锰-铝-碳永磁合金的磁性与组织

研究了锰67.61～73.58％,碳0.51～0.96％范围内的锰—铝—碳永磁合金的磁性、显微组织和亚稳态铁磁性τ相的稳定性。从高温平衡态ε相控速冷却或淬火随后回火均能获得τ相,但控速冷却样品的磁性能低。由于碳的作用,使ε相转变减缓,ε相区下移,临界温度降低80℃～100℃。τ相的稳定性随锰、碳含量而变化,在合适的含C量范围内,随Mn含量增加,τ相稳定性降低;淬火样品在不同温度加热60分钟,组成为71.76％Mn0.96％C的样品700℃τ相开始分解;组成为72.48％Mn0.7％C的样品600℃τ相开始分解。     

添加硼对La-Mg-Ni系(PuNi3-型)贮氢合金微观结构及电化学性能的影响

为了提出La-Mg-Ni(PuNi3型)系贮氢合金的电化学循环稳定性,在La2Mg(Ni0.85Co0.15)9合金中添加微量的B,用铸造及快淬工艺制备La2Mg(Ni0.85Co0.15)9Bx(x=0,0.05,0.10,0.15,0.20)贮氢合金,分析测试铸态及快淬态合金的微观结构与电化学性能,研究硼对合金微观结构及电化学性能的影响。结果表明:铸态合金具有多相结构,包括主相(La,Mg)Ni3相(PuNi3型)和LaNi5相,一定量的LaNi2相和微量的Ni2B相经快淬处理后,Ni2B相消失,且其他相的相对量随淬速的变化而变化。硼的加入提高了铸态及快淬态合金的循环稳定性,但使铸态合金的容量下降;铸态合金的电化学容量随B含量的增加单调下降,而快淬态合金的容量随B含量的增加有一极大值,B对铸态及快淬态合金电化学性能的影响机理是完全不同的。     

纳米复合永磁合金Nd9Fe85-xB6Mnx的XAFS研究

为了研究淬火速度及Mn掺杂对纳米复合Nd-Fe－B磁性材料微结构的影响,利用XAFS技术对不同淬火速度的Nd9Fe84.5B6Mn0.5样品及退火和未退火的Nd9Fe84.5B6Mn0.5（x－0．5和1．0）样品,进行了Fe原子局域结构的分析。结果表明,纳为复合Nd9Fe84.5B6Mn0.5噘性材料随着淬火速度的增另,Fe原子的最近邻配位距离单上,而配位无序度的变化较为复杂。退火前,掺杂微量Mn原子进入磁体的Nd2Fe14B主相晶体结构,掺杂量不同对主相局域结构的影响有明显差异。退火后,Mn原子退出磁体的主相结构,进入晶界或产生富集,没有发现掺杂量不同对主相局域 结构的影响,但对整个磁体的磁性仍然有不同的影响。     

LaMn_(1-x)Te_xO_(3+δ)的反常磁输运现象分析

通过固体反应法制备出了Mn位Te掺杂氧化物:LaMn1-xTexO3+δ.X光电子能谱测量结果表明Te离子在样品中具有Te4+价态,Mn3+离子因受富氧及Te4+替换影响而部分转变成Mn2+和Mn4+,以致LaMn1-xTexO3系列样品中同时存在Mn2+,Mn3+,Mn4+三种价态,当Mn3+在样品中的含量远大于Mn2+及Mn4+两者含量和时,样品则具有绝缘态特征,但当Mn3+含量与Mn2+及Mn4+两者含量和相当时,样品则随温度的升高而产生了金属-绝缘态相变.对于这种反常的磁输运现象,用双交换(DE)机制进行了的分析和讨论.     

双层钙钛矿锰氧化物La1.2-xDyxSr1.8Mn2O7(x=0.00,0.05)的磁性和类Griffiths研究

采用传统固相反应法制备多晶样品La1.2-xDyxSr1.8Mn2O7(x=0.00,0.05),通过测量样品的磁化强度与温度变化曲线(M-T)以及不同温度下磁化强度与外加磁场的变化曲线(M-H)对样品的磁性和类Griffiths 相进行了研究. 研究发现,两个样品分别在15-400 K 的测量温度范围内,在类Griffiths 相温度(TG≈368、360 K)以上处于纯顺磁态;在奈尔温度(TN≈210、183 K)-TG范围内,系统处于反铁磁-铁磁共存态,存在类Griffiths 相,随温度的降低,样品的铁磁性逐渐增强;在TN以下,随温度的降低,铁磁性逐渐减弱,反铁磁性增强,样品呈现出了团簇玻璃行为. 通过对比两个样品后发现,掺杂后样品x=0.05 比未掺杂样品的磁性、三维长程居里温度(Tc3D)和类Griffiths相温度(TG)均降低,这是由于Dy3+离子半径比La3+离子半径小,掺杂之后导致晶格畸变所引起的.     

钆取代M型钡铁氧体的研究

采用草酸盐共沉淀工艺制备了组成为(χ/2)Gd_2O_3+(1-χ)BaO+6Fe_2O_3的草酸盐粉料,预烧、成型后在不同温度下进行烧结。用热中子透射法测定了样品中的含钆量。用 X 射线衍射物相分析和磁分析方法研究了烧结过程中生成物的相组成及其相变。当χ≤0.12时,在1310℃烧结得到纯 M 相。在1400℃烧结得到的样品中,当χ≤0.15时为 X 相;当0.4≤χ≤0.6时主要相为 W 相。测量了样品的磁性、电阻率和 M(?)ssbauer 谱。发现在 X 结构化合物中,室温下的磁晶各向异性常数随含钆量的增加而增加;W 相化合物的居里温度比文献报导的数据高80℃左右。讨论了在含钆的 M 型六角铁氧体中,Gd~(3+)对磁性和电阻率的影响,以及 Gd~(3+)和 Fe~(3+)间的交换作用。     

Pr2Fe14B／α—Fe纳米复合永磁的淬态组织对回火时相变过程和磁性的影响

纳米复合永磁材料的原始淬态组织对最终的显微组织结构和磁性有着决定性的影响,为了弄清其影响规律,研究了成分为Pr7Fe88B5的双相纳米复合永磁材料的淬态组织在回火时相转变的过程和晶化后的组织结构及磁性。X射线谱和Mossbauer谱的研究结果表明,在不同辊速下制得的快淬带样品的组织结构是不同的。原始淬态组织的不同导致回火时的不同相变过程,它们分别是（1）非晶相Am Pr2Fe14B α-Fe→Pr2Fe14B α-Fe;（2）非晶相Am α-Fe→(Am)′ α-Fe→α-Fe 1:7相＋Pr2Fe14B→Pr2Fe14B α-Fe;(3)Am→Am′＋α－Fe→1:7相＋α-Fe→Pr2Fe14B α-Fe。虽然样品最终的相组成均为α-Fe和Pr2Fe14B,但不同原始态的样品晶化后的显微组织和磁性并不同相同。     

Na+掺杂对Ca2FeMoO6双钙钛矿磁性的影响

采用溶胶-凝胶法制备了Ca2-xNaxFeMoO6(0≤x≤0.4)系列样品.利用X-射线衍射和X-射线精修分析了样品的晶体结构和晶胞参数随Na含量的变化关系.利用超导量子干涉仪和振动样品磁强计分别研究了样品的低温磁性和高温磁性,得到了样品的磁化强度随温度和掺杂量的变化规律,测量了样品的居里温度.初步探索了Na+掺杂后所引入的空穴掺杂效应.     

Fe-Ni25～30%合金的相变和磁性

本文用热膨胀分析、X 射线衍射、金相组织观察和磁性测量等方法研究了 Fe-Ni 20～30％ 的合金及含少量 Mn 的 Fe-Ni 合金在加热和冷却过程中的相变及磁性,讨论了合金成份、组织结构与磁性的关系。     

Pr2Fe14B/α-Fe纳米复合永磁的淬态组织对回火时相变过程和磁性的影响

纳米复合永磁材料的原始淬态组织对最终的显微组织结构和磁性有着决定性的影响,为了弄清其影响规律,研究了成分为Pr7Fe88B5的双相纳米复合永磁材料的淬态组织在回火时相转变的过程和晶化后的组织结构及磁性.X射线谱和Mossbauer谱的研究结果表明,在不同辊速下制得的快淬带样品的组织结构是不同的.原始淬态组织的不同导致回火时的不同相变过程,它们分别是(1)非晶相Am+Pr2Fe14B+α-Fe→Pr2Fe14B+α-Fe;(2)非晶相Am+α-Fe→(Am)′+α-Fe→α-Fe+1:7相+Pr2Fe14B→Pr2Fe14B+α-Fe;(3)Am→Am′+α-Fe→1:7相+α-Fe→Pr2Fe14B+α-Fe.虽然样品最终的相组成均为α-Fe和Pr2Fe14B,但不同原始态的样品晶化后的显微组织和磁性并不相同.     

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     

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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