Study on pyrolysing behavior of NiO-SDC composite particles prepared by spray pyrolysis technique

The NiO-samaria doped ceria (SDC) composite powders were prepared by spray pyrolysis technique at temperatures between 400 and 1000 °C. The variation of the particle structure was investigated by X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), scanning electron microscope (SEM), and transmission electron microscope (TEM)-energy-dispersive X-ray spectroscopy (EDS). The thermal analysis of raw materials was also carried out. The following facts became clear in this study. Ceria and nickel have been already separated at 400 °C. Samaria is amorphous phase below 600 °C, and is dissolved in ceria at 600 °C or higher. Samaria is distributed uniformly inside the particles before dissolving in ceria. The thermal decomposition temperatures of metal nitrate are: cerium < nickel < samarium. The results of these analyses were explained without contradiction. It was found that it is important to optimize the state of liquid drop before thermal decomposition in order to control the microstructure with this type of particle.