Chemistry of the alkoxy-derived precursor solutions for layer-structured perovskite thin films

Precursors for layer-structured perovskite thin films of SrBi2Ta2O9, or SBT, and SrBi2Nb2O9, or SBN were prepared by the reactions of a Sr-Bi double methoxyethoxide and Ta and/or Nb methoxyethoxide in methoxyethanol, followed by partial hydrolysis. Several analytical techniques such as 1H-, 13C- and 93Nb-NMR and FT-IR were used to determine the arrangement of the metals and oxygen in the precursor molecules. The precursors contain Sr-O-M (M; Ta or Nb) bonds (i.e., a Sr connects two MO6 octahedra), and Sr-O-Bi bonds with Bi atom bonded to the MO6 octahedron. This structure is similar to the layer-structured perovskite crystal sub-lattice. This is the origin of the low temperature crystallization.