Dielectric permittivity enhancement and large electrocaloric effect in the lead free (Ba0.8Ca0.2)(1-x)La2x/3TiO3 ferroelectric ceramics

B. Asbani (1) , Y. Gagou (2) , M. Trcek , J. -L. Dellis , M. Amjoud (3) , A. Lahmar (2) , D. Mezzane (3) , Z. Kutnjak (4) , M. El Marssi (2)

1 IMN - Institut des Matériaux Jean Rouxel
2 LPMC - Laboratoire de Physique de la Matière Condensée - UR UPJV 2081
3 LMCN - Laboratoire de Matière Condensée et Nanostructures
4 IJS - Jozef Stefan Institute [Ljubljana]

Lanthanum (La) incorporation in the (Ba(0.8)Ca(0.)2)TiO3 (BCT) matrix induces enhancement of electrocaloric effect, decrease of Curie temperature and increase of dielectric permittivity. We studied the influence of La substitution ceramics on grain size and electrocaloric effect (ECE) in BCT matrix using both indirect and direct methods. From ferroelectric polarization and pyroelectric measurements, we calculate ECE response versus temperature for all the (Ba0.8Ca0.2)(1-x)La2x/3TiO3 (xBCTL) ceramics compositions ranging from x = 0 to 0.05. The results showed good agreement between the two methods at the same applied electric field. A maximal value of electrocaloric (EC) temperature change Delta T = 0.30 K was obtained at 25 kV/cm corresponding to an EC responsivity xi = 0.120 x 10(-6) K m/V, in a wide temperature region in the vicinity of the ferroelectric phase transition temperature (250 K-400 K) for x = 0.05 that places this family as very promising materials for electrocaloric applications near room temperature. (C) 2017 Elsevier B.V. All rights reserved.

Domaines: Matière Condensée [cond-mat]

B. Asbani, Y. Gagou, M. Trcek, J. -L. Dellis, M. Amjoud, et al.. Dielectric permittivity enhancement and large electrocaloric effect in the lead free (Ba0.8Ca0.2)(1-x)La2x/3TiO3 ferroelectric ceramics. Journal of Alloys and Compounds, 2018, 730, pp.501-508. ⟨10.1016/j.jallcom.2017.09.301⟩. ⟨hal-03627575⟩