The problem of cation distribution in the layered tetradymite structure compound SnSb2Te4 is not completely resolved by means of classical X-ray or electron diffraction studies. Mossbauer absorption measurements, reported here, give experimental evidence for a symmetrical and distorted structural environment around the Sn and Sb atoms, respectively. Moreover, an ab initio free-parameter total-energy calculation reproduces in the Hellmann-Faynman scheme the forces acting on the ions which are equal to zero in the ordered phase. The results of the combined experimental and theoretical study indicate that the metal atoms are not arranged in a random sequence.
We report the discovery of a new superconductor from phase change materials SnSb2Te4. Single crystals of SnSb2Te4 were grown using a conventional melting-growth method. The sample resistance under pressure was measured using an originally designed diamond anvil cell with boron-doped diamond electrodes. The pressure dependence of the resistance has been measured up to 32.6 GPa. The superconducting transition of SnSb2Te4 appeared at 2.1 K(Tconset) under 8.1 GPa, which was further increased with applied pressure to a maximum onset transition temperature 7.4K under 32.6 GPa.
We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero.