The effect of dysprosium on the microstructure and dielectric properties of (Ba1-xSrx)TiO3 ceramics

A study was performed on the microstructure and dielectric properties of barium strontium titanate ceramics having the compositions (Ba_1-xSr_x)TiO₃, and (Ba_0.99-xSr_xDy_0.01)TiO₃ with x in the range from 0 to 0.3. In all cases, the addition of dysprosium resulted in a marked reduction in grain size, from ≈50 μm to ≈1 μm, which was accompanied by a substantial increase in permittivity below the Curie temperature. The peak in permittivity at the Curie point was strongly suppressed by Dy-doping, and the phase transition range became broad and diffuse, particularly at the higher levels of strontium. TEM (transmission electron microscope) observations of a high density of dislocations and an inhomogeneous distribution of strontium within the grains suggest that the chemical segregation of strontium is largely responsible for this diffuse phase transition behavior