...
首页> 外文期刊>Physical review >Anomalous vibrational dynamics in the Mg_2Zn_11 phase
【24h】

Anomalous vibrational dynamics in the Mg_2Zn_11 phase

机译:Mg_2Zn_11相的异常振动动力学

获取原文
获取原文并翻译 | 示例
           

摘要

We present a combined experimental and theoretical study of the structure and the lattice dynamics in the complex metallic alloy Mg_2Zn_(11), by means of neutron and x-ray scattering, as well as ab initio and empirical potential calculations. Mg_2Zn_(11) can be seen as an intermediate step in structural complexity between the simple Laves-phase Mg_2Zn_2 on one side, and the complex 1/1 approximants and quasicrystals ZnMgAl and Zn(Mg)Sc on the other. The structure can be described as a cubic packing of a triacontahedron whose center is partially occupied by a Zn atom. This partially occupied site turned out to play a major role in understanding the lattice dynamics. Data from inelastic neutron scattering evidence a Van Hove singularity in the vibrational spectrum of Mg_2Zn_(11) for an energy as low as 4.5 meV, which is a unique feature for a nearly-close-packed metallic alloy. This corresponds to a gap opening at the Brillouin zone boundary and an interaction between a low-lying optical branch and an acoustic one, as could be deduced from the dispersion relation measured by inelastic x-ray scattering. Second, the measured phonon density of states exhibits many maxima, indicating strong mode interactions across the whole energy range. The origin of the low-energy modes in Mg_2Zn_(11) and other features of the vibrational spectra are studied, using both ab initio and empirical potential calculations. A detailed analysis of vibrational eigenmodes is presented, linking features in the vibrational spectrum to atomic motions within structural building blocks.
机译:我们通过中子和X射线散射以及从头算和经验势计算的方法,对复合金属合金Mg_2Zn_(11)的结构和晶格动力学进行了组合的实验和理论研究。 Mg_2Zn_(11)可以看作是一侧简单的Laves相Mg_2Zn_2与另一侧的复杂1/1近似物和准晶体ZnMgAl和Zn(Mg)Sc之间结构复杂性的中间步骤。该结构可以描述为三面体的立方堆积,其中心部分被Zn原子占据。事实证明,该部分占据的位置在理解晶格动力学方面起着重要作用。来自非弹性中子散射的数据证明,对于低至4.5 meV的能量,Mg_2Zn_(11)振动谱中的Van Hove奇异性是几乎密排的金属合金的独特特征。这对应于在布里渊区边界处的间隙开口以及低处的光学分支与声学分支之间的相互作用,这可以从通过非弹性x射线散射测量的色散关系推导出来。其次,所测得的状态声子密度表现出很多最大值,表明在整个能量范围内强模式相互作用。利用从头算和经验势计算,研究了Mg_2Zn_(11)中低能模式的起源以及振动光谱的其他特征。给出了振动本征模态的详细分析,将振动谱中的特征与结构构件内的原子运动联系起来。

著录项

  • 来源
    《Physical review》 |2011年第14期|p.144202.1-144202.17|共17页
  • 作者单位

    lnstitutfuer Theoretische und Angewandte Physik (HAP), Universitdt Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany,lnstitutfuer Theoretische und Angewandte Physik (HAP), Universitdt Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany;

    Institute of Physics, Slovak Academy of Sciences, 84511 Bratislava, Slovakia;

    Fakultat fuer Mathematik, Universitdt Bielefeld, 33501 Bielefeld, Germany;

    Institut Laue-Langevin, Grenoble, France;

    Institut Laue-Langevin, Grenoble, France;

    Institut Laue-Langevin, Grenoble, France;

    Institut Laue-Langevin, Grenoble, France;

    European Synchrotron Radiation Facility, Grenoble, France;

    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan;

    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan;

    Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden;

    Department of Materials Chemistry, Uppsala University, SE-751 21 Uppsala, Sweden;

    Institut fuer Festkbrperphysik, TU Wien, Wiedner Hauptstrasse 8-10,1040 Wien, Austria;

    Institut fuer Festkbrperphysik, TU Wien, Wiedner Hauptstrasse 8-10,1040 Wien, Austria;

    lnstitutfuer Theoretische und Angewandte Physik (HAP), Universitdt Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    alloys;

    机译:合金;

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号