The structure and electrical properties of a symmetrical 5.4° [001] tilt grain boundary in Fe-doped material were investigated by means of transmission electron microscopy and impedance spectroscopy, respectively. In weak-beam dark-field images, the grain boundary was seen to consist of a periodic array of dislocations. High-resolution transmission electron microscopic images showed that the dislocation cores were separated by regions of strained lattice. The impedance response of the bicrystal was measured at 20Hz to 1MHz, as a function of temperature and O partial pressure. It was noted that the transport of charge across the array of dislocations that formed the grain boundary was strongly hindered. An analysis of the impedance data in terms of a double Schottky-barrier model yielded a space-charge potential that exhibited a weak dependence upon temperature and O partial pressure. It was equal to about 0.55V in the investigated regime.

Electrical and Structural Characterization of a Low-Angle Tilt Grain Boundary in Iron-Doped Strontium Titanate. R.A.De Souza, J.Fleig, J.Maier, O.Kienzle, Z.Zhang, W.Sigle, M.Rühle: Journal of the American Ceramic Society, 2003, 86[6], 922-8