Electrical transport properties ofn-type BaTiO3

The electrical transport properties of BaTi${\mathrm{O}}_3$ are discussed against the background of recent defect-chemistry investigations and in the light of the small-polaron nature of the charge carriers. Seebeck-effect measurements and chemical investigations on highly doped BaTi${\mathrm{O}}_3$:La ceramics are also reported. It was found for BaTi${\mathrm{O}}_3$ that the dissociation energy required to set the conduction electrons free from their donor centers and also the kinetic-energy term of the small polarons contributing to the thermopower can be treated as negligible quantities.