The stannides ScNi_1.54(1)Sn and ScNi_1.85(1)Sn - structures, ⁴⁵Sc NMR and ¹¹⁹Sn Mössbauer spectroscopy

Abstract

The stannides ScNi_1.54(1)Sn and ScNi_1.85(1)Sn were prepared from the elements by arc-melting. Single crystals were investigated on the basis of X-ray diffractometer data: MnCu₂Al type (Heusler structure), Fm3‾m, a=618.5(1), wR2=0.0110, 44 F² values, 6 variables for ScNi_1.54Sn and a=621.4(2), wR2=0.0242, 46 F² values, 6 variables for ScNi_1.85Sn. The scandium and tin atoms build up a rocksalt type substructure in which the tetrahedral voids are partially occupied. This way the scandium and tin atoms both have cubic nickel coordination. Both samples have been studied by ¹¹⁹Sn Mössbauer and ⁴⁵Sc solid state NMR, revealing single tin and scandium sites, in agreement with the crystal structures. The spectroscopic data also account for the different defect formation.