High-Throughput Prediction of Thermodynamic Stabilities of Dopant-Defect Clusters at Misfit Dislocations in Perovskite Oxide Heterostructures

Abstract

Complex oxide heterostructures and thin films have emerged as promising candidates for diverse applications, wherein interfaces formed by joining two different oxides play a central role in novel properties that are not present in the individual components. Lattice mismatch between the two oxides leads to the formation of misfit dislocations, which often influence vital material properties. In oxides, doping is used as a strategy to improve properties, wherein inclusion of aliovalent dopants leads to formation of oxygen vacancy defects. At low temperatures, these dopants and defects often form stable clusters. In semicoherent perovskite oxide heterostructures, the stability of such clusters at misfit dislocations, while not well understood, is anticipated to impact interface-governed properties. Herein, we report atomistic simulations elucidating the influence of misfit dislocations on the stability of dopant-defect clusters in SrTiO 3 /BaZrO 3 heterostructures. SrO−BaO, SrO−ZrO 2 , BaO−TiO 2 , and ZrO 2 −TiO 2 interfaces having dissimilar misfit dislocation structures were considered. High-throughput computing was implemented to predict the thermodynamic stabilities of 275,610 dopant-defect clusters in the vicinity of misfit dislocations. The misfit dislocation structure of the given interface and corresponding atomic layer chemistry play a fundamental role in influencing the thermodynamic stability of geometrically diverse clusters. A stark difference in cluster stability is observed at misfit dislocation lines and intersections as compared to the coherent terraces. These results offer an atomic scale perspective of the complex interplay between dopants, point defects, and extended defects, which is necessary to comprehend the functionalities of the perovskite oxide heterostructures.

High-throughput prediction of oxygen vacancy defect migration near misfit dislocations in SrTiO3/BaZrO3 heterostructures

“…The primary reason to place dopants in pairs at nearest neighbors to the oxygen vacancy is that this configuration was found to be most favorable energetically at misfit dislocations in STO/BZO heterostructures. 70 Activation energies for oxygen vacancy migration are depicted via arrows pointing in a particular jump direction and their colors indicate the absolute magnitude given in the respective energy scale. The activation energies reported in this work are a bit higher in magnitude, especially near misfit dislocations.…”

“…A usual critique of the methodology based on interatomic potentials used in this work is that they are unsuitable for chemical environments for which they are not fitted, such as interfaces and transition states for migration barrier calculations. However, it is important to note that we have rigorously tested the methodology implemented in this work and successfully utilized it to understand the thermodynamics and kinetics of defects at interfaces, 29,54,55,60,69,70 surfaces, 71,72 steps, 56,73 and grain boundaries [74][75][76] in complex oxides. In addition, we have effectively used this methodology to study structureproperty relationships at misfit dislocations, as well as computed migration barriers in an intricate chemical environment.…”

Combined Theoretical and Experimental Study of the Moiré Dislocation Network at the SrTiO3-(La,Sr)(Al,Ta)O3 Interface

“…Given that the oxide defect chemistry and diffusion are known to be heavily affected by strain − and since dislocations are surrounded by strong strain fields, one would expect preferential defect formation and segregation around dislocations. Indeed, recent computational studies have focused not only on describing the structure of interfacial misfit dislocations , but also on their interaction with dopants, defects, and defect clusters. − These classical potential-based calculations, however, always treat charged point defects since whole ions are removed. Electronic structure density functional theory (DFT) calculations would be necessary to account for the formation of neutral or not fully ionic defects.…”

“…Indeed, recent computational studies have focused not only on describing the structure of interfacial misfit dislocations 18 , 19 but also on their interaction with dopants, defects, and defect clusters. 20 − 22 These classical potential-based calculations, however, always treat charged point defects since whole ions are removed. Electronic structure density functional theory (DFT) calculations would be necessary to account for the formation of neutral or not fully ionic defects.…”