Low-temperature electrodeposition of the high-temperature cubic polymorph of bismuth(III) oxide

Nanocrystalline films of delta-Bi2O3 were electrodeposited at 65 degrees C directly from alkaline solutions of tartrate-complexed Bi(III). This face-c entered-cubic polymorph of Bi2O3 is normally only stable at high temperatur es (729-825 degrees C). The material has the highest known oxide ion mobili ty. We propose that the high temperature form of the oxide is stabilized du e to the nanocrystalline (70 nm) size of the particles in the film. The oxi de also deposits epitaxially onto a single-crystal Au(110) substrate with s trong in-plane and out-of-plane orientation. The large lattice mismatch (35 .4%) is accommodated by forming a coincidence lattice, in which the delta-B i2O3 is rotated 90 degrees relative to the Au (110) substrate. The epitaxia l relationship between film and substrate may also serve to stabilize the h igh-temperature structure. (C) 2000 Elsevier Science B.V. All rights reserv ed.