Structure and conductivity of some fluoride ion conductors

The structure and conductivity of a number of doped β-PbF2 and BiF3 compounds have been investigated using neutron diffraction and impedance spectroscopy. Anion-deficient compounds in the system PbF2–MF with M=K, Rb display a high-temperature superionic phase with a body-centred cubic sublattice while an ordered cubic perovskite structure is observed for the composition PbCsF3. In the system PbF2–SnF2, the high-temperature structure of γ-PbSnF4 with cubic symmetry has been characterised. The solid solutions in the system PbF2–BiF3, where vacancy clustering is observed, and in the systems BiF3–KF and BiF3–RbF have also been investigated at high temperature.