Dielectric tunability of (Ba[sub 0.90]Ca[sub 0.10])(Ti[sub 0.75]Zr[sub 0.25])O₃ ceramics

Abstract

We have performed a study on the dielectric properties of (Ba[sub 0.90]Ca[sub 0.10])(Ti[sub 0.75]Zr[sub 0.25])O₃ bulk ceramics prepared by a sol-gel technique in the cooling temperature range from 400 to 213 K. The ceramics are found to exhibit an interesting dielectric response under the presence of a dc bias field. The field dependence of dielectric constant is stronger at T≈T[sub m] (T[sub m] is the temperature of dielectric maximum) and the field-induced variation of dielectric constant Δε is nonzero for T-T[sub m]<150 K. One striking feature of these ceramics is that they possess a broad optimum value of figure of merit (as high as 200 at 30 kV/cm) between the temperature range from 295 and 330 K. At room temperature, the high tunability (K=60%), low-loss tangent (≈0.003), and large figure of merit (200), clearly indicate that these ceramics are suitable candidates for microwave applications.