Synthesis and electrical characterization of BaZr_0.9Ho_0.1O_3-δ electrolyte ceramic for IT – SOFCs

A cost-effective modified combustion method using citric acid and glycine has recently been developed to synthesize high quality, and nanosized BaZr_0.9Ho_0.1O₃ ceramic powder. BaZr_0.9Ho_0.1O_3-δ ceramic powder was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). XRD pattern of BaZr_0.9Ho_0.1O_3-δ ceramic sintered at 1600 °C has shown that pure phase of BaZr_0.9Ho_0.1O_3-δ with cubic Pm3̄m space group symmetry. The transmission electron microscopic investigation has shown that the particle size of the powder calcined at 1100 °C was in the range 30–80 nm. The FESEM image of sintered pellet at 1600 °C for 4 h reveals porous nature of BaZr_0.9Ho_0.1O_3-δ with 83.7 relative density. Impedance analysis reveal three type relaxations in the temperature range 250 °C to 500 °C as studied at different frequencies over 100 Hz to 1 MHz in air. The grain boundary conductivity of BaZr_0.9Ho_0.1O_3-δ ceramic is found lower then grain (bulk) conductivity due to core-space charge layer behavior in grain boundary.