Since the discovery of the ferroelectric and piezoelectric properties of Rochelle salt in 1920, the ferroelectric system, which has perhaps been one ot the most studied is the barium titanate (BaTiO3). The BaTiO3 presents a simple perovskite structure with excellent physical properties, such as high dielectric permittivity, high piezoelectric and pyroelectric coefficients, high mechanical stability and others. When modified with some donor and/or acceptor ions it also shows excellent semiconducting properties. In this work, the physical properties of the rare-earth modified BaTiO3 system have been investigated. High-density ceramic samples were obtained from the polymeric precursors method (PPM), well known in the current literature for its efficiency, when compared to conventional methods commonly used for obtaining ceramic materials. Structural properties were carefully analyzed from x-ray diffraction (DRX) technique and Rietveld’s refinement. The dielectric and electric properties were investigated focusing on the semiconducting properties promoted by the dopant ion. The Positive Temperature Coefficient of Resistivity (PTCR) response have been also investigated as a function of the doping element concentration. An abnormal behavior in the PTCR coefficient, suggests the amphoteric characteristics of such doping ion, which have not been reported in the current literature.
The authors would like to thank to FAPEMIG, FAPESP and CNPq Brazilian agencies for financial support. M. A. Oliveira also thanks the Materials Science Post-Graduation Program(PPGCM), UNESP, Ilha Solteira, Brazil.