Ferroelectric properties of compositionally graded BST ceramics

Homogeneous and graded Ba_{1? x} Sr _x TiO₃ ceramics were produced by thick-film technique (tape casting). In the graded materials, the content of strontium was changed from 0 to 30 mol% in the direction normal to the surface. The microstructure, Ba/Sr spatial distribution, polarization characteristics, and dielectric properties of the samples were investigated. No hysteresis loop offset (neither along E- nor P-axis) in the graded Ba_{1? x} Sr _x TiO₃ structures (x = 0–0.3) was observed. This fact was analyzed on the basis of phenomenological models for graded ferroelectrics. The materials with spatially changing composition were characterized by high-temperature stability of dielectric properties and low temperature coefficient of capacitance.