UNDERSTANDING OF DIELECTRIC PROPERTIES OF Pb_0.2Sr_0.8TiO₃-MgO COMPOSITE FROM NUMERICAL APPROACH

ABSTRACT

(Sr_0.8Pb_0.2)TiO₃-MgO composite system has been studied by Somiya et al. At room temperature, attractive relative permittivities (over 100) were obtained with an addition of MgO in (Sr_0.8Pb_0.2)TiO₃. At the same time, low relative dielectric losses, tan(δ), in the range of 10^{− 4} to 10^{− 3} were observed in the frequency range from kHz to 4 GHz, respectively. In this study, finite element method with Monte Carlo simulation is conducted for the composition x (Sr_0.8Pb_0.2)TiO₃: (1−x) MgO from x = 0 to 1 in the paraelectric phase (from −50°C to 200°C), and the results are computed and compared with the experimental data. The temperature dependence of the relative permittivity of composites was well predicted up to 35.5% volume fraction of (Sr_0.8Pb_0.2)TiO₃. The simulation results show little discrepancy as MgO volume fraction increases. Several possible factors resulting in the differences between experimental results and simulations are discussed.

ACKNOWLEDGMENTS

This work has been supported by the National Science Foundation under grant DMR-0407462

Notes

∗The linear fits of the modeled reciprocal susceptibilities were performed for temperature between 100°C and 200°C with the best linear fits.

∗∗Unrealistic values. The linear fits were based on the assumption of the composites preserve their ferroelectric behavior in which 82% of MgO is almost linear dielectric.

^†Computed values extracted from very broad dielectric maxima.