New BaC0O3-δ polytypes by rational substitution of O2- for F-

The use of rational substitution of O2- for F- for synthesis of BaCoO3-δ polytypes, was investigated. The 5H form and 12 H form of BaCoO3-δ, Ba5Co5FO 13-δ, and Ba6Co6FO16-δ were analyzed using ab initio calculations, density functional theory, and VASP code. The Kohn-Sham equations were solved using the generalized gradient approximation (GGA) functionals for correlation. The c parameter of the 6H structure was doubled in order to use same cell volume for all compounds. It was observed that displacement of the apical Ba toward the central O2- led to short Ba-O distance in Ba6Co6O17. Result shows that the rational substitution of O for F in cubic deficient [BaO 2] layers act as method for synthesis of new material.