Significant modification to Bi-doped BaTiO₃ by Sm in gaseous penetration process

Gaseous penetration technique was adopted to improve the electrical conductivity of pure BiTiO₃ powders and Bi-doped BiTiO₃ (BBT) powders and gel precursors, which were all prepared by sol-gel method. The effects of Sm-penetration on the structure and electrical conductivity of BBT powders and gel precursors were investigated. It was observed that Sm-penetration had a very significant influence in decreasing the resistivity of the BaTiO₃ based materials, especially for Sm-penetrated BBT gel precursors (SBBT-G) whose resistivity can reach to the lowest point of 2.15 Ωm. The dielectric properties of the BaTiO₃ based materials has been investigated and revealed that dielectric constant of SBBT-G was negative while the dielectric loss increased to an extremely high value which was distinguished from Sm-penetrated BBT powders (SBBT-P). The temperature dependence of resistivity (R-T) of SBBT-P and SBBT-G was found to obey the Arrhenius law with activation energy calculated, respectively. These results together with the resistivity and frequency (R-F) relationship curve have shown the metallization transition of SBBT-G is obvious, which has a promising applied future. Through X-ray diffraction and Scanning electron microscope, we detected that all BaTiO₃ based materials presented typical perovskite structure and the average grain size of SBBT-G was smaller and more uniform than that of SBBT-P.