Showing papers by "Jiang-Gao Mao published in 2001"
TL;DR: Two new Zintl phases Ae (2)LiInGe(2) (Ae = Ca 1; Sr 2) were obtained from stoichiometric reactions of the pure elements in sealed Nb tubing at 1000-1050 degrees C.
Abstract: Two new Zintl phases Ae2LiInGe2 (Ae = Ca 1; Sr 2) were obtained from stoichiometric reactions of the pure elements in sealed Nb tubing at 1000−1050 °C. The isomorphous polar intermetallic phases crystallize in the orthorhombic space group Pnma, with cell constants of a = 7.2512(7), b = 4.4380(5), and c = 16.902(1) A for compound 1, and a = 7.5033(8), b = 4.6194(5), and c = 17.473(2) A for compound 2. The crystal structure can be derived from the vertex-sharing of InGe4/2 tetrahedral units that form “corrugated” sheets normal to the crystallographic c-axis. Calcium and lithium atoms act as “spacers” that effectively separate the anionic [InGe2]5- layers. The layered anionic substructure is similar to those exhibited by layered metal oxides, sulfides, and silicates. The connectivity of the tetrahedral building unit, [InGe4/2]5-, is analogous and isoelectronic to the silicate [SiO4/2] unit.
21 citations
TL;DR: In this paper, a ternary phase La11In6Ge4 was obtained from high temperature reactions of the pure elements in welded Ta tubes, and its crystal structure was established by single-crystal X-ray diffraction in the tetragonal space group I4/mmm (No. 139).
20 citations
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TL;DR: In this paper, a ternary phase La11In6Ge4 was obtained from high temperature reactions of the pure elements in welded Ta tubes, and its crystal structure was established by single-crystal X-ray diffraction in the tetragonal space group I4/mmm (No. 139).
Abstract: The new tetragonal phase La11In6Ge4 is obtained from high temperature reactions of the pure elements in welded Ta tubes. Its crystal structure was established by single-crystal X-ray diffraction in the tetragonal space group I4/mmm (No. 139), with cell parameters of a=12.073(2), and c=16.829(3) A. The structure of La11In6Ge4 may be derived from the Ho11Ge10 structure type by replacing Ge atoms of the Ge4 squares and Ge2 dimers in Ho11Ge10 with indium. However, the nominal squares and dimers in Ho11Ge10 are no longer isolated fragments in La11In6Ge4, but are linked via In–In bonds (3.222(3) A), resulting in a three-dimensional In anionic network. The chemical bonding of the new ternary phase can be formulated according to the Zintl concept as La11)33+ Ge4isolated)16− In6network)17−. Extended-Huckel band structure calculations on the [In6]17− network indicate that the compound may be considered a ‘metallic’ Zintl phase with the valence bands having an electronic count associated with an electron-precise [In6]14− network of In4 squares and In2 units. The remaining electrons occupy conduction bands that represent anti-bonding interactions within the In2 fragments, and between the In squares and dimers.