The structural, dielectric, electrocaloric, and energy storage properties of lead-free Ba0·90Ca0·10Zr0·15Ti0·85O3

Abstract

Lead-free ferroelectric materials with Electrocaloric Effect (ECE) and recoverable energy (W rec ) represent a major breakthrough in the technological race for manufacturing low-cost and eco-friendly smart multifunctional devices. Here, guided by the benefits resulting from successive ferroelectric-ferroelectric (F–F) and ferroelectric-pseudo cubic (F-PC) transitions including broad operational temperature span, lead-free Ba 0·90 Ca 0·10 Zr 0·15 Ti 0·85 O 3 (BCZT) ferroelectric ceramic located near the phase convergence region was prepared using the conventional solid-state solution. In this study, the systematic investigation of structural and microstructural properties via X-Ray Powder Diffraction (XRPD), scanning electron microscopy (SEM), temperature-dependence Raman spectroscopy and dielectric properties confirm the formation of a pure perovskite material which undergoes consecutive R 3 c - R 3 m , R 3 m - Amm 2, Amm 2- P 4 mm (F–F) phase transitions followed by (F-PC) transition in a wide temperature range centered around room temperature (RT). Polarization-Electric field (P-E) measurements, revealed the coexistence of Positive Electro-Caloric Effect (PECE) and Negative Electro-Caloric Effect (NECE) in a wide temperature span of [-40 °C, 95 °C]. More interestingly, we reached a large absolute temperature change (ΔT) and EC coefficient (ξ) values of (5.505 °C, 1.847 KmmkV −1 ), (0.861 °C, 0.289 KmmkV −1 ) and (1.897 °C, 0.637 Kmm kV −1 ) registered respectively at about −5, 42.5 and 74.5 °C under an electric field of 29.80 kVcm −1 . This work will promote further studies on lead-free BCZT ceramics towards multifunctional environmentally-friendly material promising for solid-state cooling technology.