Superior energy storage BaTiO3-based amorphous dielectric film with polymorphic hexagonal and cubic nanostructures

Abstract

• Constructing nanocrystal in the amorphous structured BT based film is proposed. • Coexistence structures simultaneously improve energy density and efficiency. • Building a three-dimensional model to help understand the coexistence mechanism. • Hexagonal/cubic BT based nanocrystal structure contribute to BDS and polarization. • Mn dopant in the 0.94BT-0.06BZZ thin film has superior energy storage performance. An effective route to improve the energy storage performance by constructing polymorphic nanostructures in (1-x)BaTiO 3 -xBi(Zn 1/2 Zr 1/2 )O 3 (BT-BZZ) films was proposed. The finite element simulation method was used to simulate the impacts of amorphous/crystalline phase and volume fraction on the electric field and polarization distributions. Together with the experimental observation, it is confirmed that an appropriate amorphous/crystalline structure volume fraction is conducive to the energy storage properties. Of particular significance is that Mn dopant in the 0.94BT-0.06BZZ films induces hexagonal BT phase with higher polarization compared with that of cubic phase, leading to a high energy density of 85 J/cm 3 and greatly improved energy efficiency of 84% in 3Mn-0.94BT-0.06BZZ film. The existence of the amorphous structure and local polymorphic hexagonal/cubic nanostructures is confirmed by the aberration-corrected scanning transmission electron microscopy, which synergistically contribute to the greatly enhanced energy storage properties, providing a new design paradigm for high performance dielectric materials.