Enhanced electrical properties and large electrocaloric effect in lead-free Ba0.8Ca0.2ZrxTi1−xO3 (x = 0 and 0.02) ceramics - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Materials Science: Materials in Electronics Année : 2020

Enhanced electrical properties and large electrocaloric effect in lead-free Ba0.8Ca0.2ZrxTi1−xO3 (x = 0 and 0.02) ceramics

Résumé

The effects of 2% Zr introduction in Ba0.8Ca0.2TiO3 (BCT) system on its electrical and electrocaloric properties was investigated. BCT and Ba0.8Ca0.2Zr0.02Ti0.98O3 (BCZT) ceramics synthesized by solid-state processing were crystallized in a pure perovskite phase with a group space P4mm. After Zr insertion, the enhanced dielectric constant was obtained around the Curie temperature (Tc) in BCZT ceramic (εr = 6330 at Tc = 388 K) compared to BCT ceramic (εr = 5080 at Tc = 388.6 K). Moreover, the large-signal piezoelectric coefficient (d∗33) was improved from 270 to 310 pm/V in BCT and BCZT ceramics, respectively, under a moderate electric field of 25 kV/cm. The electrocaloric effect was determined via indirect and direct methods. In the indirect approach, the electrocaloric temperature change (ΔT) was calculated via Maxwell relation, and the measured ferroelectric polarization P (E, T) extracted from the P–E curves recorded at 24 kV/cm. The maximum values of ΔT = 0.68 K and the electrocaloric responsivity ζ = 0.283 K mm/kV obtained at 385 K in BCZT ceramic were found to be higher than those observed in BCT ceramic (ΔT = 0.37 K and ζ = 0.154 K mm/kV at 387 K). In the direct approach, ΔT was measured utilizing a modified high-resolution calorimeter at 14 kV/cm. As the direct method is more sensitive to the latent heat, it provided larger values for smaller applied field, i.e., ΔT = 0.474 and 0.668 K for BCT and BCZT ceramics, respectively. A significant ζ of 0.477 K mm/kV was obtained in BCZT at 385 K and 14 kV/cm that matches the values found in lead-based materials. These results suggest that BCZT lead-free ceramics could have an excellent potential to be used in solid-state refrigeration applications.

Domaines

Matériaux

Dates et versions

hal-02987073 , version 1 (03-11-2020)

Identifiants

Citer

Soukaina Merselmiz, Zouhair Hanani, Said Ben Moumen, Aleksander Matavž, Daoud Mezzane, et al.. Enhanced electrical properties and large electrocaloric effect in lead-free Ba0.8Ca0.2ZrxTi1−xO3 (x = 0 and 0.02) ceramics. Journal of Materials Science: Materials in Electronics, 2020, 31 (19), pp.17018-17028. ⟨10.1007/s10854-020-04259-w⟩. ⟨hal-02987073⟩
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