材料期刊网

掺杂原子质量对硅声子散射的影响

周敏 , 姚曼 , 陈序良 , Simon R.Phillpot

材料科学与工程学报

本文采用分子动力学方法,重点研究了掺杂原子质量对硅晶格振动行为的影响,在原子尺度上清楚地展示出目前实际无法展现的点缺陷影响声子散射的演化过程.结果表明:同位素掺杂的存在会在特定声子频率区引起共振,使透射率显著减少,掺杂原子质量较大时共振区域明显扩大,且透射率随掺杂浓度增加下降得越快,会使材料导热性变差;掺杂原子质量相同时,共振区中最小透射率对应的频率值不随浓度变化而改变.在大于共振频率时,有明显LA到TA声子模式的转变,随掺杂原子质量的增加TA模式所占比例增大.这些结果对深入认识点缺陷对晶格导热微观机制的影响有积极意义.

关键词: 掺杂 , 声子散射 , 分子动力学模拟 , 原子质量

hcp-Ti中辐照诱发缺陷演化及温度效应的分子动力学研究

姚曼 , 高晓 , 曾维鹏 , 王旭东 , 徐海譞 , Simon R.Phillpot

金属学报 doi:10.3724/SP.J.1037.2013.00007

运用分子动力学方法研究了hcp-Ti中的级联碰撞.建立晶体结构模型,选取不同的初级碰撞原子方向和能量,分别研究了级联碰撞中所产生的点缺陷的演化情况,给出初始物理图景.对级联碰撞中的两大特征分布“离位峰”及“热峰”进行分析,定量讨论了损伤区瞬态温度分布,局部“熔化区域”的变化,辐照诱发峰值缺陷数和稳定缺陷数等,为分析材料辐照损伤行为提供了数据.本工作中运用的计算方法可作为研究材料辐照诱发缺陷形成微观机制的一个有效手段.

关键词: hcp-Ti , 级联碰撞 , 分子动力学 , 辐照诱发缺陷 , 温度

注氮剂量对SIMON材料性能影响的研究

张恩霞 , 孙佳胤 , 易万兵 , 陈静 , 金波 , 陈猛 , 张正选 , 张国强 , 王曦

功能材料与器件学报 doi:10.3969/j.issn.1007-4252.2004.04.008

采用氧氮共注的方法制备了氮氧共注隔离 SOI (SIMON) 圆片,对制备的样品进行了二次离 子质谱和透射电镜分析,并对埋层结构与抗辐射性能的机理进行了分析.结果表明,注氮剂量较低 时埋层质量较好.机理分析结果表明,圆片的抗辐照性能与埋层质量之间存在很密切的关系,埋层 的绝缘性能是影响器件抗辐射效应的关键因素.

关键词: 氧氮共注 , 氮氧共注隔离 , SIMON , SOI , 注入剂量

烧成制度对合成β-SiAlON-15R复相材料的影响

孟玉杰 , 王文武 , 吴吉光 , 曹会彦

耐火材料 doi:10.3969/j.issn.1001-1935.2011.04.007

以硅粉、金属铝粉、氧化铝微粉为主要原料,在氮气气氛中分别于1 500、1 550和1 600℃合成β-SiAlON(Z=2.5)和15R(Z =3)含量各为50％(w)的3-SiAlON-15R复相材料.利用TG-DSC和XRD研究了烧成制度对合成β-SiAlON-15R复相材料的影响.结果表明:(1)在500～550℃缓慢升温,850、1 080和1 300℃保温,有利于铝和硅氮化形成足够的氮化铝和氮化硅网络,抑制金属熔体的析出.(2)随着烧成温度的升高,合成材料中β-SiMON相含量降低,15R相含量增加,残余Al2O3减少.

关键词: 烧成制度 , 15R( SiAlON多型体) , β-SiAlON , 复相材料 , 合成

R-line thermal shift and thermal broadenings of R, R' and B lines for ruby

Communications in Theoretical Physics

The unified theoretical calculation of thermal shifts (TS) of R-1 and R-2 lines and thermal broadenings (TB) of R, R' and B lines for ruby was carried out for the first time. The calculated results are in very good agreement with a great number of experimental data. Especially by using quantum theory and taking into account all the admixtures of wavefunctions within d(3) electronic configuration, all the Gamma M in electron-phonon interaction (EPI), the electronic energy spectrum and lattice-vibration Spectrum, the very important contributions to TS and TB from single-phonon direct process were theoretically calculated in detail. The microscopic essentials of various contributions are revealed, and the mistakes in previous work are remedied.

关键词: diamond anvil cell;pressure measurement;spectroscopy;temperatures

Theoretical calculations of thermal broadenings and transition probabilities of R, R ' and B line-groups for ruby

Communications in Theoretical Physics

On the basis of the unified calculation of the thermal shifts of R-1 line, R-2 line and ground-state-splitting as well as the thermal broadenings of R, R' and B line-groups for ruby, by taking into account all the levels and admixtures of wavefunctions within d(3) electronic configuration and all the GammaM in electron-phonon interaction, the transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings, of R, R' and B line-groups have successfully been interpreted in terms of the direct and Raman processes of acoustic phonons. The theoretically predicted transition probabilities are in good agreement with the experimental ones.

关键词: crystal fields;electron-phonon interaction;thermal broadening;transition probability;direct and Raman processes;shifts

Phase diagram of R-Fe-Co pseudoternary system with R <= 33.3% (mole fraction, R = Sm0.5Dy0.5)

Transactions of Nonferrous Metals Society of China

Phase equilibria of the R-Fe-Co pseudoternary system with R less than or equal to 33.3% ( mole fraction, R = Sm0.5Dy0.5) were determined in an isothermal section at 1073 K and a vertical section of RFe2-RCo2 by using OM, X-ray diffractometer, EP-MA DTA techniques. There are seven intermetallic phases: (Sm, Dy) (Fe, Co)(2), (Sm, Dy) (Fe, Co)(3), (Sm, Dy)(6) (Fe, Co)(23), (Sm, Dy)(2) (Fe, Co)(7), (Sm, Dy) (Fe, Co)(5), Th2Ni17-type and Th2Zn17-type (Sm, Dy)(2)(Fe, Co)(17). The (Sm, Dy)(6)(Fe, Co)(23) phase dissolves 36% Co(mole fraction) at 1073 K. However, the (Sm, Dy)(2)(Fe, Co)(7) phase in R-2(Fe1-xCox)(7) alloys dissolves about 19% Fe(mole fraction) at 1073 K.

关键词: rare earth-iron-cobalt;phase diagram;structure;compounds;sm-co;magnetic-properties;binary-system;magnetostriction

NEUTRON DIFFRACTION STUDY ON R_2Fel_(17)N_x(R=Y,Dy,Nd)

YANG Jilian ZHANC Baisheng DINC Yongfan China Institute of Atomic Engergy , Beijing , ChinaYANG Yingchang ZHANG Xiaodong Peking University , Beijing , ChinaPAN Shuming General Research Institute for Non-Ferrous Metals , Beijing , China associate professor , P.O.Box 275 , Branch No.30 , Beijing 102413 , China

金属学报(英文版)

The N occupying sites and magnetic structures in R_2Fe_(17)N_x(R=Y,Dy,Nd)are de- termined by neutron diffraction.The effects of the site occupation of N on magnetic properties are discussed primarily.

关键词: neutron diffraction , null , null , null , null , null

SPIN REORIENTATION AND EXCHANGE INTERACTIONS IN (ND, R)2FE14B (R = Y, GD)

Journal of Magnetism and Magnetic Materials

Exchange fields in both (Nd, Y)2Fe14B and (Nd, Gd)2Fe14B series are determined by analyzing spin reorientation. Results calculated for the two systems suggest that the R-R exchange interactions between R ions are comparable with the crystal-field interaction and that their effect might be taken into account for reproducing the spin-reorientation temperature.

关键词: magnetization process;crystal;nd2fe14b;r2fe14b;transition

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