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The complex-oxides interfaces hold rich physics that have resulted in the emergence of various novel functional properties. While strain engineering has been widely used to induce many properties over the past decade, more recently the role of oxygen vacancies has increasingly drawn wider attention. In particular, research has revealed that there exists a strong coupling between strain and oxygen vacancy formation energy. This coupling can be used to alter oxygen vacancy concentration at interfaces, thereby opening another degree of freedom to control interfacial properties. In this review, we highlight recent works that have interrogated the connection between coupling and the emerging interfacial properties. The coupling has not only been used to selectively create oxygen vacancies at specific crystallographic oxygen sites but has also been used to manipulate ordering of oxygen vacancies near interfaces. In addition, recent studies have extended the existing connection between strain and octahedra distortion to oxygen vacancies, where the role of vacancies in the properties emerging due to octahedra distortion is now being unveiled. Finally, we discuss recent data-science efforts in the design and discovery of complex oxides and property prediction. [ABSTRACT FROM AUTHOR]

Oxygen vacancies are found to play a crucial role in inducing many functional properties at the heterointerfaces in complex oxides. Gaining better control over the properties requires an understanding of the atomic structure of oxygen vacancies at the heterointerfaces. In this paper, we elucidate the effects of the interfacial strain on the oxygen-vacancy ordering in fluorite δ-Bi2O3 and perovskite LaNiO2.5 using first-principles calculations. By applying biaxial strains, we find that the 〈110〉−〈111〉 oxygen vacancy order in δ-Bi2O3 is broken, resulting in a faster diffusion of oxygen ions. Similarly, the biaxial strain is used to leverage both ordered and disordered arrangements of vacancies in LaNiO2.5. Besides the vacancy order, we find that the biaxial strain can also be used to break the cation order in Gd2Ti2O7, where Gd and Ti antisites can be created on the cation sublattice, which leads to enhanced radiation tolerance and higher oxygen diffusivity. These results indicate that the biaxial strain that is commonly present at heterointerfaces can be used to gain control over both ordered and disordered arrangements of defects, potentially opening new opportunities to functionalize complex oxides. [ABSTRACT FROM AUTHOR]

Recent irradiation experiments on concentrated random solid solution alloys (CSAs) show that some CSAs can undergo disorder-to-order transition, i.e., the atoms that are initially randomly distributed on a face centered cubic crystal lattice undergo ordering (e.g., L10 or L12) due to irradiation. In this work, we elucidate that the atomic structure could affect the segregation properties of grain boundaries. While working on Ni and Ni-Fe alloys, from static atomistic simulations on 138 grain boundaries, we show that despite identical alloy composition, Cr segregation is higher in the disordered structures compared to ordered structures in both Ni0.50Fe0.50 and Ni0.75Fe0.25 systems. We also show that grain boundary (GB) energy could act as a descriptor for impurity segregation. We illustrate that there is a direct correlation between Cr segregation and grain boundary energy, i.e., segregation increases with the increase in the GB energy. Such correlation is observed in pure Ni and in the Ni-Fe alloys studied in this work. [ABSTRACT FROM AUTHOR]