[ [Math Processing Error] ] particles with non-aggregation characteristics were prepared by various conditions such as preparation temperature, flow rate of carrier gas, and concentration of spray solution using spray pyrolysis. The morphology and crystallinity of the preformed particles obtained by spray pyrolysis at various conditions affected the mean size and morphology of the post-treated [Math Processing Error] particles. The preformed particles with hollow and porous morphology obtained from spray solution with citric acid and ethylene glycol turned to [Math Processing Error] particles with nano size, regular morphology and non-aggregation characteristics after post-treatment at [Math Processing Error] . On the other hand, the preformed particles obtained by the preparation conditions of short residence time of particles inside hot wall reactor and high reactor temperature turned to [Math Processing Error] particles with aggregated morphology after post-treatment. The mean crystallite size and particle size of the [Math Processing Error] particles prepared from optimum preparation conditions were 47 nm and 210 nm at post-treatment temperature of [Math Processing Error] .