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Ultrahigh–energy density lead-free dielectric films via polymorphic nanodomain design

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Science  09 Aug 2019:
Vol. 365, Issue 6453, pp. 578-582
DOI: 10.1126/science.aaw8109

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Ultrahigh energy density dielectric film

Dielectrics help hold charge as capacitors and are fundamental energy storage components. Improving energy density and other properties may help these materials be more competitive with batteries for energy storage applications. Pan et al. introduced a specific type of nanodomain structure in a BiFeO3-BaTiO3-SrTiO3 solid solution that dramatically increased the energy density. The nanodomains were organized so as to minimize energy loss during polarization switching. The enhancement in the dielectric properties suggests that the strategy may be useful for designing high-performance dielectrics.

Science, this issue p. 578

Abstract

Dielectric capacitors with ultrahigh power densities are fundamental energy storage components in electrical and electronic systems. However, a long-standing challenge is improving their energy densities. We report dielectrics with ultrahigh energy densities designed with polymorphic nanodomains. Guided by phase-field simulations, we conceived and synthesized lead-free BiFeO3-BaTiO3-SrTiO3 solid-solution films to realize the coexistence of rhombohedral and tetragonal nanodomains embedded in a cubic matrix. We obtained minimized hysteresis while maintaining high polarization and achieved a high energy density of 112 joules per cubic centimeter with a high energy efficiency of ~80%. This approach should be generalizable for designing high-performance dielectrics and other functional materials that benefit from nanoscale domain structure manipulation.

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