Lone electron pair (E) role on the crystal structures and the mechanism of high ionic conductivity of PbSnF4E2. Stereochemical and ab initio investigations

Samir F. Matar (1) , Jean Galy (2)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 LCTS - Laboratoire des Composites Thermostructuraux

The F– anion mobility of archetype fast ionic conductor PbSnF4 formerly investigated by neutron diffraction with temperature is revisited based on a joint stereochemical and DFT investigation. It is mainly shown that a rapid exchange between F anions at the different tetragonal lattice sites is enhanced within the polyhedra enclosing the lone pair E in a dynamic change of coordination from octahedral to square pyramidal as for Sn(II). E stereoactivity in the interspaces along c direction is illustrated by the electron localization function ELF isosurface representations and followed by the non linear change of the c lattice constant with temperature.

Domaines: Matériaux

Samir F. Matar, Jean Galy. Lone electron pair (E) role on the crystal structures and the mechanism of high ionic conductivity of PbSnF4E2. Stereochemical and ab initio investigations. Solid State Sciences, 2016, 52, pp.29-36. ⟨10.1016/j.solidstatesciences.2015.11.011⟩. ⟨hal-01254592⟩