Dislocation dissociation and stacking-fault energy calculation in strontium titanate

The dislocation microstructure of strontium titanate plastically deformed below room temperature shows dipolar configurations of a〈1 1 0〉 screw dislocations. The dipole height is so small that dipole annihilation is expected. Here we show why this is inhibited. By high-resolution transmission electron microscopy observations we find that in such dipoles each dislocation is dissociated into two collinear a/2〈1 1 0〉 partials on a {1 1 0} plane. Elasticity theory calculations provide a stacking-fault energy value of 340 ± 90 mJ m−2. Finally, we discuss the effects of this dissociation process on the mechanical behaviour.