High-Entropy Engineered (Bi_0.2Na_0.2Ba_0.2K_0.2La_0.2)TiO₃-xCa(Hf_0.7Zr_0.3)O₃ Lead-Free Ceramics for Superior Energy...

Area of Science:

• Materials Science
• Solid State Chemistry
• Energy Storage

Background:

• Dielectric ceramics are crucial for pulsed power capacitors due to high power density.
• Limited energy storage performance (ESP) hinders broader applications of current dielectric ceramics.
• High-entropy design offers a promising strategy to enhance ESP in lead-free ceramics.

Purpose of the Study:

• To develop lead-free (Bi_0.2Na_0.2Ba_0.2K_0.2La_0.2)TiO₃-xCa(Hf_0.7Zr_0.3)O₃ high-entropy ceramics (BNBKLT-xCHZ HECs).
• To investigate the effect of synergistic high-entropy design on energy storage performance.
• To achieve enhanced ESP for advanced dielectric energy storage capacitors.

Main Methods:

• Preparation of a series of BNBKLT-xCHZ HECs via a synergistic high-entropy design.
• Characterization of structural and dielectric properties.
• Evaluation of energy storage performance, including recoverable energy density (W_rec), efficiency (η), breakdown strength (BDS), frequency and temperature stability, fatigue resistance, and discharge time.

Main Results:

• BNBKLT-0.15CHZ ceramics exhibited high configurational entropy (ΔS_config ≈ 2.16 R).
• Achieved ultrahigh W_rec of ∼6.77 J/cm³ and η of ∼86% in BNBKLT-0.15CHZ.
• Enhanced ΔS_config led to reduced grain size and improved BDS (up to ∼485 kV/cm).
• Excellent frequency stability (<3.2%), temperature stability (<6.4%), fatigue resistance (<4.0%), and ultrafast discharge time (∼79 ns) were observed.

Conclusions:

• The synergistic high-entropy design effectively enhances the energy storage performance of lead-free ceramics.
• BNBKLT-0.15CHZ HEC demonstrates significant potential for advanced dielectric energy storage capacitors.
• This work provides a pathway for developing high-performance, environmentally friendly dielectric materials.