Microstructure and electrical properties of plasma sprayed Gd0.15Ce0.85O2-δ coatings from solution combustion synthesized flowable powders

Powders of Gadolinia doped Ceria (Gd0.15Ce0.85O2-δ (GDC)), a promising electrolyte material for intermediate temperature solid oxide fuel cell has been prepared by solution combustion (SC) synthesis. Variation of fuel to oxidizer ratio in the synthesis results in the GDC powder with varied powder characteristics. Fuel deficient combustion reaction results in GDC powder with smaller crystallites size but with larger agglomerates; whereas reaction with near stochiometric amount of fuel leads to the GDC powder with larger crystallite size and smaller agglomerates. Powders with large agglomerates possess required particle size, shape and flowability characteristics appropriate for plasma spraying. Electrolyte coatings fabricated from the synthesized plasma spray grade powders exhibit superior inter splat adhesion and conductivity (∼0.02 S/cm at 600 °C). Dense nature of the coating is ascribed to the complete melting of the porous GDC particles in the plasma flame. Powders prepared with stochiometric fuel are suitable for tape casting process.