Microstructure and dielectric characteristics of (PbxBa0.5-xSr0.5)TiO3 ceramics

Microstructural and dielectric properties of the PbxBa0.5-x-Sr0.5TiO3 system have been studied, It is found that this system forms a solid solution in the entire composition range (0.01 less than or equal to x less than or equal to 0.5) and is cubic for the x = 0, 0.1, and 0.2 compositions and tetragonal for other compositions, Measurements of the dielectric constant as a function of temperature reveal that this material is ferroelectric at room temperature for the x > 0.2 compositions and has a broad paraelectric-ferroelectric transition region, No shift in the dielectric maxima was noted; however, there is a slight spread in the dielectric constant with frequency for the x = 0.4 composition, A quantitative model to mathematically analyze the effect of composition fluctuations on the dielectric broadening for a ternary system is presented, Transmission electron microscopic studies reveal the presence of 90 degrees ferroelectric domains oriented along the {01(1) over bar} planes for the x = 0.3 and 0.4 compositions.