Polymeric precursor synthesis of Ba2Ti9O20

Ba₂Ti₉O₂₀ was synthesized by Pechini method using citric acid as a chelating agent and ethylene glycol as an esterification agent. The effects, of the pH of the starting solutions and the molar ratio of citric acid to total metal cations concentration on the formation of Ba₂Ti₉O₂₀, were investigated. Increasing the pH of the starting solutions enhances the formation of Ba₂Ti₉O₂₀, but the increase of the molar ratio of citric acid to total metal cations concentration retards the formation of Ba₂Ti₉O₂₀ due to increased diffusion distances. Single-phase Ba₂Ti₉O₂₀ was obtained at 1200 °C for 4 h when the molar ratio of citric acid to total metal cations concentration was unity, regardless of the pH of the starting solutions. Increasing the molar ratio of citric acid to total metal cations concentration up to 2, single-phase Ba₂Ti₉O₂ was synthesized at 1200 °C for 6 h for the precursors with pH 3.5 and 6, but not for the precursors with pH 2.0. DTA, TG, XRD, FT–IR spectroscopy and Raman spectroscopy were used to characterize the precursors and the derived oxide powders. Details of the synthesis and characterizations of the resultant products were given.