A Promising Proton Conducting Electrolyte BaZr_1-xHo_xO_3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature...

In this study, the Ho-substituted BaZrO₃ electrolyte ceramics (BaZr_1-xHo_xO_3-δ, 0.05 ≤ x ≤ 0.20) were synthesized through a low-cost flash pyrolysis process followed by conventional sintering. The effects of Ho-substitution in BaZrO₃ studied in terms of the structural phase relationship, microstructure and electrical conductivity to substantiate augmented total electrical conductivity for intermediate temperature solid oxide fuel cells (IT-SOFCs). The Rietveld refined X-ray diffraction (XRD) patterns revealed that pure phase with [Formula: see text] space group symmetry of cubic crystal system as originated in all samples sintered at 1600 °C for 8 h. The Raman spectroscopic investigations also approved that Ho incorporation in BaZrO₃ ceramics. Field Emission Scanning Microscopic (FESEM) study informed a mixture of fine and coarse grains in the fracture surface of Ho-substituted BaZrO₃ sintered samples. The relative density and average grain size of samples were observed to decrease as per the addition of Ho-substitution in BaZrO₃ ceramics. The electrical conductivity study was accomplished by Electrical Impedance Spectroscopy (EIS) under 3% humidified O₂ atmosphere from 300 to 800 °C. Furthermore, the total electrical conductivity of BaZr_0.8Ho_0.2O_3-δ ceramic was found to be 5.8 × 10^-3 S-cm^-1 at 600 °C under 3% humidified atmosphere, which may be a promising electrolyte for IT-SOFCs.