Synthesis of BaSm₂Ti₄O₁₂ via polymeric precursor method

A polymeric precursor method by using citric acid as the chelating agent was investigated and single-phase and well-crystallized BaSm₂Ti₄O₁₂ powder was synthesized at 1000°C for 3 h. As a comparison, an oxalate co-precipitation method was applied to synthesize BaSm₂Ti₄O₁₂ powder, but 1300°C was needed to get the pure BaSm₂Ti₄O₁₂. The different phase behavior and reaction sequences are here believed to answer for the different calcining temperatures needed via these two wet chemical methods. In the co-precipitation method, when heating the precipitate, intermediate phase Sm₂Ti₂O₇ reacts with BaTi₄O₉ and BaTiO₃ to produce BaSm₂Ti₄O₁₂, which is similar to the solid-state route. As to the polymeric precursor route, however, BaTi₂O₅ intermediate phase produces during the thermal decomposition process, which results in totally different reaction sequences from the solid-state reaction mechanism, and promotes the formation of BaSm₂Ti₄O₁₂ phase.