The solid solution Ba Sr TiO (BSTO) displays dielectric response that is highly tunable, while also exhibiting low losses in a broad frequency regime, including the microwave band. Therefore, there is a need for a better understanding of the influence of the BSTO microstructure on its relaxor properties and performance in a variety of technological applications. Since the local polarization in BSTO is strongly dependent on composition, so is its response to an applied AC field. In this work, we have adopted a phase field method to study the frequency-dependent dielectric response of this system while accounting for the local fluctuations in the solid-solution composition. By utilizing a thermodynamic potential that includes spatial dependence on the averaged Sr content, we connected relaxor-like features in the dielectric dispersion to local spatial inhomogeneities, such as average size of Sr- or Ba-rich regions, across a wide range of temperatures. These results show that the adopted simple coarse-grained approach to the relaxor problem is sensitive enough to reveal correlations between the frequency and temperature dependence of the dielectric response and modulations in the material morphology and microstructure.
Modeling structure–properties relations in compositionally disordered relaxor dielectrics at the nanoscale
Ashok Gurung, John Mangeri, Aaron M. Hagerstrom, Nathan D. Orloff, S. Pamir Alpay, Serge Nakhmanson; Modeling structure–properties relations in compositionally disordered relaxor dielectrics at the nanoscale. J. Appl. Phys. 14 September 2023; 134 (10): 104102. https://doi.org/10.1063/5.0160448
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