The compounds Eu16Sb11 and Eu16Bi11 have been prepared from the elements in Ta containers by heating at 1100°C and then slowly cooled to 1000°C over 4 days. These compounds are isostructural with the Zintl-phase Ca16Sb11 and crystallize in the tetragonal space group P421m (Z=2). The structures were determined from single-crystal X-ray data (T=143 K) for Eu16Sb11 (a=12.674 (2) Å, c=11.720 (2) Å, R1=4.04% wR2= 10.84%), and Eu16Bi11 (a=12.885 (2) Å, c=11.883 (4) Å, R1=6.09%, wR2=15.24%). The Ca16Sb11 structure type can be described as pairs of face-shared square antiprisms that are joined by means of a square prism to form a columnar chain composed of Ca2+ cations and centered by Sb anions along the c axis. The columns are associated by means of Ca-Ca bonds that alternate long and short along the c axis in a ladder-like fashion. Along the a and b axes, there is an intergrowth of square prism, antiprism columns alternating with columns of face-sharing hexagonal antiprisms. The structures of these Eu compounds are compared with those of Ca16Sb11. Temperature-dependent resistivity of Eu16Sb11 indicates that it is a semiconductor. Magnetization measurements show that Eu16Sb11 and Eu16Bi11 are paramagnetic. The effective moment in the paramagnetic state for Eu16Sb11 is μ(exp)=32.2 (1) μ(B) per formula unit (8.06 (3) μ(B)/Eu atom) and for Eu16Bi11, μ(exp)=33.6 (2) μ(B)/formula unit (8.40) (6)μ(B)/Eu atom), consistent with divalent Eu2+ cations (μ(eff)=7.94 μ(B)/Eu atom). (C) 2000 Academic Press.
ASJC Scopus subject areas
- Inorganic Chemistry
- Physical and Theoretical Chemistry
- Materials Chemistry