Dielectric tunable performance of (BaxCa1-x)(Zr0.2Ti0.8)O3 ceramics investigated using Landau-Devonshire theory

Abstract

In this study, we investigated the dielectric tunable performance of (BaxCa1-x)(Zr0.2Ti0.8)O3 ceramics (x = 0.95, 0.91 and 0.87) using Landau-Devonshire theory. According to the dielectric constant-temperature (ε-T) curves, the Curie temperature is found to be 15.0 °C, 5.0 °C and 2.5 °C for x = 0.95, 0.91 and 0.87, respectively. It indicates that all the prepared ceramics possess a low loss tangent (tanδ) at room temperature, which is in favor of achieving a high figure of merit (FOM) and commutation quality factor (CQF). For a better understanding of the dielectric tunable performance, the Landau-Devonshire theory is used. The associated Landau coefficients have been derived based on the ε-T and tunability-electric field (k-E) curves. According to the calculated free energy-electric field and polarization-electric field curves, the prepared ceramics are in the paraelectric phase at room temperature, which is in accord with the ε-T curves. Meanwhile, the calculated results indicate that a high dielectric constant is obtained in the (Ba0.91Ca0.09)(Zr0.2Ti0.8)O3 ceramic at room temperature. Owing to the high ε and low tanδ, a high value of FOM and CQF are obtained in the (Ba0.91Ca0.09)(Zr0.2Ti0.8)O3 ceramic at ~740 kV/m. The high value of FOM (197.7) and CQF (43130) indicates that the (Ba0.91Ca0.09)(Zr0.2Ti0.8)O3 ceramic has a potential application in tunable devices.