Structural investigation, dielectric, ferroelectric, and elecrocaloric properties of lead-free Ba(1−x)CaxTi(1−x)(Li1/3Nb2/3)xO3−δ (x = 0.02 and x = 0.07) ceramics
Résumé
The ferroelectric lead-free Ba(1−x)CaxTi(1−x)(Li1/3Nb2/3)xO3−δ with x = 0.02 and x = 0.07 (BCLNTO2 and BCLNTO7) ceramics were elaborated by a conventional sintering process. The effects of Ca and (Li, Nb) contents in the BTO matrix on the structure, dielectric, ferroelectric and electrocaloric properties were investigated. The refinement of the structure at room temperature showed that both BCLNTO2 and BCLNTO7 ceramics crystallize in the tetragonal system. Ferroelectric and dielectric investigations revealed the presence of three phase transitions similar to the parent phase BTO. Applying the Maxwell relation, the electrocaloric temperature changes were calculated using P–E hysteresis loops adjusted at different temperatures. The electrocaloric responsivity was found ξmax (ΔT/ΔE) = 0.14 K mm/kV at TECmax = 374 and ξmax = 0.12 K mm/kV at TECmax= 302 K for BCLNTO2 and BCLNTO7, respectively.