T. Hufken et W. Jeitschko, THE HIGH-TEMPERATURE (BETA) MODIFICATION OF Y4C7 WITH LU4C7 TYPE AND DY3C4 WITH SC3C4 TYPE-STRUCTURE, Journal of alloys and compounds, 278(1-2), 1998, pp. 161-164
A new modification of Y4C7 has been prepared by are-melting of the ele
mental components and subsequent annealing at 1300 degrees C. Its crys
tal structure was refined from X-ray powder diffractometer data: P2(1)
/c, a=372.6(1) pm, b=1369.2(2) pm, c=652.7(1) pm, P=103.03(1)degrees,
Z=2, R=0.027 for 341 structure factors and 15 positional parameters. T
he C-C distances in the propadienyl anion are 125(3) and 132(3) pm in
good agreement with the average C-C distance of 132 pm found in the st
ructures of the carbides beta-Ho4C7 and Lu4C7. The new carbide Dy3C4 h
as a tetragonal Sc3C4 type structure with the lattice constants a=808.
3(1) pm and c=1588.1(3) pm. (C) 1998 Elsevier Science S.A. All rights
reserved.