材料期刊网

Gammasphere上裂变丰中子核核结构若干前沿领域的新进展(II:第三和第四部分)

罗亦孝 , J.H.Hamilton , J.O.Rasmussen , A.V.Ramayya , C.Goodin , A.V.Daniel , N.J.Stone , 朱胜江 , J.K.Hwang , 刘少华 , C.J.Beyer , 李科 , H.L.Crowell , D.Almehed , S.Frauendorf , A.Covello , V.Dimitrov , 张敬业 , 车兴来 , 姜卓 , D.Fong , A.Gelberg , I.Stefanescu , A.Gargano , E.F.Jones , P.M.Gore , I.Y.Lee , G.M.Ter-Akopian , Yu.Ts.Oganessian , M.A.Stoyer , R.Donangelo , 马文超 , J.D.Cole , J.Kormicki , 张学谦 , S.C.Wu , J.Gilat , T.N.Ginter , S.J.Asztalos

原子核物理评论

使用Gammasphere多探测器系统对252Cf裂变源瞬发7射线进行γ-γ-γ和γ-γ(θ)符合测量,A～100(Z～40,N＞56)丰中子核区关于形状过渡、形状共存和形状突变的深入研究获得了新的进展.奇-Z核的系统研究揭示了从Z=39(Y)同位素的轴对称大四极形变到Z=43(Tc),44(Ru)和45(Rh)同位素中具有中等四极形变之大三轴形变的过渡.Nb(Z=41)同位素具有过渡核的特征.根据邻近同位素和同中素带交叉信息的系统性及推转壳模型(CSM)计算,Tc和Rh偶-N同位素中观察到的带交叉产生于一对h11/2中子的转动顺排.首次观察到100Nb(Z=41,N=59)的高自旋能级纲图和形变态,从而证实了100Nb中的形状共存,并确认,在Nb同位素链上,基态形状突变发生于N=58(球形)到N=59(大形变);而在Sr(Z=38),Y(Z=39)和Zr(Z=40)各同位素链上,基态形状突变均发生于N=59(球形)到N=60(大形变).100Nb具有大形变基态,同现有理论预言相矛盾,其大形变的基态及转动带所具有的很大的和不规则的转动惯量具有重要的理论意义. 对奇-质子Cs(Z=55)和La(Z=57)丰中子同位素八极激发的详细研究,发现了141,143,144Cs同位素链上电二极矩D.随中子数增加而减小的急剧变化,此前在145,147La中观察到的电二极矩Do的较缓和的减小似乎亦很陡地下延至148La.在Cs和La同位素中观察到的电二极矩D.的急剧下降很可能同偶-质子核146Ba和224Ra中观察到的电二极矩D.的急剧下降相类似,后者已获反射非对称平均场壳修正理论的成功解释.实验证明,141Cs具有很大电二极矩D.141Cs和142Xe中观测到的很大的电二极矩D.和仅在141Cs中观察到的电二极矩D.的simplex量子数相关性需要进一步的理论研究.根据转动频率比值ω-(I)/ω+(I)的检定,同Xe同位素一样,认定Cs同位素中包括号143Cs的八极激发为八极振动,而在La同位素中存在八极形变.

关键词: 形状过渡 , 轴对称形状 , 三轴形变 , 形状突变 , 带交叉 , 奇-质子 , 八极激发 , B(E1)/B(E2)比值 , 电二极矩D0 , 二极矩的下降 , 八极振动 , Cs,La同位素

Gammasphere上裂变丰中子核核结构若干前沿领域的新进展(Ⅰ:第一和第二部分)

罗亦孝 , J.H.Hamilton , J.O.Rasmussen , A.V.Ramayya , C.Goodin , A.V.Daniel , N.J.Stone , 朱胜江 , J.K.Hwang , 刘少华 , C.J.Beyer , 李科 , H.L.Crowell , D.Almehed , S.Frauendorf , A.Covello , V.Dimitrov , 张敬业 , 车兴来 , 姜卓 , D.Fong , A.Gelberg , I.Stefanescu , A.Gargano , E.F.Jones , P.M.Gore , I.Y.Lee , G.M.Ter-Akopian , Yu.Ts.Oganessian , M.A.Stoyer , R.Donangelo , 马文超 , J.D.Cole , J.Kormicki , 张学谦 , S.C.Wu , J.Gilat , T.N.Ginter , S.J.Asztalos

原子核物理评论

使用Gammasphere多探测器系统对252Cf裂变源瞬发γ射线进行γ-γ-γ和γ-γ(θ)符合测量,裂变丰中子原子核核结构若干前沿领域的深入研究获得了新的进展.高达5.7×1011以上的三重和更高重符合事件的数据统计,以及更少压缩的三维数据为宽广未知丰中子核区的寻找和研究提供了有利的条件.在具有重要物理意义的若干丰中子核区首次建立,或显著扩展了一批包括转晕态和转晕附近能态的高自旋能级纲图.在偶-偶丰中子核110,112Ru和108Mo中鉴别出了手征对称破缺结构.丰中子110,112Ru附近核的三轴形变基态具有最低的能量,在它们之中已确认了接近最大值的三轴形变.在这些Ru和Mo同位素中观察到的手征双线能带展示出手征破缺的一切特征,特别是其理想的能量简并,表明它们在迄今已报道的手征破缺结构中,具有最好的手征特性.研究了手征结构从具有γ软度的108Ru到具有大三轴形变的110,112Ru的过渡.斜轴推转(TAC)和随机相近似(RPA)理论计算成功地拟合了在这些偶-偶丰中子核中观察到的手征双线能带的特性,并指定其为软手征振动态.在这些偶-偶核中观察到的手征破缺不可能归纳为奇-奇核中那样的简化的几何图像.前者来自闭壳外所有中子的相互作用.对双幻核132Sn附近N=83同中素链的系统研究为这个极富吸引力的核区提供了大量新的谱学信息.N=83同中素135Te(Z=52),134I(Z=53),137Xe(Z=54),138Cs(Z=55)和139Ba(Z=56)的最新能级信息,特别是首次建立的138Cs高自旋能级纲图和壳模型理论计算表明,Z=50质子闭壳外少数g7/2价质子激发同N=82中子闭壳外之唯一F7/2价中子的耦合对该核区能级结构具有关键作用.观察到了132Sn和208Pb附近核区谱学信息的相似性和相对应的三粒子和五粒子态.在135Te中观察到了磁转动,这是在双幻核132Sn附近观察到的首例磁转动.

关键词: 丰中子核 , 高自旋 , 转晕态 , 裂变 , 252Cf , γ射线三重符合 , 角关联 , Gammas-phere多探测器系统 , 手征对称破缺 , 三轴形变 , 斜轴推转(TAC)计算 , 软手征振动 , N=83同中数链 , 双幻核132Sn , 壳模型计算 , 磁转动 , 谱学相似性

Energy levels of the d*(8) electron and d*(2) hole system

Physical Review B

In the investigation of the optical and magnetic properties of the semiconductors containing transition-metal ions, the one-electron orbital cannot be treated with a pure d orbital because of a strong covalence. This paper presents the energy matrix of the d*(8) and d*(2) (d* means a modified d function) system, in which the covalence is described by two covalent factors. The differences between the matrix diagonal elements of the t(2)(m)e(n) term of the d*(8) system and the t(2)(6-m)e(4-n) term of the d*(2) system vary with m and n. The d(N) electron system can be explained with the d(10-N) hole system because the difference between the energy matrix of the d(N) and d(10-N) systems has a fixed value. However, this kind of simple relation does not exist for the d*(N) and d*(10-N) systems when the covalence is considered. A numerical calculation shows that the variation of the energy levels with the covalence for Ni2+ in the d*(8) electron system is larger than that in the d*(2) hole system. The calculated energy levels obtained from the d*(8) matrix are in good agreement with the experimental data of the Ni2+ ion for ZnS:Ni and ZnSe:Ni. This suggests that the d*(8) electron system instead of the d*(2) hole system should be used in the investigation of optical and magnetic properties of semiconductor containing Ni2+ ions.

关键词: zns-ni;absorption;vanadium;impurities;spectra;ions

液晶材料与3D显示

张兴 , 郑成武 , 李宁 , 周兴丹 , 李正强 , 华瑞茂

液晶与显示 doi:10.3788/YJYXS20122704.0448

介绍了3D显示的基本原理,重点介绍了目前3D显示的主流技术类型,包含了眼镜式3D技术以及裸眼式3D技术,其中眼镜式3D技术包含色差式3D技术、偏光式3D技术和主动快门式3D技术;裸眼式3D技术包含视差屏障式3D技术、柱状透镜式3D技术、指向光源式3D技术和多层显示式3D技术.阐述了各种3D显示技术的基本实现原理和应用领域、并对涉及液晶显示的几种3D技术的优缺点进行了对比.结合液晶材料的特点与3D液晶显示的实际要求,阐述了3D液晶面板对液晶材料快速响应方面的要求,以及液晶透镜对液晶材料光学各向异性参数的要求.

关键词: 3D显示 , 眼镜式3D显示 , 裸眼式3D显示 , 液晶材料

COMPARISON OF FATIGUE AND CREEP BEHAVIOR BETWEEN 2D AND 3D-C／SiC COMPOSITES

D.Han , S.R.Qiao , M.Li , J.T.Hou , X.J.Wu

金属学报(英文版)

The differences of tension-tension fatigue and tensile creep characters of 2D-C/SiC and 3D-C/SiC composites have been scrutinized to meet the engineering needs. Experiments of tension-tension fatigue and tensile creep are carried out under vacuum high temperature condition. All of the high temperature fatigue curves are flat; the fatigue curves of the 2D-C/SiC are flatter and even parallel to the horizontal axis. While the tension-tension fatigue limit of the 3D-C/SiC is higher than that of the 2D-C/SiC, the fiber pullout length of the fatigue fracture surface of the 3D-C/SiC is longer than that of the 2D-C/SiC, and fracture morphology of the 3D-C/SiC is rougher, and pullout length of the fiber tows is longer. At the same time the 3D-C/SiC has higher tensile creep resistance. The tensile curve and the tensile creep curve of both materials consist of a series of flat step. These phenomena can be explained by the non-continuity of the damage.

关键词: 2D-C/SiC , null , null

Surface properties of 3d transition metals

Philosophical Magazine

Using the projector augmented wave method within density functional theory, we present a systematic study of the layer relaxation, surface energy and surface stress of 3d transition metals. Comparing the calculated trends for the surface energy and stress with those obtained for 4d and 5d metals we find that magnetism has a significant effect on the surface properties. Enhanced surface magnetic moments decrease the size of the surface relaxation, lower the surface energy and surface stress, leading to compressive stress in Cr and Mn.

关键词: surface relaxation;surface energy;surface stress;magnetic transition;metals;density functional theory;full charge-density;initio molecular-dynamics;total-energy;calculations;augmented-wave method;ab-initio;electronic-structure;atomic volume;work function;basis-set;relaxation

R&D STATUS ON INTERMETALLICS IN CHINA

CHEN Guoliang(State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 , China)SHI Changxu (Academia Sinica , Beijing 100864 , China)

金属学报(英文版)

This paper briefiy introduces the R&D of intermetallics in China. R&D on intermetallics in a national scale in China began near ten years ago. The investigation in past years focused on the fundamental research and materials development. A significant progress has been made. Various components that made of Ti3Al Ni3Al, TiAl and Fe3Al have been successfully manufactured Some of them have been evaluted. It is expected that some intermetallic alloys will be produced in an industrial scale in the near future.

关键词: :intermetallic alloys , null , null , null

R & D ACTIVITIES ON AEROSPACE MATERIALS IN KOREA

H.M. Kim(Korea Institute of Machinery and Materials , Korea Manuscript received 26 August 1996)

金属学报(英文版)

This paper briefly reviews research and development programs in Korean aerospace industry,with an emphasis on aircraft materials technology. International collaborations in these areas are outlined and the R & D activities are highlighted against the　background of the national economy.It is shown that the investment from government agencies and large enterprises has led to healthy development of aerospace materials industries in Korea.

关键词: :R & D , null , null , null

陶瓷3D打印技术综述

杨孟孟 , 罗旭东 , 谢志鹏

人工晶体学报

本文介绍了陶瓷3D打印技术目前的发展状况、主要的成型技术和重要的应用领域，重点介绍3D打印技术在陶瓷方向的应用。回顾了可适用于直接三维打印和立体光固化法打印的氧化物( Al2 O3、ZrO2)和非氧化物( Si3 N4、SiC)陶瓷浆料的最新研究成果及成型技术对制品性能的影响，并展望了陶瓷3D打印技术未来的发展方向。

关键词: 3D打印 , 陶瓷 , 浆料 , 成型技术

Size dependence of electrical resistivity 1D-layered nanostructures

Nanostructured Materials

The Landauer electrical resistivity R of one-dimensional (1D) layered nanostructures is calculated. The analysis of the logarithm of the resistance as a function of grain size reveals that there is a minimum value of resistivity R(min) when the grain size takes a value of d(c), where d(c) depends on the barrier height and excess volume of interface. R increases in the region of d(cl) > d > d(c), where d is the grain size, and d(cl) is another critical value of grain size. The mechanism of the anomalous resistivity behavior is discussed briefly.

关键词: nanocrystalline;resistance;alloys