Effect of process parameters on combined EDTA-citrate synthesis of Ba0.5Sr0.5Co0.8Fe0.2O3 - δ perovskite

Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) has been synthesized following combined EDTA-citrate method as a function of different process parameters viz. variation of molar ratio of EDTA:citric acid:metal ions in the precursor solution and pH of the precursor solution. Thermal decomposition behavior study of the precursor gel reveals that EDTA strongly influences the citrate/nitrate complex formation. The BSCF phase formation is preceded by formation and dissolution of several intermediate phases. The pure phase BSCF powder is obtained on calcining the combustion residue at 950 degrees C and above. A possible schematic reaction sequences leading to the formation of pure phase BSCF powder have been suggested from the study of XRD pattern as a function of calcination temperatures. The synthesized powders are found to be agglomerated. The agglomeration size changes with change in the process parameters. The densification behavior of the BSCF samples has been correlated with the powder characteristics. (C) 2011 Elsevier B.V. All rights reserved.