Low temperature powder synthesis of LaAlO3 through in situ polymerization route utilizing citric acid and ethylene glycol

Powders of LaAlO3 with large surface areas were synthesized by the polymerized complex technique based upon in situ polyesterification between citric acid (CA) and ethylene glycol (EG). Heating of a mixed solution of CA, EG, and nitrates of lanthanum and aluminium at 130 degrees C gave brown transparent gel without any precipitation. The gel was preheated at 350 degrees C to give a black powdery mass, which was subsequently used as a precursor for LaAlO3. The formation of pure perovskite LaAlO3 occurred when the precursor was heat-treated in a furnace set at 700 degrees C for 8 h or at 750 degrees C for 2 h. No X-ray diffraction evidence for the presence of crystalline impurities was obtained. The LaAlO3 powder prepared by the polymerized complex method had a considerably large surface area in the range of 13-16 m(2) g(-1) when compared with similar to 0.3 m(2) g(-1) for the conventional solid-state reaction powder of the same compound. (C) 1998 Elsevier Science S.A.