Energy storage and electrocaloric properties of lead free (1‐x)(0.6Ba(Zr_0.2Ti_0.8)O₃‐0.4(Ba_0.7Ca_0.3)TiO₃)–xBiZn_0.5Ti_0.5O₃ ferroelectric ceramics

Abstract

In the present work, we investigated the effect of BiZn_0.5Ti_0.5O₃ composition on energy storage and electrocaloric properties of lead free (1-x)(0.6Ba(Zr_0.2Ti_0.8)O₃‐0.4(Ba_0.7Ca_0.3)TiO₃)–xBiZn_0.5Ti_0.5O₃ [BZCT-BZ] ceramics by varying the x from 0 to 10%. The x-ray diffraction (XRD) analysis evidences the formation of BZCT-BZ solid solution without any secondary or impurity phase. The peaks splitting at 2θ = $\sim$ 45^° and 66^° suggested the co-existence of rhombohedral (R) and tetragonal (T) phases (morphotropic phase boundary) at room temperature for x ≤ 1%. Further, BZCT-BZ ceramics with x $>$1% exhibited pseudocubic nature. The ferroelectric hysteresis loop confirms relaxor behavior and the decrease in remanent polarization with increase of BZ content is explained based on the back switching calculations. The BZCT-BZ ceramics as function of BZ composition gave the optimum recoverable energy density of 197 mJ/cm³ and an efficiency of 92% at an applied field of 45 kVcm⁻¹. Such an exceptionally high energy storage efficiency is attributed to the enhanced relaxor behavior and superior back switching capability. Further, the values of electrocaloric temperature change and responsivity are found to be 0.67 K at 45 kV/cm and 0.014 Kcm/kV respectively in 0.98BZCT-0.02BZ ceramics. Thus, BZCT-BZ ceramics are appealing candidates for energy storage and electrocaloric application.

Keywords:

• Pb-free ceramics
• Energy storage capacitors
• Relaxor ferroelectrics
• Back switching
• Electrocaloric effect

Disclosure statement

No potential conflict of interest was reported by the authors.