The characterization of mixed titanate Ba1−xSrxTiO3 phase formation from oxalate coprecipitated precursor


Mixed titanates Ba1−xSrxTiO3 were synthesized via calcination of oxalate coprecipitated precursors. On heating there were three thermal event occurred: T<250°C corresponds to the evaporation of trapped water and dehydration, T=250°C–450°C corresponds to the decomposition of oxalate and the formation of an intermediate phase where the composition is close to [Ba1−xSrx]2Ti2O5.CO3 and T=600°C–700°C corresponds to the carbonate decomposition and the formation of Ba1−xSrxTiO3 phase. Powders calcined at T=700°C for 2 h are single phase, have grain size ranges of 0.2–2 μm and elongated morphology. Rietveld refinements of the XRD data showed single phase of perovskite structure in which their tetragonality decreased with increasing concentration of Sr2+ incorporated in Ba2+ site. The transition temperature showed strong correlation with the tetragonality.


Powders-chemical preparation
X-ray methods
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