Microstructure and cathodic performance of La sub(0.9)Sr sub(0.1)MnO sub(3) electrodes according to particle size of starting powder

Three La sub(0.9)Sr sub(0.1)MnO sub(3) (LSM)/YSZ (yttria-stabilized zirconia) electrodes are prepared from LSM powders of different particle size via the silk-printing technique. The mean particle size of the three LSM powders is 1.54, 5.98 and 11.31 mu m, respectively. The microstructural changes evolved during the course of electrode adhesion and half-cell operation are traced by taking scanning electron micrographs, and the cathodic activity is measured at 900 degree C in air using AC impedance spectroscopy. The LSM1 electrode prepared from the smallest powder shows good initial activity, but a rapid decrease in activity along with notable particle growth is observed within a short period of time. By contrast, the LSM3 electrode fabricated with the largest powder has a poor initial activity but the loss in activity is not appreciable as particle growth is insignificant. The LSM2 electrode that is prepared from medium-sized powder gives the best performances in terms of initial activity and long-term stability. It is likely that the LSM2 electrode has a larger number of active sites for the oxygen reduction reaction than LSM3 and the loss of active sites due to particle growth is less severe than with the LSM1 electrode.