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제108회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Structural Comparison of Y5-xMg24+x (1.07(1) ≤ x ≤ 1.30(1)) and its derivative Y0.65(2)Ce0.35Mg4.72

2011년 8월 2일 10시 43분 17초
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금 <발표Ⅳ>
저자 및
정야호, Gordon J. Miller1, 유태수
충북대학교 화학과, Korea
1Department of Chemistry, Iowa State University, Ames, IA 50011, USA, United States
A series of Y5-xMg24+x compounds and its derivative, Y0.65(2)Ce0.35Mg4.72, were synthesized using high temperature, solid-state methods and characterized by both powder and single crystal X-ray diffraction. The Y5-xMg24+x series crystallizes in the cubic α-type structure (space group I-43m , Z = 2, Pearson symbol cI58) with the mixed-occupancy of Y and Mg at the 8c site, whereas Y0.65(2)Ce0.35Mg4.72 adopts the cubic GdMg5-type structure (space group F-43m , Z = 8, Pearson symbol cF440), which can be described as a defected Sm11Cd45-type structure. All of the compounds were analyzed by single crystal X-ray diffraction: Y3.93(1)Mg25.07, Y3.82(1)Mg25.18, Y3.73(1)Mg25.27, Y3.70(1)Mg25.30, and Y6.29(2)Ce3.36Mg45.53. As the smaller Mg atoms progressively replace Y atoms at the 8c site in Y5-xMg24+x, the phase width was observed in the range of Y3.93(1)Mg25.07 - Y3.70(1)Mg25.30 with the decrease of lattice parameter a (11.2337(6) ≤ a ≤ 11.260(1)Å). Y0.65(2)Ce0.35Mg4.72 forms a 2 × 2 × 2 superstructure of the body-centered cubic W which can be described as a quaternary version of NaTl. Partial occupancy of 89(3) % was observed only at the inner tetrahedron site in the A unit. The mixed occupancy of Y, Ce or Mg was observed at the center and the cubo-octahedron site of the A unit, at the center of the B unit and the outer tetrahedron of the D unit.