Atomic and electronic characterization of thea[100]dislocation core inSrTiO3

The structure and chemistry of the $a[100]$ edge-dislocation core in ${\mathrm{SrTiO}}_{3}$ 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 $\mathrm{Ti}{\ensuremath{-}L}_{2,3}$ 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 ${L}_{3}{/L}_{2},$ 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.