Syntheses, Structures, and Physical Properties of LnAsTe (Ln = La, Pr, Sm, Gd, Dy, Er)

Six rare-earth arsenic tellurides have been synthesized by the reactions of the rare-earth elements (Ln) with As
and Te at 1123 K. LaAsTe (a = 7.8354(11) Å, b = 4.1721(6) Å, c = 10.2985(14) Å, T = 153 K), PrAsTe (a =
7.728(2) Å, b = 4.1200(11) Å, c = 10.137(3) Å, T = 153 K), SmAsTe (a = 7.6180(16) Å, b = 4.0821(9) Å, c
= 9.991(2) Å, T = 153 K), GdAsTe (a = 7.5611(15) Å, b = 4.0510(8) Å, c = 9.920(2) Å, T = 153 K), DyAsTe
(a = 7.4951(13) Å, b = 4.0246(7) Å, c = 9.8288(17) Å, T = 153 K), and ErAsTe (a = 7.4478(1) Å, b =
4.0078(1) Å, c = 9.7552(2) Å, T = 153 K) crystallize with four formula units in the orthorhombic space group
D2h16-Pnma. These compounds are isostructural and belong to the β-ZrSb2 structure type. In each compound, the
Ln atoms are coordinated by a tricapped trigonal prism of four As atoms and five Te atoms. The entire three-dimensional structure is built up by the motif of the LnAs4Te5 tricapped trigonal prisms. Infinite nonalternating
zigzag As chains are found along the b axis, with As−As distances in these compounds ranging from 2.5915(5)
to 2.6350(9) Å. Conductivity measurements in the direction of these As chains indicate that PrAsTe is metallic
whereas SmAsTe and DyAsTe are weakly metallic. Antiferromagnetic transitions occur in SmAsTe and DyAsTe
at 3 and 9 K, respectively. DyAsTe above 9 K follows the Curie−Weiss law.