Dissociation of grain boundary dislocations in SrBi₂Ta₂O₉ ferroelectric thin films

Abstract

In this work, the dissociation of grain boundary dislocations (GBDs) is reported in SrBi2Ta2O9 (SBT) ferroelectric thin films with c-axis orientation grown by pulsed-laser deposition on Pt/TiO2/SiO2/Si(100) substrates. Small-angle (8.2°) [001] tilt grain boundaries with a boundary plane close to the (110) plane exhibit partial GBDs separated by stacking faults. The dissociated grain-boundary structures have twice the number of GBDs and interdislocation core channel width smaller than that Frank's geometrical rule predicts. At the equilibrium, the repulsive elastic force between partial dislocations is balanced by an attractive force produced by the formation of a stacking fault between the partials. Based on this, the stacking fault energy is evaluated to be 0.27-0.29 J/m2. The relationship between the leakage current of SBT films and dissociation of GBDs is also discussed.