Strontium tetrastannide, SrSn4, is a superconducting
stannide with localized and delocalized bond character.This compound is the tin-richest phase in the system Sr–Sn and is obtained by stoichiometric combination of the
elements. SrSn4 decomposes in a peritectic manner with
formation of SrSn3 and Sn at 340°C. The structure determined
from a single crystal shows a new structure type
with a novel structure motive in tin chemistry. It can be
described by a corrugated, distorted quadratic net of tin
atoms as the only building unit. The nets intersect at
common Sn atoms, and the resulting channels host the
Sr atoms.
The structure can alternatively be described as an
intergrowth structure of the AlB2-type and W-type.
The atoms that are connected by the two shortest
Sn–Sn distances (2.900 and 3.044 ? ) form a two-dimensional
net consisting of hexagons of tin atoms. The hexagons
have boat conformation in contrast to the rather
similar alpha-As structure type, where hexagons have
a chair conformation. Further tin atoms connect the
two-dimensional net of Sn hexagons. Temperaturedependent
magnetic susceptibility measurements
show that SrSn4 is superconducting with T(c) = 4.8 K
at 10 G. LMTO band structure and density of states
(DOS) calculations verify the metallic behavior of
SrSn4.
