Study on mesoscopic physical phenomenon in many particle systems by electron holography

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1) We determined site occupancy of Zn atoms in (Al, Zn)_<49>Mg_<32>-type Mg_<40>Al_<60-x>Zn_x (x=14=51) alloys by single crystal X-ray diffractometry. We also demonstrated that they have no atom at the center of Bergman-type atom cluster, on the contrary to the previously proposed models.2) We succeeded in fabricating a single crystal of 2/1 cubic approximant, which were found in (Al, Zn)-Mg alloys, and determined sophisticated structure of Bergman clusters by X-ray diffractometry.3)Single crystal diffractometry allowed us to determine the structure of the following 1/0 crystalline approximants : Al_<66.8>Pd_<21.2>Ru_<12.0> (Fms ; a=1.56058nm), Al_<63.6>Pd_<30.2>Fe_<6.2> (Fms ; a=1.55187nm), and Al_<68.9>Pd_<17.1>Fe_<13.9> (Fms ; a=1.53755nm). Surrounding the 1/4, 1/4, 1/4 position, Al assumes icosahedral coordination, which were also surrounded by pentagonally-coordinated clusters that share edges and forms a simple cubic arrangement.4) We showed, using single crystal X-ray diffractometry, that Al_<57.3>Cu_<31.4>Ru_<11.3> 1/1 crystalline approximant belongs to the cubic system with Pm3 and a=1.23773, in which truncated dodecahedron clusters arrange themselves in a cubic manner, sharing octahedrons.5)We also showed that 1/0, 1/1, 2/1 crystalline approximants are grouped into the simple cubic and body-centered cubic systems when viewed via arrangements of icosahedral atom clusters.