Crystal Structures and Properties of the Thiostannates Eu2SnS4 and Sr2SnS4 and the Selenogermanate γ‐Sr2GeSe4

Abstract

AbstractEu2SnS4, Sr2SnS4, and Sr2GeSe4 have been synthesized by heating the elements or binary precursors at 1073 K and their crystal structures were determined by single crystal methods. Eu2SnS4 crystallizes with a new structure type (Pnma, a = 11.187(2), b = 8.768(2), c = 7.538(2)Å, Z = 4), consisting of distorted [SnS4]4— tetrahedra and sevenfold coordinated Eu2+ ions. Sr2SnS4 and γ‐Sr2GeSe4 are isostructural and form a new structure type likewise (Ama2, Z = 4, Sr2SnS4: a = 9.977(1), b = 10.311(2), c = 7.243(1)Å, Sr2GeSe4: a = 10.284(2), b = 10.543(2), c = 7.411(1)Å) with more regular tetrahedral anions and strontium coordinated by seven and eight chalcogen atoms, respectively. Eu2SnS4 is a Curie‐Weiss paramagnet (7.80(2) μB/Eu; θ = 4.2(2) K) and orders antiferromagnetically at TN = 5.5(2) K with a magnetization of 6.56(5) μB/Eu at 5.5 T. The divalent nature of europium is also evident from 151Eu Mössbauer spectra which show a single signal at an isomer shift of —12.2(1) mm/s at 78 K. Full magnetic hyperfine field splitting (19.5(2) T at the europium nuclei) is observed at 4.2 K. The 119Sn spectrum shows one signal at 1.25(9) mm/s subject to quadrupole splitting of 0.76(2) mm/s. At 4.2 K a transferred hyperfine field of 3(1) T is detected at the tin site.