The Effect of Aliovalent Cations (Nb5+ and La3+) on the Electrical Characteristics of BaTiO3 Based Ceramics

The effects of Nb/Mn and La/Mn on the electrical properties of doped BaTiO3 ceramics were investigated in this paper. A series of Nb/Mn and La/Mn-doped BaTiO3 samples, with dopant concentrations, ranged from 0.1 up to 2 at% of La and Nb, were prepared. The Mn concentration of 0.01at% was the same in all samples. The samples have been sintered at 1300°C for two hours. SEM analysis indicated a fine-grained microstructure with grain size less than in La/Mn-BaTiO3. For the same concentration of additives, the bimodal microstructure was observed in Nb/Mn-BaTiO3. Samples with a low concentration of additives (0.1 and 0.5at%) show a higher dielectric constant value. A stable dielectric permittivity with a flat dielectric response in the transition zone is observed in high doped ceramics. Higher dielectric constant values were measured for samples doped with Nb and ranged from 1790 to 4027 at room temperature. The shift of Curie temperature towards lower temperature has been noticed in all samples. The Curie-Weiss law was used to analyze the permittivity behavior in the paraelectric region.