Photochemical Reactivity of Titania Films on BaTiO₃Substrates: Influence of Titania Phase and Orientation

Titania films were grown on BaTiO 3 (BTO) substrates by pulsed laser deposition to create (001) Anatase ||(100) BTO, (100) Rutile ||(111) BTO, and (110) Rutile ||(110) BTO heterostructures. The photochemical reactivity was evaluated by observing the amount of silver reduced by each film under identical conditions. The thickest films (100 nm) had reactivities that varied with the phase of titania and the crystal orientation. Thin films (15 nm), on the other hand, had reactivities that were approximately the same. Furthermore, reaction products were spatially distributed in patterns consistent with the underlying domain structure of the substrate. For the case of (110) Rutile ||(110) BTO, the thin films are more reactive than the thick films, showing that the dipolar fields in the ferroelectric substrate enhance the reactivity of (110) rutile.