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

Abstract

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.

Key Words:

• SrBi₂Ta₂O₉-SrBi₂Nb₂O₉
• sol-gel processing
• molecular structure of precursors
• sub-lattice of layer-structured perovskite