Preparation of BiFeO_3 Nanopowders Using Acetylacetone as Stabilizer

摘要

The present investigation reports on the preparation of BiFeO_3 nanopowders by a sol-gel method using acetylacetone as a stabilizer. Single-phase BiFeO_3 nanopowders without any impurity or amorphous phases were obtained when the precursor was thermal treated at temperatures as low as 400℃ for 2 h. Acetylacetone (acac) plays an important role on lowering the formation temperature of pure phase BiFeO_3 nanopowders. It is found that Bi/acac molar ratio of 1/30 was favorable for a stable sol and for the lowest crystallization temperature of pure BiFeO_3 nanopowders. X-ray diffraction and Fourier transform infrared spectroscopy revealed that thermally induced crystallization process of BiFeO_3 nanopowders from Bi-Fe polymeric precursor. When the thermal treated temperature was below 200℃, only amorphous phase existed. With the temperature increasing up to 300℃, crystallized phase, carbonate, were detected. After annealed at 400℃, Bi-Fe precursor totally changed to rhombohedral BiFeO_3 nanopowders. Scanning electron microscopy characterized morphologies of BiFeO_3 nanopowders calcined at 400℃ and 500℃. The ferroelectric transition of BiFeO_3 nanopowders at 827℃ has been detected by differential thermal analysis.