Active Lone Electron Pair of Cations and Ionic Conductivity

4 Active Lone Electron Pair of Cations and Ionic Conductivity 

A lone electron pair deforming and sometimes changing the crystal structure and conductivity channels influences the conductive properties of materials. There is a good example of the lone electron pair s influence, namely the oxyfluoride solid solutions based on NdOF and BiOF having a fluorite-like structure. Both phases have an identical anionic composition, similar structures and close cation radii 

Phase [References] Crystal System Relation to the fluorite lattice ao (TAOOK. ki Tcm 

PbSnF4 is the most conductive phase among fluorides and both cations Pb and Sn have lone electron pairs. The PbSnp4 structure is strongly distorted in comparison with B-PbF2 fluorite and Pbi xSnxF2 solid solutions [27] due to the ordered location of Pb and Sn cations. The layered stmcture PbPbSnSnPbPbSnSn causes the conductivity anisotropy to be smoothed in different-oriented pressed powder samples. 

The lattice parameters of a-PbSnF4 are related to those of the parent fluorite structure by a a = Cq, = 2afi- The stabilization of the layered structure is generally attributed to 

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