Morphology control and optical properties of Bi 2 O 3 crystals prepared by low‐temperature liquid phase method

γ‐Bi 2 O 3 powders were prepared from [Bi(NO 3 ) 3 ·5H 2 O] and NaOH through low‐temperature liquid phase method at <90°C. This process featured low cost, simplicity and a normal pressure. Bismuth oxides were synthesised in large quantities in water systems. Morphology, structure and optical properties were characterised by X‐ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible absorption spectrophotometry (UV–Vis). The SEM indicated that tetrahedral Bi 2 O 3 with the edge length of 1–5 μm was formed. The FTIR spectra show a chemical bond of Bi–O existed. Bi 2 O 3 presents the photo absorption properties from UV light region to visible light and the band gap of the Bi 2 O 3 is 3.0 eV.