The thermal activation energies for conduction in Nb-doped SrTiO3 grains and grain boundaries were investigated by means of impedance spectroscopy. In order to observe the effect of electrode/SrTiO3 bulk interfaces, the various impedances of SrTiO3 single crystals were measured. The activation energy of an electrode/bulk interface was found to be 1.3eV, whereas that of the bulk was 0.8eV. The activation energies for a grain, a grain boundary and an electrode/bulk interface were estimated to be equal to about 0.8, 1.3 and 1.5eV, respectively. On the basis of these results, it was suggested that the activation energy of 0.8eV for the grain arose from O vacancies, while the activation energy of 1.3eV for the grain boundary arose from Sr vacancies.

Analysis of Defect Formation in Nb-Doped SrTiO3 by Impedance Spectroscopy. S.H.Kim, J.H.Moon, J.H.Park, J.G.Park, Y.Kim: Journal of Materials Research, 2001, 16[1], 192-6