Structure and photocatalytic property of perovskite and perovskite-related compounds

Perovskite (ABO3) and perovskite-related (brownmillerite, A2B2O5) compounds were prepared by citrate–nitrate combustion method. Crystal structure was verified by X-ray diffraction. Absorbency was determined by UV–vis spectrophotometer. FTIR was also used to determine whether the decoloration of methyl orange solution was caused by photocatalysis. SEM was used to compare the morphology of the samples prior to and after photocatalysis. Calcination temperature of the samples was maintained at 450 °C for 2 h and 800 °C for 4 h. It was supposed that the presence of different photocatalytic properties among synthesized perovskite (ABO3) and perovskite-related (brownmillerite, A2B2O5) compounds was derived from structural differences among those materials; moreover, transition-metal ions (Fe3+ and Co2+) in oxygen coordinated octahedra were the main source of photocatalytic abilities and alkaline-earth metal ions (Ca2+, Sr2+ and Ba2+) play important roles in stabilizing perovskite structure. And photocatalysis has no influence on the morphology of the sample.