Above: Combining advanced atomic-resolution scanning transmission electron microscopy imaging and computational structure prediction in the form of ab initio random structure searching (AIRSS), allows for determination of the unique grain boundary phase at the Σ13(221)[11 ̅0] grain boundary.
A collaboration between researchers at Cambridge and AIMR has shed light on grain boundary structures in titania.
In this international collaboration a unique nanoscale structure, with striking similarity to bulk anatase titanium dioxide (TiO2), is found in rutile TiO2 in the form of a localized grain boundary phase. TiO2 is of great technological importance, finding application in photocatalysis, catalysis, photovoltaics, gas sensors, and other novel technologies. The ability to control the local crystal phase at the nanoscale is crucial, since different structures exhibit often vastly different properties.
Traditionally, theoretical models for grain boundary interfaces are built by hand, based on (2D) images from electron microscopy. This often assumes that the same bulk crystalline phase persists at the interface with only minor deviations due to matching conditions at the boundary. Computational modeling often only enters as a mere ‘after-thought’, used to optimize the atomic structure such that the nearest local minimum is found, crucially not exploring a large phase space. To identify the very unique structure found at the interface we fabricated here, we follow an innovative approach combining advanced atomic-resolution scanning transmission electron microscopy (STEM) imaging and computational structure prediction in the form of ab initio random structure searching (AIRSS). This allows us to explore a much larger space of possible phases and really enabled the determination of the atomic structure of the nanoscale phase forming at the interface.
The research has been published in Nano Letters.
Anataselike Grain Boundary Structure in Rutile Titanium Dioxide
Georg Schusteritsch, Ryo Ishikawa, Abdul Razak Elmaslmane, Kazutoshi Inoue, Keith P. McKenna, Yuichi Ikuhara, and Chris J. Pickard