Anataselike Grain Boundary Structure in Rutile Titanium Dioxide.

Georg Schusteritsch,Keith P Mckenna,Chris J Pickard,Ryo Ishikawa,Abdul Razak Elmaslmane,Yuichi Ikuhara,Kazutoshi Inoue

doi:10.1021/acs.nanolett.0c04564

Abstract

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.

Highlights

All naturally occurring and most artificially fabricated materials are polycrystalline, with interfaces forming between the different grains, so-called grain boundaries
Designing materials with grain boundaries of a specific phase remains a significant obstacle and new approaches need to be established to advance this field toward “interfaces by design”. We address this major challenge in ceramic science using a combined theory and experimental approach combining atomic-resolution scanning transmission electron microscopy (STEM) with state of the art computational interface structure prediction techniques
In this work we demonstrate how an approach combining state of the art computational methods and experimental imaging spectroscopy techniques can be used to address the challenge of determining the atomic structure of interfaces a great obstacle that has for long hampered understanding of the structure−property relationship of interfaces and is key in advancing materials by design beyond purely crystalline systems toward complicated systems of importance to many devices

Summary

■ INTRODUCTION

All naturally occurring and most artificially fabricated materials are polycrystalline, with interfaces forming between the different grains, so-called grain boundaries. Some work on the properties of specific TiO2 grain boundaries does exist already, indicating that the exact structure the grain boundary phases possess strongly affects the bulk behavior.[2,14−19] Sun et al for instance previously studied the Σ3 (112) [11̅0] grain boundary in TiO2 and showed grain boundary phase transformations induced by heat and atmospheric treatment.[2] Gao et al studied We address this major challenge in ceramic science using a combined theory and experimental approach combining atomic-resolution scanning transmission electron microscopy (STEM) with state of the art computational interface structure prediction techniques. To ascertain the atomic structure of the grain boundary, we initially consider HAADF STEM images along the ⟨11̅0⟩ and ⟨114̅⟩ directions, shown in Figure 1a and d, respectively

■ CONCLUSION

■ ACKNOWLEDGMENTS

■ REFERENCES