Asymmetric Lattice Disorder Induced at Oxide Interfaces

TL;DR

This study investigates how interfaces influence lattice disorder in oxide heterostructures, revealing asymmetric oxygen vacancy formation driven by structural differences, which could guide defect control in energy materials.

Contribution

It provides new insights into asymmetric lattice disorder at oxide interfaces using advanced microscopy and ab initio calculations, highlighting how structural factors affect defect formation.

Findings

Asymmetric oxygen vacancy formation across interfaces.

Structural differences influence vacancy formation energies.

Potential pathways to manipulate lattice disorder in oxides.

Abstract

Control of order-disorder phase transitions is a fundamental materials science challenge, underpinning the development of energy storage technologies such as solid oxide fuel cells and batteries, ultra-high temperature ceramics, and durable nuclear waste forms. At present, the development of promising complex oxides for these applications is hindered by a poor understanding of how interfaces affect lattice disordering processes and defect transport. Here we explore the evolution of local disorder in ion-irradiated La$_2$Ti$_2$O$_7$ / SrTiO$_3$ thin film heterostructures using a combination of high-resolution scanning transmission electron microscopy (STEM), position-averaged convergent beam electron diffraction (PACBED), electron energy loss spectroscopy (STEM-EELS), and \textit{ab initio} theory calculations. We observe highly non-uniform lattice disordering driven by asymmetric oxygen vacancy formation across the interface. Our calculations indicate that this asymmetry results from differences in the polyhedral connectivity and vacancy formation energies of the two interface components, suggesting ways to manipulate lattice disorder in functional oxide heterostructures.