Electrical properties of Nb-doped BaTiO3

This paper reports the results of the electrical conductivity measurements for Nb-doped BaTiO3 ceramics in the temperature range 1073-1373 K in both oxidizing and reducive atmospheres. The electrical conductivity was also applied to monitor the formation of Nb-doped BaTiO3. It is shown that the solid state reaction for the system BaTiO3-Nb2O3 takes place at 1573 K, but annealing at 1623 K is required to produce specimen of reproducible electrical properties. The solubility limit of Nb in stoichiometric BaTiO3 (Ba/Ti = 1) at 1573 K in air is 5 at%. The p(O-2) exponent of the electrical conductivity was determined (1/n(sigma) = -1/3.9). This exponent is consistent with the defect disorder model of Nb-doped BaTiO3 derived assuming that ionic charge compensation prevails. The activation energy of the electrical conductivity for Nb-doped BaTiO3 depends on both p(Oz) and Nb content. (C) 2001 Elsevier Science Ltd. All rights reserved.