Microstructure and cathodic performance of La0.9Sr0.1MnO3 electrodes according to particle size of starting powder

Three La0.9Sr0.1MnO3 (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 an d 11.31 mu m, respectively. The microstructural changes evolved during the course of electrode adhesion and half-cell operation are traced by taking s canning electron micrographs, and the cathodic activity is measured at 900 degrees C in air using AC impedance spectroscopy. The LSM1 electrode prepar ed from the smallest powder shows good initial activity, but a rapid decrea se in activity along with notable particle growth is observed within a shor t period of time. By contrast, the LSM3 electrode fabricated with the large st powder has a poor initial activity but the loss in activity is not appre ciable as particle growth is insignificant. The LSM2 electrode that is prep ared from medium-sized powder gives the best performances in terms of initi al activity and long-term stability. It is likely that the LSM2 electrode h as a larger number of active sites for the oxygen reduction reaction than L SM3 and the loss of active sites due to particle growth is less severe than with the LSM1 electrode. (C) 2000 Elsevier Science S.A. All rights reserve d.