The crystallographic orientation and atomic termination layer of oxide catalysts are known to influence their reactivity. The objective of this work was to measure how the relative photochemical reactivities of two ternary titanates vary with surface orientation and composition. The surface structure property relationships derived from these observations can be used to define optimized photocatalyst microstructures.

To measure the relative reactivity of surfaces with different orientations, crystallites (∽ 20 μm in diameter) in a polycrystalline ceramic were examined individually. First, polycrystalline specimens of BaTiO3 and SrTiO3 were synthesized using conventional ceramic processing. Surfaces for analysis were prepared by polishing and thermal etching in air. The surface orientations of selected grains in the sample were then determined from backscattered electron diffraction patterns recorded in a scanning electron microscope. to make a local measurement of the photochemical activity of each grain, we used a well established probe reaction (the reduction of aqueous Ag+ to Ag0) that deposits metallic silver on the surface as a reaction product.