Atomic and electronic characterization of the a[100] dislocation core in SrTiO₃

The structure and chemistry of the a[100] edge-dislocation core in SrTiO₃ was investigated by high-resolution transmission electron microscopy and electron-energy-loss spectroscopy. The dislocation core is found to be compact, with only a slight dissociation on the {100} plane. This indicates that the {100} antiphase boundary energy is high. The shapes of the Ti-L_2,3 edge and the oxygen K edge slightly change in the dislocation core with respect to the bulk. In the core, the crystal-field splitting is decreased by 0.2–0.4 eV while the L₃/L₂, the Ti/O, and the e_g/t_2g intensity ratios are increased. Structure models are proposed that exhibit a charged, oxygen-deficient dislocation core. This is in good accord with previous plasticity experiments and impedance spectroscopy measurements.