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Influence of surface orientation on the photochemical reactivity of CaTiO 3
Author(s) -
Zitello Kayla E.,
Salvador Paul A.,
Rohrer Gregory S.
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17107
Subject(s) - reactivity (psychology) , crystallite , materials science , scanning electron microscope , perovskite (structure) , aqueous solution , diffraction , chemistry , crystallography , optics , composite material , medicine , alternative medicine , physics , pathology
The orientations and surface structures of ferroelastic CaTiO 3 crystals within a polycrystalline ceramic were measured by electron backscatter diffraction and atomic force microscopy (AFM) respectively. Surfaces annealed at 1250°C in air are made up of a combination of facets with orientations near {100}, {110}, and {111} (indexed with reference to the cubic perovskite cell). The samples were immersed in an aqueous AgNO 3 solution and illuminated to photochemically reduce silver. Based on the amount of silver reduced on different surfaces, it was determined that surfaces with a {111} orientation had the greatest photocathodic reactivity, those with a {110} orientation had the least photocathodic reactivity, and surfaces with the {100} orientation had intermediate reactivity. While the {110} surfaces were essentially inert for photocathodic reduction, they were active for the photoanodic oxidation of Mn 2+ . Ferroelastic domains were observed to enhance and retard the photochemical reduction of silver on spatially alternating domains on 20% of the grains. However, domains had no influence on the reactivity of the other 80% and are therefore secondary to the surface orientation in determining the reactivity.