Hierarchical heterostructure design to enhance energy storage properties of ferroelectric films at different electric fields

Abstract

Polarization and breakdown strength as two sides of one coin are difficult to balance in one dielectric material, and so hierarchical heterostructure would be a good way to combine the advantages of each material enhancing energy density. In this work, high polarization Bi(Mg0.5Zr0.5)O3 (BMZ) and high breakdown strength Ba(Zr0.25Ti0.75)O3 (BZT) are chosen to prepare 1BMZ/4BZT/1BMZ (Type-A), 3BMZ/3BZT (Type-B) and 3(BMZ/BZT) (Type-C) hierarchical heterostructures thin films on Pt/Ti/SiO2/Si substrate via sol-gel method. Microstructure characteristics of thin films indicate that they possess well density, no crack and smooth surface. Thin films with Type-B structure possess a high dielectric constant of ∼500, which exceeds ∼150 of that with Type-A and Type-C structures. For energy storage properties, Type-B and Type-C thin films achieve high recoverable energy density Wrec of 85.6 J/cm3 and 85.7 J/cm3 at low field of 2545 kV/cm and high field of 4980 kV/cm, respectively. The design of hierarchical heterosrtucture would break the limitation of low energy density in single material, and provide a new thinking for the applications of dielectric energy storage materials.