Termination chemistry-driven dislocation structure at SrTiO3/MgO heterointerfaces

Abstract

Exploiting the promise of nanocomposite oxides necessitates a detailed understanding of the dislocation structure at the interfaces, which governs diverse and technologically relevant properties. Here we report atomistic simulations demonstrating a strong dependence of the dislocation structure on the termination chemistry at the SrTiO 3 /MgO heterointerface. The SrO-and TiO 2 -terminated interfaces exhibit distinct nearest neighbour arrangements between cations and anions, leading to variations in local electrostatic interactions across the interface that ultimately dictate the dislocation structure. Networks of dislocations with different Burgers vectors and dislocation spacing characterize the two interfaces. These networks in turn influence the overall stability of and the behaviour of oxygen vacancies at the heterointerface, which will dictate vital properties such as mass transport at the interface. To date, the observed correlation between the dislocation structure and the termination chemistry at the interface has not been recognized, and offers novel avenues for fine-tuning oxide nanocomposites with enhanced functionalities.

Regular Network of Misfit Dislocations at the BaZr0.8Y0.2O3−x/NdGaO3 Interface and Its Role in Proton Conductivity

“…This is somehow expected considering the moderate temperature at which the annealing is carried out. This phenomenon is indicative of a strongly preferential incorporation of hydroxyl groups in the core of the MDs, as predicted by recent theoretical studies . This incorporation is accompanied by absorption of protons necessary to maintain the neutrality of the electrical charge.…”

“…It was hypothesized the high values of conductivity were possibly related to the high densities of defects, mostly dislocations, at the film/substrate interface. Namely, dislocation lines can act as fast paths for diffusing atoms, similar to the pipe diffusion mechanism, which has been predicted in the case of the SrTiO 3 /MgO interface . This phenomenon is thought to originate from the disordered core region with high mobility for cation diffusion .…”

Edge dislocation slows down oxide ion diffusion in doped CeO2 by segregation of charged defects

“…Furthermore, high-resolution transmission electron microscopy examination in other materials, in particular the interface of (Nd 0.35 Sr 0.65 )MnO 3 /SrTiO 3 , demonstrated that edge-type misfit dislocations allow for interdiffusion of cations within a semicylindrical boundary around the dislocation 7 , as also predicted for the dislocations of ceria in this work. The edge dislocation modelled in this paper can be different from misfit dislocations at the thin-film/substrate interfaces due to the local structure and chemical composition 49 . However, the key driver of cation and vacancy segregation around the edge dislocations in bulk ceria studied here is the strain field, which is also present around misfit dislocations.…”

Probing Interfaces in Metals Using Neutron Reflectometry

“…By contrast, the structure of oxide/oxide or metal/oxide interfaces is much more difficult to assess. Such interfaces are often several nanometers wide [69], exhibit transitions in structure reminiscent of phase changes [8], and contain intrinsic defects with distinct local compositions [70]. NR provides several advantages for investigating such interfaces, including high depth resolution and sensitivity to composition.…”