Gliding of conducting dislocations in SrTiO3 at room temperature: Why oxygen vacancies are strongly bound to the cores of dislocations

Abstract

It is well known that the presence of dislocations in solids determines their mechanical properties, such as hardness and plasticity. In the prototype transition metal oxide SrTiO3, dislocations also influence the electronic properties, as they can serve as preferential sites of reduction processes, e.g., supporting the evolution of metallic filaments upon thermal reduction. This indicates that there is a strong interaction between the dislocations and oxygen vacancies formed upon reduction. The latter are locally-compensated by electrons. In order to investigate this interaction, in this study, we analyze the influence of mechanical stress on an already-existing dislocation-based network of conducting filaments in a single crystal. We demonstrate that plastic deformation at room temperature not only modifies the arrangement of dislocations but also conductivity at the nanoscale. This indicates that there is a strong attraction between oxygen vacancies and dislocations, such that the movement of metallic filaments and dislocations under mechanical stress is inseparably coupled.

Annihilation and Generation of Dislocations by Irradiation by Ions and Electrons in Strontium Titanate Single Crystal

“…Hence, even though dislocations have traditionally been avoided in classical semiconductors due to their detrimental effects on carrier mobility and functional properties, they are proven to provide enhanced functionalities in oxides. Using mechanical stress and plastic deformation, one can increase the number of dislocations or move the existing ones [12,13]. This, in turn, can be controllable to enhance desired properties, such as electrical conductivity [14].…”