High Energy Storage Performance in BiFeO₃-Based Lead-Free High-Entropy Ferroelectrics

Area of Science:

• Materials Science
• Solid State Chemistry
• Energy Storage Materials

Background:

• Dielectric capacitors are crucial for electrical systems, demanding high energy storage capabilities.
• Existing lead-free dielectric materials often face limitations in comprehensive energy storage performance.
• The high-entropy strategy presents a promising avenue for designing advanced functional materials.

Purpose of the Study:

• To design and fabricate a novel single-phase homogeneous high-entropy ceramic.
• To investigate the structure-property relationships governing energy storage in this new material.
• To achieve superior comprehensive energy storage properties in a lead-free dielectric.

Main Methods:

• Fabrication of a single-phase homogeneous high-entropy ceramic with the composition (Bi_0.5Ba_0.1Sr_0.1Ca_0.2Na_0.1)(Fe_0.5Ti_0.3Zr_0.1Nb_0.1)O₃.
• Characterization of the material's hierarchical heterostructure, including multiphase nanoclusters and oxygen octahedral tilt.
• Evaluation of dielectric properties, energy storage density (W_rec), efficiency (η), and discharge rate (t_0.9).

Main Results:

• The high-entropy strategy resulted in a hierarchical heterostructure with unique nanoclusters and disordered oxygen octahedral tilt.
• This structure led to enhanced dielectric relaxation, diffused phase transition, and improved breakdown field.
• A giant recoverable energy density (W_rec ≈13.3 J cm^-3) and high efficiency (η ≈78%) were achieved at 66.4 kV mm^-1, alongside an ultrafast discharge rate (t_0.9 = 18 ns) and good temperature stability.

Conclusions:

• The developed lead-free high-entropy ceramic exhibits outstanding comprehensive energy storage performance, surpassing existing BiFeO₃-based materials.
• The hierarchical heterostructure and unique structural features are key to achieving these enhanced properties.
• This work offers a viable strategy for creating high-performance dielectric materials for advanced energy storage applications.