New refinement of Ni5.20Sn8.7Zn4.16Cu1.04and its non-isotypy with Ni2Sn2Zn

Abstract

The noncentrosymmetric space groupP\overline{4}3mbut a pseudocentric cubic crystal structure were reported for the compound Ni5.20Sn8.7Zn4.16Cu1.04[Larssonet al.(1994).Acta Cryst.C50, 9–12]. The recently described Ni2Sn2Zn shows a closely related structure, although it is centrosymmetric and contains additional voids which are partially occupied. Therefore, a new refinement of Ni5.20Sn8.7Zn4.16Cu1.04based on the originally published structure factors was performed. The results indicate that the structure can indeed be described in the centrosymmetric space groupPm\overline{3}m; no justification for the absence of the inversion centre could be found within the accuracy of the available data. In comparison with Ni2Sn2Zn, slight but significant differences were confirmed; consequently, the two structures are topologically related but not isotypic.