CHEN Jishi , ZHANG Junji , WU Xiujuan , YUAN Xiaoman , WU Bin

(School of Materials Science and Engineering, Dalian Jiaotong University, Dalian Liaoning 116058, China)

Abstract: Potassium niobate (KNbO₃) powder was successfully synthesized via the citric acid gel-combustion process by using KNO₃ and Nb₂O₅·H₂O as the raw materials. Nb₂O₅·H₂O was obtained at first. Thermal behavior of the precursor was determined by TG-DSC technique. The structure, morphology and size of samples were characterized by the X-ray diffraction and the transmission electron microscope. It was found that excess citric acid and carboxylate mixture decomposed at about 330℃ to form carbonate. KN phase was supposed to nucleate directly from the amorphous precursor at about 600℃ without the formation of any intermediate phase. The powders calcined at temperature higher than 600℃ were uniform, well dispersed and regular nanoparticles. The grain sizes and crystallinity ascend with the calcination temperature increasing.

Key words: potassium niobate; gel-combustion method; nanocrystalline