A Multiscale Perspective on Misfit Dislocations in Oxide Films

Felip Sandiumenge

doi:10.3389/fmats.2019.00013

Abstract

Misfit dislocations were conceived by Jan H. van der Merwe in 1949 (Frank, F. C., and van der Merwe, J. H. (1949). One-dimensional dislocations. I and II. Proc. Royal Soc. London. Series A. 198, 205-216 and 216-225), long before they were directly observed by transmission electron microscopy in the early sixties (Matthews, J. W. (1961). The observation of dislocations to accommodate the misfit between crystals with different lattice parameters. Phil. Mag. 6, 1347-1349; Delavignette, P., Tournier, J., and Amelinckx, S. (1961). Direct observation of dislocations due to epitaxy. Phil. Mag. 6, 1419-1420). Since then, their appreciation by the scientific community has evolved from being considered a drawback to being recognized as a challenging opportunity. However, taking full advantage of all their potential, sets out issues that despite being well established in semiconductor or metals, remain poorly understood in transition metal oxides. In this Perspective contribution, we select recent findings on misfit dislocations in La0.7Sr0.3MnO3 under compressive strain, to illustrate effects spanning a range of length scales, like the coupling between strain and defect chemistry in and around their cores, the impact of kinetics on the morphology of dislocated films, or the subtle sensitivity of oxide properties to dislocation strain fields.

Highlights

Dislocations are linear crystal defects that store their elastic energy at comparatively large distances from their sub-nanometer core, and can modify the properties of the host material at different length scales
The degree of order of the misfit dislocations (MDs) network and the amplitude of the fluctuation in chemical potential follow opposite dependencies on the film thickness: The former is enhanced with increasing thickness (MD density), whereas the later rapidly vanishes as the film surface moves apart from the strain source and the strain field of individual MDs overlap
The oxide thin film community has devoted, so far, a lot of interest to the investigation of fascinating and conceptually new film-substrate interfacial structures driven by octahedral tilting mechanisms in perovskite systems (Huijben et al, 2017)

Summary

A Multiscale Perspective on Misfit Dislocations in Oxide Films

Group of Advanced Characterization and Nanostructured Materials, Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Catalonia, Spain. Since misfit dislocations were first conceived by Jan H. van der Merwe in 1949 (Frank and van der Merwe, 1949), their appreciation by the scientific community has evolved from being considered a drawback to being recognized as a challenging opportunity. Taking full advantage of all their potential sets out issues that, despite being well-established in semiconductor or metals, remain poorly understood in transition metal oxides. In this Perspective contribution we select recent findings on misfit dislocations in.

INTRODUCTION

CONCLUDING REMARKS AND FUTURE