The effect of dysprosium on the microstructure and dielectric properties of (Ba/sub 1-x/Sr/sub x/)TiO/sub 3/ ceramics

A study was performed on the microstructure and dielectric properties of barium strontium titanate ceramics having the compositions (Ba/sub 1-x/Sr/sub x/)TiO/sub 3/, and (Ba/sub 0.99-x/Sr/sub x/Dy/sub 0.01/)TiO/sub 3/ 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 approximately=50 mu m to approximately=1 mu m, 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.<
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