  In the context of the search for environment-respectful, lead- and bismuth-
free chemical compounds for devices such as actuators, SnTiO3 (ST) is
investigated from first principles within DFT. Full geometry optimization
provides a stable tetragonal structure relative to cubic one. From the equation
of state the equilibrium volume of SnTiO3 is found smaller than ferroelectric
PbTiO3 (PT) in agreement with a smaller Sn2+ radius. While ionic displacements
exhibit similar trends between ST and PT a larger tetragonality (c/a ratio) for
ST results in a larger polarization, PST = 1.1 C.m2. The analysis of the
electronic band structure detailing the Sn-O and Ti-O interactions points to a
differentiated chemical bonding and a reinforcement of the covalent bonding
with respect to Pb homologue.
