VM.Kuznetsov
,
R.I.Kadyrov and G.E.Rudenskii (Institute of Strength Physics and Material Science
,
Russian Academy of Sciences
,
Siberian Branch.Academicheskii av. 2/1
,
634048 Tomsk
,
Russia)
材料科学技术（英文）
The surface energy values of (100), (110), (111) surfaces in Ni. Al and ordered alloys NiAl and Ni3Al have been calculated within the framework of methodology based upon the electron density functional method. The results of calculations are in good agreement with the known for pure metals experimental data and in case of Ni3Al allop There is also a good agreement with the results obtained by calculation using the embedded atom method. The investigation has been carried out in this work to show that the surface energy σ of alloys can not be interpreted as an averaged concentration σ of pure metals. For NiAl, the obtained resulsts reveal considerable distinctions in anisotropy of a in comparison to the anisotropy of surface energy in pure matals.
关键词:
Journal of Physics and Chemistry of Solids
A new theory of spectral thermal shifts (TS) has been developed. For the first time, by taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI), all the levels and the admixtures of wavefunctions within d(3) electronic configuration, the microscopic expressions for all the parameters in Raman, neighbor-level and optical-branch terms of TS due to EPI have been derived; their values for the R-1, R-2 and ground levels of ruby have been evaluated; the contributions to TS from thermal expansion have also been calculated; and then, the unified calculation of the TS of R-1 and R-2 lines and zero-field splitting (ZFS) for the ground state and the thermal broadenings of R, R' and B line-groups have successfully been accomplished. It is found that the contributions from the second-order term of EPI Hamiltonian H-(2) are dominant in Raman terms of R-1 and R-2 lines; the optical-branch terms play an important role in TS and increase rapidly with temperature and the ones of R-1 and R-2 lines have opposite signs due to the effects of neighbor levels; the neighbor-level terms are very important and it is the admixtures of wavefunctions caused by Coulomb interaction between d electrons and/or trigonal-field and/or spin-orbit interactions that make them nonzero; the contributions to TS from thermal expansion are also important. (C) 2000 Elsevier Science Ltd. All rights reserved.
关键词:
crystal fields;optical properties;phonons;electronic structure;thermal expansion;diamond-anvil cell;entire energy-spectrum;r-line;pressure;measurement;temperature;spectroscopy;calibration;dependence
Communications in Theoretical Physics
For the first time, by taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of wavefunctions within d(3) electronic configuration, the values of parameters in expressions of Raman and optical-branch terms of thermal shifts (TS) due to EPI for three levels, T-4(2) band and T-4(1) band of ruby have been evaluated; the contributions to TS of T-4(2) and T-4(1) broad bands from thermal expansion have also been. calculated; and then, the TS of the peak energies of 'T2 and 4 Ti broad bands have been calculated. The results are in satisfactory agreement with observed data. The values of single-electron reduced matrix elements representing the strengths of EPI of T-4(2) and T-4(1) bands have respectively been determined. For TS of the peak energies of T-4(2) and T-4(1) bands, it is found that the contribution to TS from the second-order term in EPI Hamiltonian is dominant; TS due to EPI of acoustic branches are over two times as much as those of optical branches, and both of them increase rapidly with temperature; the neighbor-level term is insignificant; the contribution to TS from thermal expansion is specially important, and all the three terms of TS of T-4(2) or T-4(1) band axe red shifts.
关键词:
crystal fields;optical spectral bands;electron-phonon interaction;thermal expansion;thermal shift;theoretical calculations;high-pressure;field;spectroscopy;spectra
云月厚
,
李国栋
稀土
doi:10.3969/j.issn.1004-0277.2011.02.008
采用溶胶-凝胶法制备了钙钛矿型锰氧化物(La1-x Cex)2/3Sr1/3 MnO3(x=0.1,0.3,0.5)超微粉末,用XRD分析了该材料的相结构,并用AV3618型微波矢量网络分析仪测试了样品在8.2GHz～12.5GHz范围内的微波吸收特性.结果表明,样品在1000℃焙烧后出现单一的钙钛矿型结构,当材料涂层厚度为1mm、x=0.3时,(La1-x Cex)2/3 Sr1/3 MnO3的吸波性能最佳.在测试频段内有三个吸收峰,最高的吸收峰在9.1GHz处,峰值高达36.8dB,并且吸收衰减量大于18dB的频带宽度达2.2GHz.
关键词:
溶胶-凝胶法
,
钙钛矿型锰氧化物
,
吸波特性
吴崇试
,
潘奕
原子核物理评论
doi:10.3969/j.issn.1007-4627.2002.01.001
系统分析了A≈170区正常形变带[521]1/2-中的ΔI=1颤动现象. 根据旋称伙伴带的跃迁能量提取Δ2 Eγ (I)=[Eγ(I)+Eγ(I-2)]/2-Eγ(I-1)值, 表现出旋称相关的规则上下颤动. 其颤动幅度在低自旋端约为50 keV, 而后随自旋而增大或减小, 大体呈抛物线形. 利用改进的ab公式, 提取了相关的脱耦合系数. 运用Nilsson波函数, 探讨了原子核集体哈密顿量中高阶微扰项的可能形式.
关键词:
正常形变带
,
旋称伙伴带
,
ΔI = 1颤动
,
脱耦合效应
,
改进的ab拟合
Chinese Physics Letters
The magnetic properties of 1 T-TaS2 and 1 T-Fe-0.07 Ta-0.93 S-2 have been studied, Experimental results show that the phase transition temperature of 1 T-TaS2 is a function of the magnetic field, At low temperatures, both compounds are in a mixed state of charge density wave -spin density wave due to the coherent superposition of antiferromagnetic coupling.
关键词:
density
季路成
工程热物理学报
为理清1+1/2对转涡轮及1+3/2对转涡轮使用范围和效能,从而帮助设计决策,本文采用Stewart方法,从速度三角形基本分析入手,以速功比为主要变量,考察、对比1+3/2和1+1/2对转涡轮性能特点.研究表明:各转速比下,1+3/2对转涡轮高效率范围都比1+1/2对转涡轮窄,但其高效区发生在更小的总速功比区域;随转速比绝对值增加,两种涡轮高效率区都增加,高效率区位置都偏向大的总速功比区域;相比于1+1/2对转涡轮,1+3/2对转涡轮具有较低出功比,且偏向于低速功比区域;随转速比绝对值增加,两种对转涡轮出功比范围均拓展.这些结果为未来先进航空发动机涡轮选型提供了重要借鉴.
关键词:
航空发动机
,
对转涡轮
,
无导叶对转涡轮
,
效率
,
出功比
张昌
,
段远源
,
史琳
,
朱明善
,
韩礼钟
工程热物理学报
析了气相声速与理想气体比定压热容的热力学关系，用超声变程干涉仪测定了1,1,1,2,3,3,3-七氟丙烷(HFC-227ea)的72组气相声速值，温度范围273-333 K，压力范围26-315 kPa，测量不确定度小于0.05%。根据这些实验数据，确定了HFC-227ea的理想气体比定压热容和声速第二维里系数，并分别拟合得到了与温度的函数，理想气体比定压热容的不确定度小于0.5%。使用方阱势能模型导出了HFC-227ea的第二维里系数，并与文献值进行了比较。
关键词:
HFC-227ea
,
声速
,
理想气体比定压热容
,
第二维里系数
