蔡晓红
,
卢荣春
,
曹柱荣
,
杨威
,
马新文
,
詹文龙
,
D.K.Torpokov
,
D.Nikolenko
原子核物理评论
doi:10.3969/j.issn.1007-4627.2002.02.054
兰州重离子加速器冷却储存环(HIRFL-CSR)的内靶系统, 是用于为实验环内的物理实验提供厚度为1011-1013 atoms/cm2的团簇靶和极化靶. 采用超声喷气技术获得团簇粒子束, 采用Stern-Gerlach方法获得极化氢束和极化氘束.
关键词:
重离子冷却储存环
,
内靶
,
团簇
,
极化原子束
雷雨
,
万怡灶
,
张宗强
,
王玉林
材料科学与工程学报
doi:10.3969/j.issn.1673-2812.2003.06.012
本文研究了纤维体积分数对三维编织芳纶纤维增强铸性尼龙(简称K3D/MCPA)复合材料力学性能的影响.研究表明,K3D/MCPA复合材料有优异的抗冲击性能,冲击强度比三维编织芳纶纤维增强铸性尼龙(简称C3D/MCPA)和纯基体均有大幅度的提高,且随着纤维体积的提高而升高.K3D/MCPA复合材料剪切强度随纤维体积比的增大而增大,其纵向剪切强度低于纯基体和C3D/MCPA复合材料,但其横向剪切强度高于它们.K3D/MCPA复合材料弯曲强度与弯曲模量随纤维体积比的提高而提高,但与相同体积比的C3D/MCPA相比,K3D/MCPA的弯曲强度与弯曲模量均较低.
关键词:
纤维体积分数
,
三维编织芳纶纤维
,
铸型尼龙
,
力学性能
朱杰武
,
柳永宁
,
许雁
,
冯耀荣
机械工程材料
doi:10.3969/j.issn.1000-3738.2005.06.007
在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.
关键词:
管线钢
,
断裂韧度
,
止裂韧度
,
韧-脆断裂转变
金亚旭
,
田玉明
,
闫时建
,
华林
稀有金属材料与工程
采用液态金属搅拌铸造法制备了K2Ti6O13晶须(PTW)增强AZ91D镁基复合材料,采用动电位极化测试和静态腐蚀试验测试了复合材料的耐腐蚀性能,并利用SEM对复合材料的表面形貌进行了观察和分析.结果表明:PTW对合金铸态组织具有明显的细化作用,而且共晶组织形貌发生明显改变,由完全离异共晶骨骼状的β相转变为部分离异共晶的蜂窝状β相.合金显微组织的细化及β相体积分数的降低,抑制了微电偶腐蚀的破坏作用,提高了AZ91D镁合金的耐蚀性能.
关键词:
搅拌铸造
,
镁基复合材料
,
晶须
,
腐蚀
Materials Letters
Single crystals of K-doped blue bronze Rb0.15K0.15MoO3 and Rb0.3MoO3 have been investigated by measurements of the X-ray photoemission spectrum (XPS), electrical resistivity and thermoelectric power, respectively. Analysis of the XPS data reveals that two final states representing alternate screening channels coexist in Rb0.15K0.15MoO3. Compared with the pure bronze, the Mo sites of the doped sample contain less 4d electrons which reflected in the movement of Mo3d spectrum. Due to the discrepancy of electronic structure, the K ion doping results in the notable increase of the single particle activation energy and decrease of the thermoelectric power in the charge density wave state. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
blue bronze;charge-density-wave;electronic structure;nonlinear transport;k0.30moo3;tl0.3moo3;k0.3moo3;moo3
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
Physical Review B
Three-dimensional (3D) Dirac point, where two Weyl points overlap in momentum space, is usually unstable and hard to realize. Here we show, based on the first-principles calculations and effective model analysis, that crystalline A(3)Bi (A = Na, K, Rb) are Dirac semimetals with bulk 3D Dirac points protected by crystal symmetry. They possess nontrivial Fermi arcs on the surfaces and can be driven into various topologically distinct phases by explicit breaking of symmetries. Giant diamagnetism, linear quantum magnetoresistance, and quantum spin Hall effect will be expected for such compounds.
关键词:
electronic-structure;insulator;surface;bi2te3;cone;hall
