Vmt. Thiede et W. Jeitschko, TERNARY INTERMETALLIC COMPOUNDS LNMN(2)AL(10) (LN = Y, LA-ND, SM, GD-DY) AND LNRE(2)AL(10) (LN = CE, PR, SM) WITH CACR2AL10-TYPE STRUCTURE, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 53(7), 1998, pp. 673-678
The twelve title compounds have been prepared for the first time. Thei
r CaCr2Al10-type structure (P 4/nmm, Z = 4) was refined from single-cr
ystal X-ray data for the three representatives TbMn2Al10 (a = 1274.3(2
) pm, c = 511.4(2) pm, R = 0.025 for 680 structure factors F and 43 va
riable parameters V), CeRe2Al10 (a = 1295.5(5) pm, c = 517.2(4)pm, R =
0.054 for 810 F and 46 V), and SmRe2Al10 (a = 1291.5(2) pm, c = 516.5
(l)pm, R = 0.021 for 622 F and 46 V). The atomic positions of the lant
hanoid and transition metal atoms are fully occupied. Significant devi
ations from the full occupancies were observed for two aluminum sites
in TbMn2Al10 and for all five aluminum sites of the two rhenium-contai
ning compounds, resulting in the compositions TbMn2Al9.63(2), CeRe2Al9
.52(8), and SInRe2Al9.16(9) The cell volume of CeRe2Al10 and to a smal
ler extent also that of CeMn2Al10 indicate mixed or intermediate +III/
+IV valencies of the cerium atoms in these compounds. The structural r
elationships between the three closely related body-centered tetragona
l structures of ThMn12, CeMn4Al8, DyFe6Al6, and the primitive tetragon
al structure of CaCr1Al10 are briefly discussed.