Electrocaloric effect in Ba0.2Ca0.8Ti0.95Ge0.05O3 determined by a new pyroelectric method

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

doi:10.1209/0295-5075/111/57008

All issues

Volume 111 / No 5 (September 2015)

EPL, 111 5 (2015) 57008

Abstract

Issue		EPL Volume 111, Number 5, September 2015


Article Number		57008
Number of page(s)		5
Section		Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI		https://doi.org/10.1209/0295-5075/111/57008
Published online		29 September 2015

EPL, 111 (2015) 57008

Electrocaloric effect in Ba_0.2Ca_0.8Ti_0.95Ge_0.05O₃ determined by a new pyroelectric method

B. Asbani¹, J.-L. Dellis¹, Y. Gagou¹, H. Kaddoussi¹, A. Lahmar¹, M. Amjoud², D. Mezzane², Z. Kutnjak³ and M. El Marssi¹^(a)

¹ Laboratoire de Physique de la Matière Condensée, Université de Picardie - 33 rue Saint-Leu, 80039 Amiens Cedex, France
² LMCN, F.S.T.G. Université Cadi Ayyad - BP 549, Marrakech, Morocco
³ Jozef Stefan Institute - Jamova cesta 39, 1000 Ljubljana, Slovenia

^(a) mimoun.elmarssi@u-picardie.fr

Received: 24 July 2015
Accepted: 4 September 2015

Abstract

The present letter explores the electrocaloric effect (ECE) in the lead-free oxide Ba_0.8Ca_0.2Ti_0.95Ge_0.05O₃ ceramics (BCTG). The electrocaloric responsivity $\xi =(\frac{\text{d}T}{\text{d}E})$ was determined by two different methods using the Maxwell relationship $\xi\propto\left(\frac{\partial P}{\partial T}\right)_{E}$ . In a first well-known indirect method, $P\text{-}E$ hysteresis loops were measured in a wide temperature range from which the pyroelectric coefficient $p_{E}=\left(\frac{\partial P}{\partial T}\right)_{E}$ and thus ξ were determined by derivation of $P(T,~E)$ data. In the second novel method the pyroelectric coefficient p_E and consequently the electrocaloric responsivity ξ were determined by direct measurements of the pyroelectric currents under different applied electric fields. Within the experimental error, good agreement was obtained between two methods with $\xi = 0.18 \pm 0.05 \cdot 10^{-6}\ \text{K}\cdot \text{m}\cdot \text{V}^{-1}$ at about 410 K.

PACS: 77.70.+a – Pyroelectric and electrocaloric effects / 77.84.-s – Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials / 77.80.B- – Phase transitions and Curie point

© EPLA, 2015

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