Structure families of ZrO2- and CaTiO3-related ionic conductors

The oxygen atoms of cubic ZrO2 form a primitive cubic (pc) lattice. Two pos itions of the pc lattice are occupied by metal atoms in the perovskite-rela ted structures (PER group) of superconducting oxides. Many ZrO2-related str uctures with ordered oxygen defects square like Zr(3)Sc(4)square(2)O(12) or Cu2O square(3) and most superconducting oxides can be characterized by the ordering of the defects and oxygen atoms. The structures are analyzed by t he self-coordination numbers T-i of the oxygen atoms with other oxygen atom s in the i=1-3 coordination shell and the T-1, T-2 values plotted in struct ure maps. The T-i values can be correlated with attractive or repulsive int eractions and the mobility of oxygen atoms. The different structures can be classified in about 20 structure families like the Ruddlesden-Popper phase s. The characterization by sequences of structural units or sequences of co ordination numbers allows the search for new compounds with high oxygen mob ility. (C) 2000 Elsevier Science B.V. All rights reserved.