Anataselike Grain Boundary Structure in Rutile Titanium Dioxide

The
formation of nanoscale phases at grain boundaries in polycrystalline
materials has attracted much attention, since it offers a route toward
targeted and controlled design of interface properties. However, understanding
structure–property relationships at these complex interfacial
defects is hampered by the great challenge of accurately determining
their atomic structure. Here, we combine advanced electron microscopy
together with ab initio random structure searching
to determine the atomic structure of an experimentally fabricated
Σ13 (221) [11̅0] grain boundary in rutile TiO2. Through careful analysis of the atomic structure and complementary
electron energy-loss spectroscopy analysis we identify the existence
of a unique nanoscale phase at the grain boundary with striking similarities
to the bulk anatase crystal structure. Our results show a path to
embed nanoscale anatase into rutile TiO2 and showcase how
the atomic structure of even complex internal interfaces can be accurately
determined using a combined theoretical and experimental approach.