Positron annihilation studies of icosahedral quasicrystals and their approximants in the Al?Cu?Ru?(Si) alloy systems
Positron annihilation studies of icosahedral quasicrystals and their approximants in the Al?Cu?Ru?(Si) alloy systems
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Al?Cu?Ru?(Si)合金系二十面体准晶及其近似体的正电子湮没研究
DOI：
10.1088/0953-8984/16/10/020
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
K. Kimura
中科院分区：
文献类型：
--
作者：
H. Uchiyama;T. Takahashi;K. Arinuma;Koichi Sato;I. Kanazawa;E. Hamada;Toshikazu Suzuki;K. Kirihara;K. Kimura
二十面体准晶Al_（62.4）Cu_（25.4）Ru_（12.2）及其立方准晶的正电子寿命（1/ 1-Al58Cu31.5Ru10.5，1/ 1-Al 68 Cu 7 Ru 17 Si 8，和10-Al 55 Cu 15 Ru 20 Si 10），二十面体准晶Al62.4Cu25.4Ru12.2和它的1/ 1-Al 68 Cu 7 Ru 17 Si 8立方近似物的双探测器符合多普勒展宽，用慢正电子束测量了1/ 1-Al_（58）Cu_（31.5）Ru_（10.5）立方近似体的多普勒展宽。结构上固有的捕获网站引起的饱和捕获检测寿命测量。用符合多普勒展宽技术确定了二十面体准晶Al_（62.4）Cu_（25.4）Ru_（12.2）和1/ 1-Al_（68）Cu_（17）Si_（18）立方准晶中陷阱位的化学环境主要是被Al原子包围。用慢正电子束测量了1/ 1-Al_（58）Cu_（31.5）Ru_（10.5）立方近似体中的S参数，由此导出正电子在该近似体中的扩散长度为？这显然太短，可能是由于如上所述的高浓度的捕获位点。二十面体准晶Al 62.4Cu 25.4Ru 12.2及其各种近似的原子结构进行了讨论，并与目前提出的模型。
The positron lifetimes for the icosahedral quasicrystal Al62.4Cu25.4Ru12.2 and its cubic approximants (1/ 1-Al58Cu31.5Ru10.5, 1/ 1-Al68Cu7Ru17Si8, and 1/0-Al55Cu15Ru20Si10), two-detector coincident Doppler broadening for the icosahedral quasicrystal Al62.4Cu25.4Ru12.2 and its 1/ 1-Al68Cu7Ru17Si8 cubic approximant, and the Doppler broadening obtained by making use of a slow positron beam for the 1/ 1-Al58Cu31.5Ru10.5 cubic approximant have been measured. Structurally intrinsic trapping sites giving rise to saturation trapping were detected by lifetime measurements. The chemical environments of the trapping sites in the icosahedral quasicrystal Al62.4Cu25.4Ru12.2 and the 1/ 1-Al68Cu7Ru17Si8 cubic approximant were determined by coincident Doppler broadening techniques to be dominantly surrounded by Al atoms. The positron diffusion length in the 1/ 1-Al58Cu31.5Ru10.5 cubic approximant derived from the measured S parameter measured by means of a slow positron beam was ??, which is clearly too short, probably due to the high concentration of trapping sites as described above. The atomic structures of the icosahedral quasicrystal Al62.4Cu25.4Ru12.2 and its variety of approximants are discussed and compared to the present proposed model.