Multiphase Engineered BNT-Based Ceramics with Simultaneous High Polarization and Superior Breakdown Strength for...

Area of Science:

• Materials Science
• Ceramics Engineering
• Energy Storage

Background:

• Dielectric ceramics are vital for high-temperature, pulse-power energy storage.
• A key challenge is the trade-off between polarization and breakdown strength.
• Simultaneously enhancing both properties is crucial for advanced applications.

Purpose of the Study:

• To develop a dielectric ceramic with simultaneously high polarization and breakdown strength.
• To investigate the effect of sintering heating rate on ceramic phase composition and microstructure.
• To optimize dielectric properties for pulse-power energy storage.

Main Methods:

• Multiphase engineering of 0.8(0.95Bi_0.5Na_0.5TiO₃-0.05SrZrO₃)-0.2NaNbO₃ (BNTSZNN) ceramics.
• Two-step sintering with controlled heating rates.
• First-principles calculations to understand polarization mechanisms.
• Microstructural analysis (grain size, phase composition).
• Electrical property measurements (polarization, breakdown strength, discharge energy density, discharge speed).

Main Results:

• A fast heating rate (60 °C/min) promoted the rhombohedral (R) phase and finer grain size.
• Increased R phase proportion enhanced overall polarization (up to 43 μC/cm²).
• Finer grain size improved breakdown strength (up to 350 kV/cm).
• Achieved ultrahigh discharge energy density (W_dis) of 5.55 J/cm³ and efficiency (η) > 85%.
• Excellent temperature stability (<10% variation from RT to 160 °C) and ultrafast discharge (τ_0.9 ≈ 60 ns).

Conclusions:

• Multiphase engineering via controlled sintering heating rates effectively resolves the polarization-breakdown strength limitation in dielectric ceramics.
• BNTSZNN ceramics exhibit exceptional energy storage performance and stability, suitable for demanding pulse-power applications.
• The study provides a pathway for designing advanced dielectric materials for next-generation energy storage systems.