Enhanced temperature stability of dielectric permittivity and energy storage properties of BNT-based lead-free relaxor ceramics

초록

With the rapid advancement of pulsed power technology, electrostatic capacitors that exhibit both excellent energy storage performance and thermally stable dielectric permittivity are highly desirable in the electronic industry. Addressing these needs, this work incorporated SmMg0.5Sn0.5O3 into the Bi0.47Na0.376K0.094Ba0.06Ti0.97Zr0.03O3 system ((1-x)Bi0.47Na0.376K0.094Ba0.06Ti0.97Zr0.03O3-xSmMg0.5Sn0.5O3) to disturb the ferroelectric order, resulting in the formation of dynamic polar nano regions (PNRs). The modified specimens demonstrated relaxor feature in their polarization versus field (P-E) and current density versus field (J-E) curves, leading to reduced polarization hysteresis, enhanced energy storage density (Wr), and improved efficiency (η). Under a 170 kV/cm field at x = 0.10, a Wr of 1.53 J/cm3 and η of 75.87 % were achieved at room temperature. This performance was accompanied by good thermal stability across the range of 25–145 °C, achieving a Wr of ∼1.02 J/cm3 and η of ∼88.31 % at 130 kV/cm field at the temperature of 145 °C. Relative dielectric permittivity versus temperature plots presented two suppressed anomalies, leading to significantly enhanced thermal stability of permittivity. Ceramics with x = 0.10 and 0.25 exhibited dielectric permittivity stability in the temperature ranges of 68–458 °C and 25–530 °C with a variation of ±15 %, respectively. Additionally, the x = 0.10 specimen showed fatigue-free properties in polarization versus electric field and maintained energy storage characteristics over 105 cycles. HRTEM analysis confirmed the presence of a few nano-domains and several PNRs (∼4–7 nm) along with the absence of micro domains, while the P4bm superlattice spots observed in the SAED pattern of the x = 0.10 ceramic play a key role in its outstanding slim P–E loop and dielectric properties. These results demonstrate that such ceramics (x = 0.10) are expected to be favorable for applications requiring both thermally stable dielectric permittivity and high energy density capability in the electronic industry. © 2025 Elsevier Ltd and Techna Group S.r.l.

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