Grain boundary engineering for improving conductivity of polycrystalline SrTiO₃

The present paper reports the conductivity enhancement of strontium titanate (SrTiO₃) using grain boundary engineering (GBE). In grain boundaries (GBs), Σ3 GBs have superior electrical properties to general GBs. Although many studies have focused on increasing the population of Σ3 GBs, the increase in the Σ3 GB population was limited mainly because the previous studies did not provide an efficient method for orienting grains (e.g., inhibition of abnormal grain growth). This study attempts to manipulate nanocrystal planes of SrTiO₃ starting powders by using additives of acetic acid and citric acid. Using citric acid both populations of (111) surfaces and Σ3 GB are increased. Furthermore, our conductivity measurement indicated that the higher the Σ3 GB population the more favorable the conductivity. In summary, the findings of this study opened new possibilities for increasing the conductivity of GBE.