Jialong Li

Preparation and Characterization of Ag-Doped BaTiO3 Conductive Powders

BaTiO3 powders doped with Ag at different Ag/Ba molar ratios were prepared by sol-gel method. The resistivity reached the lowest point of 5.644 Ω·m when Ag concentration was 0.10 at% and the powders were calcined for two times at 800°C and 500°C. XRD and FTIR investigations showed that no new substance was formed after the doping and calcining process, but the particle size and the strength of Ti-O bond in modified BaTiO3 crystal cell all changed. The conductivity of Ag-doped BaTiO3 powders with different Ag concentrations and through different preparing methods was discussed by using defect theory.

Preparation of PbTiO3-Based Conductive Ceramic Powders by Gaseous Penetration of Rare Earth

The new type PbTiO3 based ceramic conductive powders were prepared with a special technology, gaseous penetration, which is making rare earth La penetrate into PbTiO3 powders in the gaseous state at high temperature. Through XRD analysis, it is found that there are some new compounds such as LaTiO3 and LaTi3O49 formed after penetration of La, which indicates that the gaseous penetration made La element enter PbTiO3 powders and the complex reactions took place during the penetration process. Through SEM, it can be deduced that the rare earth elements occupied the atom vacancies, formed the new phases and made the grains of La-penetrated PbTiO3 based powders become smaller and finer with less pores and appeared as dispersing structure. All these led to a significant change in electric conductivity, and when the La3+ content in the solvent was 0.02, the penetration temperature was 950°C and the penetration time was 4h, the resistivity at room temperature was the smallest, which decreased from 8.3×108Ω.m to 8.2×10-4Ω•m.

Preparation and Characterization of Different Metal Modified BaTiO3 Powders

BaTiO3 powders modified with Sm, La, Cu, Al, Zn were prepared by solid doping and gaseous penetration method and their components, structure, superficies and electric properties were characterized. The results show that the resistivity of the modified powders is decreased after both solid doping and gaseous penetration, and it is more obviously after gaseous penetration. Among all the metals being discussed, Sm has the most significant influence on decreasing the resistivity of modified powders. The room temperature resistivity of Sm-penetrated BaTiO3 powders is the lowest, which decreases from 8.3×1010Ω•m (pure BaTiO3 powders) to 1.65×105Ω•m. SEM investigation illustrates that the powders are in uniform grain size. No apparent pores and small grains are found. XRD analysis indicates that the doping process only leads to the changes of the peak width and intensity without new phases appearing, but characteristic peaks of Sm2TiO5, SmTiO3, and Ba10.37Sm17.08Ti36O108 can be detected after gaseous penetrated, which leads to the decrease of the resistivity of modified BaTiO3 powders.