Chemical Processing and Characterization of Ta2O5-TiO2
D. A. Payne,* S. Hemjinda
Nippon Steel Foundation

Thin films of TiO2-modified Ta2O5 were deposited on silicon substrates by sol-gel processing. Stable hydrolyzed solutions were prepared. With addition of dilute HCL, precipitation was avoided in solutions with Rw rations greater than 1. Additions of Ti(ISP)4 not only improved the solution stability and promoted gelation, but also the onset of the crystallization temperature. The refractive index of Ta2O5-TiO2 films was determined to be dependent on Ti-content. Dense crack-free films with thicknesses ranging from 500-1000 Å were successfully integrated on silicon. XRD data indicate the formation of a low-temperature orthorhombic Ta2O5 phase.

Aqueous Synthesis of Nb and Ti Containing Oxides
D. A. Payne,* D. L. West, in collaboration with W. G. Klemperer and K. A. Marek in the Department of Chemistry
U.S. Department of Energy, DE-FG02-96ER45439 (In cooperation with the Materials Research Laboratory)

Solution synthesis of Nb and/or Ti containing oxides is often effected with alkoxide or chloride precursors. Unfortunately, the alkoxides and chlorides of these metals are moisture sensitive and require special processing. We intend to develop solution synthesis for Nb and Ti containing oxides that employ air stable, aqueous precursors.We begin by transposing Nb2O5 or TiO2 with alkali compounds. Wet chemistry techniques are then employed to separate the alkalis and produce aqueous Nb or Ti precursors. Currently, we are optimizing these precursors for use in synthesis techniques such as co-precipitation and the Pechini process.