Percolative properties in ferroelectric-dielectric composite ceramics

Abstract

Percolative properties in dielectric (DE) tunability were observed in three ferroelectric (FE)-DE composite ceramics as follows: xBa0.5 Sr 0.5 TiO3 -MgO, xBa0.4 Sr0.6 TiO 3 - Mg2 TiO4, and xBa0.5 Sr0 .5 TiO3 - Mg3 B2 O6. Dielectric constants of the composites increased monotonously with increasing volume fractions of FE component. Comparatively, their DE tunabilities exhibited a weak dependence on FE concentrations over a wide range. However, their tunabilities started to decrease substantially below a critical concentration of FE. The critical concentrations were 40 vol % for Ba0.5 Sr 0.5 TiO3 -MgO, 38 vol % for Ba0.4 Sr 0.6 TiO3 - Mg2 TiO4, and 33 vol % for Ba0.5 Sr0.5 TiO3 - Mg3 B 2 O6. These results could be used as a guide to tailor the properties of FE-DE composites for tunable device applications. © 2010 American Institute of Physics.