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 o xidizing and reducive atmospheres. The electrical conductivity was also app lied to monitor the formation of Nb-doped BaTiO3. It is shown that the soli d state reaction for the system BaTiO3-Nb2O3 takes place at 1573 K, but ann ealing 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 conducti vity 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 c harge compensation prevails. The activation energy of the electrical conduc tivity for Nb-doped BaTiO3 depends on both p(Oz) and Nb content. (C) 2001 E lsevier Science Ltd. All rights reserved.