Nanoscale Quantification of Octahedral Tilts in Perovskite Films

TL;DR

This study uses advanced electron microscopy techniques to quantify how octahedral tilts in ultrathin LaNiO3 films change under biaxial tensile stress, revealing significant structural modifications at the nanoscale.

Contribution

It introduces a method to precisely measure octahedral tilt variations in perovskite films using PACBED and simulations, providing new insights into strain-induced structural changes.

Findings

Out-of-plane tilt increases by ~20% under tensile stress

In-plane rotation decreases by ~80% under tensile stress

Method enables nanoscale quantification of octahedral tilts

Abstract

NiO6-octahedral tilts in ultrathin LaNiO3 films were studied using position averaged convergent beam electron diffraction (PACBED) in scanning transmission electron microscopy. Both the type and magnitude of the octahedral tilts were determined by comparing PACBED experiments to frozen phonon multislice simulations. It is shown that the out-of-plane octahedral tilt of an epitaxial film under biaxial tensile stress (0.78 % in-plane tensile strain) increases by ~ 20%, while the in-plane rotation decreases by ~ 80%, compared to the unstrained bulk material.