Three-dimensional (3D) self-assembled hierarchical bismuth oxide architectures were prepared via a solution precipitation synthesis at 85 degrees C in 45 min with the aid of polyethylene glycol-8000 (PEG-8000) as a capping agent. The morphology and crystalline phase evolution was studied versus reaction time and capping agent concentration and interpreted in terms of growth mechanisms. At higher capping agent concentrations, the as-grown 3D hierarchical flowerlike bismuth oxide was crystalline cubic gamma-phase that was previously formed only at temperature > or =640 degrees C. The morphology and crystal structure of these 3D cubic gamma-phase bismuth oxide flowers were not changed with calcining up to 600 degrees C. Photoluminescence was attributed to emission from the Bi(3+) ion by a (3)P(0),(1) --> (1)S(0) transition and from defects. The gamma-phase flowerlike bismuth oxide shows better ion conductivity than that of rodlike bismuth oxide formed without the capping agent. The flowerlike morphology was attributed to modification of the nucleation and growth kinetics by the capping agent.