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Electrocaloric Effect in Ba(Zr,Ti)O 3 –(Ba,Ca)TiO 3 Ceramics Measured Directly
Author(s) -
Sanlialp Mehmet,
Shvartsman Vladimir V.,
Acosta Matias,
Lupascu Doru C.
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14456
Subject(s) - curie temperature , materials science , electrocaloric effect , tetragonal crystal system , ferroelectricity , ferroelectric ceramics , ceramic , analytical chemistry (journal) , atmospheric temperature range , condensed matter physics , phase transition , electric field , solid solution , calorimeter (particle physics) , mineralogy , phase (matter) , thermodynamics , dielectric , chemistry , physics , metallurgy , optics , ferromagnetism , optoelectronics , organic chemistry , chromatography , quantum mechanics , detector
In this paper, we report on studies of the electrocaloric ( EC ) effect in lead‐free (1− x )Ba(Zr 0.2 Ti 0.8 )O 3 – x (Ba 0.7 Ca 0.3 )TiO 3 ceramics with compositions range between 0.32 ≤ x ≤ 0.45. The EC effect was measured directly using a modified differential scanning calorimeter. The maximum EC temperature change, ΔT direct = 0.33 K under an electric field of 2 kV/mm, was observed for the composition with x = 0.32 at ~63°C. We found that the EC effect peaks not only around the Curie temperature but also at the transition between the ferroelectric phases with different symmetries. A strong discrepancy observed between the results of the direct measurements and indirect estimations points out that using Maxwell's equations is invalid for the thermodynamic nonequilibrium conditions that accompany only partial (incomplete) poling of ceramics. We also observe a nonlinearity of the EC effect above the Curie temperature and in the temperature range corresponding to the tetragonal ferroelectric phase.