Nonlinear dielectric properties of amorphous Bi1.8Pb0.3Sr2Ca2Cu3−x KxOz (x = 0.2–0.3)

The dielectric constant of amorphous Bi_1.8Pb_0.3Sr₂Ca₂Cu_3?x K_xO_x (x = 0.2–0.3) is measured as a function of the static electric field strength. It is found that, as the field strength increases, the dielectric constant decreases following a quadratic law. This behavior of the dielectric constant in a static electric field indicates nonlinear dielectric properties, which can be described within the thermodynamic theory of ferroelectricity.