Sol-gel preparation of Bi2MxV1-xO5.5-δ films (M = Cu, Nb; x = 0.1, 0.3)

The sol-gel deposition of Bi2Cu0.1V0.9O5.35 (BiCUVOx) and Bi2Nb0.3V0.7O5.5 (BiNbVOx) films up to 2 mu m thick onto quartz substrates is reported. Films of both materials can be deposited, initially crack-free, on quartz. Bi2Nb0.3V0.7O5.5 films on quartz remain homogeneous and defect-free at all temperatures, but Bi2CU0.1V0.9O5.35 films develop grooves and voids between grains during thermal processing. A number of additives were tested with the BiCuVOx precursor solutions for their effects on film morphology and were found to give no improvement in the film quality. Process temperature and alkoxide/hydrolysis water ratio were varied as well. Preliminary results for deposition of the films onto porous alumina substrates are reported.