Synthesis and Structures of New Layered Ternary Manganese Tellurides: AMnTe2 (A = K, Rb, Cs), Na3Mn4Te6, and NaMn1.56Te2

The synthesis and crystal structures of new ternary manganese tellurides, AMnTe 2 (A = K, Rb, Cs), Na 3 Mn 4 Te 6, and NaMn 1.56 Te 2, are reported. These compounds are synthesized by solid-state reaction and cation exchange techniques in sealed Nb tubes. The single-crystal structures of AMnTe 2 (A = K, Rb), Na 3 Mn 4 Te 6, and NaMn 1.56 Te 2 have been determined; KMnTe 2: a = 4.5110(4) Å, c = 14.909(2) Å, I 4̄ m 2 (No. 119, Z = 2); RbMnTe 2: a = 4.539(1) Å, c = 15.055(2) Å, I 4̄ m 2 (No. 119, Z = 2); Na 3 Mn 4 Te 6: a = 8.274(4) Å, b = 14.083(6) Å, c = 7.608(6) Å, β = 91.97(4)°, C 2/ m (No. 12, Z = 2); NaMn 1.56 Te 2: a = 4.4973(8) Å, c = 7.638(2) Å, P 3̄ m 1 (No. 164, Z = 1). The fundamental building blocks of the title compounds are MnTe 4 tetrahedra. AMnTe 2 (A = K, Rb, Cs) are isostructural with TlFeS 2, consisting of layers built up by four corner-shared MnTe 4 tetrahedra. Manganese telluride layers in Na 3 Mn 4 Te 6 consist of two hexagonal nets of Te atoms between which two-thirds of the tetrahedral interstices are filled with Mn atoms to form two 6 3 honeycomb nets. NaMn 1.56 Te 2 adopts a defective CaAl 2 Si 2 structure type, in which Mn atoms partially and randomly occupy 78% of tetrahedral sites. Temperature-dependent magnetic susceptibilities measurements show that AMnTe 2 (A = K, Rb, Cs) exhibit Curie−Weiss paramagnetism, whereas Na 3 Mn 4 Te 6 and NaMn 1.56 Te 2 show paramagnetism with a weak dependence on temperature.