Materials synthesis and characterization of 8YSZ nanomaterials for the fabrication of electrolyte membranes in solid oxide fuel cells

Two different nanosized materials were synthesized by two preparation methods, namely a sonochemical technique and a spray pyrolysis process. The powder properties, the sintering behavior and the resulting crystallinity with respect to their utilisation for solid oxide fuel cell electrolytes were investigated. While the spray pyrolysis provides crystallized powder without any organic residue, the sonochemical powder is amorphous with some organic residue. Crystallization begins in the 400–500 °C temperature domain. The particle sizes vary between 10 and 50 nm for the sonochemical powder and between 50 nm and 1 μm for the spray pyrolysis powder, as determined by SEM analyses. Crystal growth of both powders starts between 800 and 1000 °C. After heating and sintering at 1300 °C the resulting grain sizes of the spray pyrolysis powder are 5 times larger than those of the sonochemical powder (about 250 nm and 1.2 μm, respectively). Additionally, the maximum rate of grain growth for the spray-pyrolysed material at 97 nm/h is even higher compared with 22 nm/h for the sonochemical powder.