A novel relaxor (Bi,Na,Ba)(Ti,Zr)O₃ lead‐free ceramic with high energy storage performance

Abstract

Energy storage ceramic capacitors advance in high power density and working voltage, but challenge in simultaneously large recoverable energy density (W rec ), high energy efficiency (η), and good thermal stability. To achieve this, a novel lead-free ceramic system (1x)(Bi 0.5 Na 0.5 )TiO 3x(BaZr 0.3 Ti 0.7 O 3 ) [( 1x)BNT-xBZT] was explored by tailoring the ferroelectric relaxor states. The introduction of BZT gradually promotes the transformation of ferroelectric states into relaxor states at around the room temperature for x = 0.3-0.5 that presents a pinched P-E loop. The optimized composition of x = 0.45 possesses a large W rec of up to 2.6 J/cm 3 and ultrahigh ƞ of 94%, with only a small variation (±8%) in W rec and the high ƞ (90%) over a broad temperature range (−30°C to 180°C), demonstrating the superior performances compared to many existing lead-free ceramics. The remarkable advantages of the novel BNT-BZT lead-free ceramics explored in this study are thus promising for the highefficiency and temperature-stable energy storage capacitor applications.

Ultrahigh Polarization Response along Large Energy Storage Properties in BiFeO3–BaTiO3-Based Relaxor Ferroelectric Ceramics under Low Electric Field

“…A comparative analysis of W rec and η values between our optimized ceramics and currently declared dielectric ceramics are exhibited in Figure i. Note that the high W rec reported was usually achieved under a high E b (>300 kV/cm), while it is rare to acquire a terrific W rec (>3.5 J/cm 3 ) under a low E b (<200 kV/cm). ,,− ,− ,,,,− Practically, the electrostatic energy storage devices working at high electric field for a long time may cause security risks, which is a great challenge for the insulation of materials. In addition, to intuitively estimate the best ESP, the energy storage coefficient Q ( Q = W rec / E ) has been used, and the result is summarized in Figure j.…”

Energy storage performance of BiFeO3–SrTiO3–BaTiO3 relaxor ferroelectric ceramics

“…1 Hence, the large or small ε r will lead to electromechanical breakdown for dielectric ceramics under high electric fields. [1][2][3][4] In order to describe the relaxor behavior of (0.55−x)BFO-0.45STO-xBTO ceramics quantitatively, the modified Curie-Weiss law is employed based on following equation: [20][21][22]…”

“…Generally, γ = 1 represents a normal ferroelectric material, while γ = 2 indicates ideal relaxor ferroelectrics. [20][21][22] The fitting results are presented in Figure 4a, and the composition-dependent γ is plotted in Figure 4b. The linear relationship between ln(1/ε−1/ε r ) and ln(T-T m ) suggests the reliability of fitting results, and the γ increases from 1.68 for x = 0 to the value larger than 1.9 for x > 0.05, which further confirms the enhancement of relaxor properties.…”

“…In order to describe the relaxor behavior of (0.55− x )BFO–0.45STO– x BTO ceramics quantitatively, the modified Curie‐Weiss law is employed based on following equation: 20–22 $$\begin{equation}\frac{1}{{{\varepsilon _r}}} - \;\frac{1}{{{\varepsilon _{r,max}}}} = \frac{{{{\left( {T - {T_m}} \right)}^\gamma }}}{C}\;(T &gt; {T_m})\end{equation}$$where γ is the diffusion degree, C is the Curie‐Weiss constant. Generally, γ = 1 represents a normal ferroelectric material, while γ = 2 indicates ideal relaxor ferroelectrics 20–22 . The fitting results are presented in Figure 4a, and the composition‐dependent γ is plotted in Figure 4b.…”

High energy storage density achieved in BNT‐based ferroelectric translucent ceramics under low electric fields

“…The introduction of BaZr 0.3 Ti 0.7 O 3 (BZT) into BNT to form a solid solution allows for the proportion of phase structures to be tuned and broadens the optical band gap. 23 The difference in ionic radii between Zr 4+ and Ti 4+ contributes to hindering the long-range ordering of ferroelectric domains, inducing PNRs. 24,25 The addition of Ba 2+ ions can enhance the polarization field and stabilize the polarization by increasing the long-range correlated ferroelectric P4mm phase.…”