Dissolution of A15 in lamellar metallic dichalcogenides: Mössbauer study of the superconductor SnNb5Se9

摘要: Abstract The new selenide SnNb5Se9 has been synthesized and characterized. Magnetic properties show a superconducting behaviour at 17.5 K an anomaly around 85–90 K, probably indicating condensation of conduction electrons in CDW state. From the results 119Sn Mossbauer studies, 3 types sites exist which correspond to 2 species Sn. One site is for Sn Nb environment (site 1), two others Sn(II) Se environment. Both thermic treatment end synthesis during experiments are deciding factors distribution (symmetrical) (asymmetrical). At 90 K, quenched phases, conversion symmetrical into asymmetrical occurs. It reversible dynamic process between 3, corresponds modification 1 whose symmetry itself changes 90 K. Thus given suceptibility temperature parameters surrounded by reveals possible distortion.