticles showed the high remanent polarization(P_r=33.2 μC/cm~2, Ec=62.5 kV/cm) than pure bismuth titanate(BT)(P_r=14.6 μC/cm~2, Ec=182.8 kV/cm) ideal for FeRAM based applications. The occurrence of red shift in photoluminescence(PL) spectrum is considered to be due to the isomerisation that may occur from the heating of samples.     

钨青铜型Ca_(0.28)Ba_(0.72)Nb_2O_6单晶的正常弛豫铁电相转变研究

研究了大块Ca0.28Ba0.72Nb2O6(CBN-28)单晶沿[001]方向的铁电介电性能.结果表明,CBN-28单晶的自发极化、剩余极化和矫顽场分别为35.3μC/cm2,32.2μC/cm2和38.1kV/cm.在室温下频率f=10kHz时,介电常数(εr=195,介电损耗tgδ=0.32.变温的介电谱显示该单晶在252℃附近发生了正常铁电体向弛豫铁电体的转变.低频时在325℃～500℃范围内出现了具有弛豫特征的介电反常.120℃附近有一由氧空位的迁移引起的介电弛豫损耗峰,由此计算得激活能为1.19eV.通过阻抗谱计算,在500℃～560℃范围内的电导激活能为1.33eV.     

优化的B位离子氧化物共烧法制备钙钛矿结构的PYN-PZN-PT三元铁电陶瓷

通过优化B位离子氧化物共烧方法,成功制备出具有纯钙钛矿结构的Pb(Yb1/2Nb1/2)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3(PYN-PZN-PT)三元铁电固溶体陶瓷,有效地抑制PZN基陶瓷制备过程中烧绿石相的形成.选取(0.48-x)PYN-0.52PZN-xPT(x=0.24~0.28),对三元体系的相结构、铁电、压电和介电性能进行了研究.结果表明:烧结得到的陶瓷致密均匀无杂相,晶粒尺寸2~4μm;随着PT含量的增加,物相经历了从三方相到三方和四方相共存的准同型相界(MPB)、再到四方相的结构演变;MPB附近的组分具有优异的性能,性能最好的组分是0.21PYN-0.52PZN-0.27PT,其压电系数d33=550pC/N,室温介电常数ε′=2 070,矫顽场Ec=19.9kV/cm,居里温度TC=260℃;陶瓷样品的介电温谱表现出介电弥散以及介电峰的展宽等类弛豫体的特点.     

冷烧并退火制备(Bi0.5Na0.5)0.94Ba0.06TiO3无铅陶瓷及其结构与电学性能

采用冷烧并退火方法制备了(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃无铅陶瓷,探究了退火温度对陶瓷物相,显微组织,介电、铁电及压电性能的影响。结果表明：冷烧并退火所得陶瓷均呈纯钙钛矿结构,在180℃冷烧所得坯体的相对密度为71.8%。冷烧坯体经1 000～1 100℃退火所得陶瓷的相对密度为81.7%～97.1%,平均晶粒尺寸为600～800 nm,介电弥散因子为1.85～1.96。在1 025、1 050、1 075和1 100℃退火陶瓷的退极化温度分别为130、137、135和123℃;在1 075℃退火陶瓷具有最大的饱和极化强度和剩余极化强度,分别为60.9μC/cm²和51.8μC/cm²。与常规固相法烧结的(Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃陶瓷的击穿场强(<75 kV/cm)相比,冷烧...     

溶胶-凝胶法制备0．85Pb（Mg1／3Nb2／3）O3—0．15PbTiO3铁电陶瓷及其性能研究

以无机盐和氧化物为原料,柠檬酸和乙二胺四乙酸(EDTA)为复合螯合剂,乙二醇为溶剂,采用溶胶-凝胶法制备了0.85Pb(Mg1/3Nb2/3)O3-0.15PbTiO3(PMN-PT)铁电陶瓷粉体及其烧结体.并通过XRD和SEM分析了PMN-PT钙钛矿相的形成和烧结体的显微结构.讨论了不同烧结温度对陶瓷显微结构、介电、铁电及压电性能的影响.结果表明采用溶胶-凝胶法制备的PMN-PT陶瓷适宜烧结温度为1 100℃,比常规固相合成法制备PMN-PT陶瓷的温度低100～200℃,且该条件下烧结的陶瓷性能优异:d33=252 pC/N,Pr=17.8 μC/cm2.     

Bi_(3.15)Nd_(0.85)Ti_3O_(12)薄膜的取向生长及其铁电介电特性研究

用sol-gel工艺直接在Pt/Ti/Si O2/Si衬底上制备出了a轴择优取向(α(100)=62%)和高c轴取向(α(100)=96%)的Bi3.15Nd0.85Ti3O12(BNdT)薄膜.发现BNdT薄膜的铁电介电性能强烈依赖于晶粒取向.a轴择优取向BNdT薄膜的2Pr和εr值最高,分别为65μC/cm2和343(100kHz处);随机取向薄膜的2Pr和εr值为34μC/cm2和331;而高c轴取向薄膜的2Pr和εr值最低,分别为23μC/cm2和218.上述结果表明,BNdT的自发极化矢量靠近a轴.纯a轴取向BNdT薄膜的2Pr值可估算为84μC/cm2.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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     

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