Thesis (M.Sc.)--Chulalongkorn University, 1998

The effects of strontium and lead on the microstructure and dielectric properties of barium titanate were investigated. Sr decreased the grain size and the Curie temperature of BaTiO3. 10%Sr lowered the Curie temperature from 128 ํC to 95 ํC and %Sr increased to 20% and 30% the Curie temperature decreased to 62 ํC and 33 ํC, respectively. In addition, Sr increased the dielectric constant. 20%Sr doped BaTiO3 gave the highest maximum dielectric constant about 13000. Since 20%Sr-doped BaTiO3 gave the highest dielectric constant at the Curie temperature, it was selected to be base material for Pb dopant Pb increased the grain size and decreased the dielectric constant of Ba0.8Sr0.2TiO3 through the temperature range of measurement. 5%Pb increased the Curie temperature from 60 ํC to 95 ํC and % Pb increased to 10%Pb the Curie Temperature increased to 110 ํC. The maximum dielectric constant of 10%Pb-doped Ba0.8Sr0.2TiO3 is higher than that of 5%Pb-doped Ba0.8Sr0.2TiO3. An increase amount of %Pb decreased the dissipation factor