CATION DEFICIENCY IN (Ba, Sr)Co1-xOy HEXAGONAL PEROVSKITE RELATED OXIDES: NEW MEMBERS OF THE An+2B'BnO3n+3 HOMOLOGOUS SERIES

摘要

The new phases (Ba0.5Sr0.5)7Co6O18, Ba8Co7O21, and Ba9Co8O12 have been shown by electron diffraction and HREM to be three new members (n=5, n=6, and n=7) of the 2H hexagonal perovskite-related An+2B'BnO3n+3 homologous series. Their modulated structures are made up of chains, running along the c direction and separated by Ba(Sr) ions, containing a succession of one Co atom in prismatic trigonal sites and n Co atoms in octahedral coordination sharing faces. The strategy to synthesize different terms of this family is discussed in terms of the distance between AO3 layers. 18 refs.