DEFECT CHEMISTRY OF DONOR-DOPED AND UNDOPED STRONTIUM-TITANATE CERAMICS BETWEEN 1000-DEGREES AND 1400-DEGREES-C

The electrical conductivity, sigma, of donor-doped and undoped stronti um titanate (SrTiO3) ceramics and, in some cases, single crystals, Sr1 -xLaxTiO3 (0 less than or equal to x less than or equal to 0.1), was i nvestigated in the temperature range of 1000 degrees-1400 degrees C un der oxygen partial pressures, P-O2, Of 10(-20)-1 bar, In conjunction w ith Hall data and thermopower data from related papers, a set of const ants for a defect-chemical model was determined, precisely describing point-defect concentrations and transport properties of these material s, In contrast to former works, temperature-dependent transport parame ters and their non-negligible influence on the determination of the co nstants was considered, as well as the equilibrium restoration phenome na of the cation sublattice, which can be studied only at such high te mperatures, It was shown that defects in the cation sublattice complet ely govern the electrical behavior of donor-doped and undoped SrTiO3. In the latter case, frozen-in strontium vacancies act as intrinsic acc epters, determining the sigma(P-O2) curves at lower temperatures, This intrinsic acceptor concentration also can be calculated with this mod el, The very good agreement between calculation and measurement is sho wn in many examples.