Elctrocaloric measurements in lead-free materials

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ABSTRACT:

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B. Asbani1,2, J.-L. Dellis1, A. Lahmar1, Y. Gagou1, M. Amjoud2, M. Trček3, Z. Kutnjak3, D. Mezzane2 and M. El Marssi1,a)

1 LPMC, Université de Picardie Jules Verne, 33 rue Saint-Leu, 80039 Amiens Cédex, France

2 LMCN, F.S.T.G. Université Cadi Ayyad,  BP 549, Marrakech, Morocco

3 Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia

 

The electrocaloric (ECE) effect was investigated in lead-free doped Ba0.8Ca0.2TiO3 ceramics synthesized by a conventional sintering process.  All analyzed ceramics exhibit  tetragonal structure. The dielectric spectroscopy and calorimetry revealed that the Curie temperature decreases as a consequence of elements doping and that the ceramics exhibits a first order ferroelectric phase transition. Direct measurements using high resolution calorimetry were compared to the two indirect measurements using the Maxwell relationship. In a first well-known indirect method, P-E hysteresis loops were measured in a wide temperature range and pyroelectric coefficient and thus the electrocaloric responsivity were determined by derivation of P(T, E) data. In second method the electrocaloric responsivity was determined by direct measurements of the pyroelectric coefficient  and consequently the electrocaloric responsivity ξ was determined by direct measurements of the pyroelectric currents under different applied electric fields [1]. Good agreement was obtained between different methods and large electrocaloric responsivity was found for some critical compositions around the dielectric maximum [2,3,4].

 

a) mimoun.elmarssi@u-picardie.fr

 

[1] B. Asbani, J-L. Dellis, Y. Gagou, H. Kaddoussi,  A. Lahmar, M. Amjoud, D. Mezzane, Z. Kutnjak, M. El Marssi

EPL (Europhysics Letters) 111, 57008 (2015)

[2] B. Asbani, J.-L. Dellis, A. Lahmar, M. Courty, M. Amjoud, Y. Gagou, K. Djellab, D. Mezzane, Z. Kutnjak, M. El Marssi

Applied Physics Letters 106, 042902 (2015)

[3] H. Kaddoussi, A. Lahmar, Y. Gagou, B. Asbani, J.-L. Dellis, G. Cordoyiannis, B. Allouche, H. Khemakhem, Z. Kutnjak, M. El Marssi

Journal of Alloys and Compounds, 667, 198 (2016)

[4] B Asbani, Y Gagou, J-L Dellis, A Lahmar, M Amjoud, D Mezzane, Z Kutnjak,

Solid State Communications, 237–238, P 49–54 (2016)

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BIOGRAPHIE:

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Mimoun El Marssi is Professor at Université of Picardy, Amiens in France. He is the head of the laboratory of Physics of Condensed Matter (LPMC). He conducts research on the synthesis and characterization of ferroïc materials with controlled structures and functionalities for electronic and energy. A large part of his research concerns the use of Raman spectroscopy to study the symmetries, stresses and phase transitions in ferroic materials in bulk, epitaxial thin films and superlattices. Recently, he interested to study the lead-free electrocaloric materials. He has co-authored more than 100 scientific publications.

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