Nature of structural changes in LSM-YSZ nanocomposite material during thermal treatments

Nanocomposite powders in the system (La1−xSrx)aMnO3-YSZ(1−y) [LSM-YSZ], as an attractive cathode material for high operating solid oxide fuel cell (SOFC), were obtained through ultrasonic spray pyrolysis (1.7 MHz) method. The principle of the synthesis is based on a single-step high temperature aerosol decomposition of atomized precursor solutions composed from yttria stabilized ZrO2 sol (average particle size ~ 60 nm) and corresponding aqueous nitrate and hydrogen peroxide solutions of La, Sr and Mn. Two starting systems were examined: (a) (La0.76Sr0.24)0.93MnO3 with 0% YSZ, and (b) (La0.77Sr0.23)0.92MnO3-YSZ0.81 with corresponding molar ratio LSM/YSZ=48:52. X-ray diffraction analysis of as-prepared powders showed the presence of a lanthanum magnesium oxide and yttrium zirconium oxide. Compositional homogeneity and particle morphology were determined by SEM analysis. LSM-YSZ obtained particles are spherical in shape, submicron in size and composed of primary subgrains. TEM analysis of ultra-cross section revealed dense-packed nanosized grains, several tens of nanometers in diameter. After powders calcination TEM observations confirmed dense particle structure composed of primary grains, with a mean diameter of around 100 nm. The structural changes expressed through the crystallite growth were analyzed by nonisothermal differential scanning calorimetry (DSC).