A Promising Proton Conducting Electrolyte BaZr1-xHoxO3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells
Deepash Shekhar Saini, Avijit Ghosh, S. Tripathy, Aparabal Kumar, Sanjeev Sharma, Nawnit Kumar, Shubhankar Majumdar, D. Bhattacharya
Abstract
Abstract In this study, the Ho-substituted BaZrO 3 electrolyte ceramics (BaZr 1- x Ho x O 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 BaZrO 3 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 $$Pm\bar{3}m$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>P</mml:mi><mml:mi>m</mml:mi><mml:mover><mml:mn>3</mml:mn><mml:mo>¯</mml:mo></mml:mover><mml:mi>m</mml:mi></mml:math> 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 BaZrO 3 ceramics. Field Emission Scanning Microscopic (FESEM) study informed a mixture of fine and coarse grains in the fracture surface of Ho-substituted BaZrO 3 sintered samples. The relative density and average grain size of samples were observed to decrease as per the addition of Ho-substitution in BaZrO 3 ceramics. The electrical conductivity study was accomplished by Electrical Impedance Spectroscopy (EIS) under 3% humidified O 2 atmosphere from 300 to 800 ° C . Furthermore, the total electrical conductivity of BaZr 0.8 Ho 0.2 O 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.