Sol-gel synthesis and protonic conductivity of yttrium doped barium cerate

摘要

Proton ion conducting nanocrystalline yttrium doped barium cerate (BCYO) is synthesized by EDTA-citric acid assisted sol-gel method. The effect of pH of the precursor on crystal structure, morphology and ionic conductivity is studied in pH range 6-11. The X-ray diffraction studies indicate that pure orthorhombic perovskite phase is obtained in acidic precursor pH of 6 at much lower calcination temperature (900 A degrees C) than that reported earlier. Increase in pH causes formation of impurities, such as, BaCeO3, Ce(OH)(2) and Ce0.8Y0.2O3 along with orthorhombic and monoclinic phases of BCYO. This deteriorates the sintered density and ionic conductivity of the samples. The sample prepared at pH 6 and sintered at 1,350 A degrees C shows above 95 % of the theoretical density. Ionic conductivity of about 0.04 S cm(-1) at 700 A degrees C and activation energy of 0.16 +/- A 0.01 eV between 500-700 A degrees C is obtained at pH 6, which are the best values reported for BCYO.