Abstract
Vertically aligned nanocomposite (VAN) films have self-assembled pillar-matrix nanostructures. Owing to their large area-to-volume ratios, interfaces in VAN films are expected to play key roles in inducing functional properties, but our understanding is hindered by limited knowledge about their structures. Motivated by the lack of definitive explanation for the experimentally found enhanced ionic conductivity in Sm-doped-CeO2/SrTiO3 VAN films, we determine the structure at vertical interfaces using random structure searching and explore how it can affect ionic conduction. Interatomic potentials are used to perform the initial searching, followed by first-principles calculations for refinement. Previously unknown structures are found, with lower energy than that of an optimized hand-built model. We find a strongly distorted oxygen sublattice which gives a complex landscape of vacancy energies. The cation lattice remains similar to the bulk phase, but has a localized strain field. The excess energy of the interface is similar to that of high angle grain boundaries in SrTiO3.
Highlights
Oxide thin films have a wide range of applications in electronic, magnetic, and energy devices
We study the interfaces in Vertically aligned nanocomposite (VAN) films consisting of Sm-doped-CeO2(20 at. %) pillars embedded in a matrix of SrTiO3
An I4/mcm phase of STO is found to have the lowest energy using density functional theory (DFT) for relaxation which is consistent with the low temperature phase of STO found experimentally
Summary
Oxide thin films have a wide range of applications in electronic, magnetic, and energy devices. Aligned nanocomposite (VAN) films are a new form of thin film material which contain nanopillars of one phase embedded in a matrix of another. Because of unique strain states, uniform strain, large area of interfaces, and perfectly clean interfaces in these structures, they have been attracting a lot of interest for a wide range of functional systems.. VAN structures are easy to fabricate compared to planar superlattice films—they grow by self-assembly from a single target material using pulsed laser deposition, and the density of interfaces is very high with nanopillars of sizes around 10–20 nm. The local environment at an interface can be very different from that of the bulk material, which leads to reconstruction of the atomic and electronic structures. The advancement in scanning transmission electron microscopy (STEM) has allowed individual atomic columns to be imaged, determining the local structures often still requires extensive simulations and sometimes intuition
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
