Controllable synthesis of metastable γ-Bi2O3 architectures and optical properties

Metastable gamma-Bi2O3 were successfully prepared via a controllable, facile and mild solution precipitation synthesis method in ethylene glycol-water mixed solvent systems without adding surfactant or template agents, at 80 degrees C and ambient atmospheric pressure in 40 min. Ethylene glycol can facilitate the nucleation of gamma-Bi2O3 as only alpha-Bi2O3 was observed in its absence. And by adjusting ethylene glycol (EG) volume fraction, metastable gamma-Bi2O3 submicro hexahedrons, tetrahedrons, polyhedrons and three-dimensional self-assembled hierarchical flower-like architectures were obtained respectively. SEM, XRD, and EDS were used to characterize the microstructures. The flower-like metastable gamma-Bi2O3 architectures with diameter of several micrometers were 3D self-assembled from tetrahedrons step by step. The formation of the hierarchical flower-like architectures was due to the controlling of crystal growth kinetics and the guidance of self-assembly approach by ethylene glycol. The possible formation mechanism of these metastable gamma-Bi2O3 architectures was also discussed. And compared with alpha-Bi2O3, beta-Bi2O3, delta-Bi2O3, and gamma-Bi2O3 through other means reported previously, the as-prepared gamma-Bi2O3 in this paper possesses more excellent optical performance.