The Crystal Data of Ternary Rare Earth Borides, RCo<SUB>2</SUB>B<SUB>2</SUB>
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概要
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Compounds with the composition of RCo<SUB>2</SUB>B<SUB>2</SUB> (R=La, Nd, Sm, Gd, Tb, Dy, and Y) were prepared by arcmelting methods. Their crystal structure was investigated by means of X-ray diffraction. These ternary rare earth borides crystallize in the tetragonal lattice. The lattice parameters are <I>a</I>=3.616±0.003 Å and <I>c</I>=10.215±0.005 Å for LaCo<SUB>2</SUB>B<SUB>2</SUB> and <I>a</I>=3.561±0.002 Å and <I>c</I>=9.358±0.005 Å for YCo<SUB>2</SUB>B<SUB>2</SUB>. The good agreement between the X-ray diffraction intensities observed and those calculated shows that the ternary borides, LaCo<SUB>2</SUB>B<SUB>2</SUB> and YCo<SUB>2</SUB>-B<SUB>2</SUB>, crystallize in the ThCr<SUB>2</SUB>Si<SUB>2</SUB>-type structure. The crystallographic data obtained for LaCo<SUB>2</SUB>B<SUB>2</SUB> and YCo<SUB>2</SUB>B<SUB>2</SUB> are as follows: space group 14/mmm(D<SUB>4h</SUB><SUP>17</SUP>); 2R in 2(a), 4Co in 4(d), and 4B in 4(e) with <I>z</I>∼3⁄8. The boron atoms in this structure are situated at the center of a trigonal prism formed by four rare earth atoms and two cobalt atoms. We also found the RCo<SUB>2</SUB>B<SUB>2</SUB> compounds to be isostructural with LaCo<SUB>2</SUB>B<SUB>2</SUB> and YCo<SUB>2</SUB>B<SUB>2</SUB>, where R=Nd, Sm, Gd, Tb, and Dy. However, efforts to prepare CeCo<SUB>2</SUB>B<SUB>2</SUB> and ErCo<SUB>2</SUB>B<SUB>2</SUB> by arc-melting were unsuccessful.
- 公益社団法人 日本化学会の論文
著者
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Niihara Koichi
The Research Institute For Iron Steel And Other Metals
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Yajima Seishi
The Research Institute For Iron Steel And Other Metals
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Shishido Toetu
The Research Institute For Iron Steel And Other Metals
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