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BaZr x Ti 1− x O 3 Epitaxial Thin Films for Electrocaloric Investigations
Author(s) -
Engelhardt Stefan,
Molin Christian,
Gebhardt Sylvia,
Fähler Sebastian,
Nielsch Kornelius,
Hühne Ruben
Publication year - 2018
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201800154
Subject(s) - materials science , ferroelectricity , thin film , pulsed laser deposition , epitaxy , permittivity , analytical chemistry (journal) , dielectric , phase (matter) , condensed matter physics , layer (electronics) , optoelectronics , nanotechnology , chemistry , physics , organic chemistry , chromatography
Epitaxial BaZr x Ti 1− x O 3 (BZT) thin films with a Zr content between x= 0 and x= 0.3 are grown by pulsed laser deposition on (001)‐oriented SrTiO 3 single crystals utilizing a conducting SrRuO 3 buffer layer and Pt top electrodes. An undisturbed epitaxial growth with a smooth and homogeneous surface structure is obtained for all Zr containing films, whereas some preferentially growing grains and twins are observed for pure BaTiO 3 films. Temperature‐dependent measurements of the relative permittivity suggest a diffuse phase transition. The temperature of the maximum permittivity as well as the electrical polarizability at room temperature decrease with increasing Zr content. The observed frequency dependence suggests relaxor ferroelectric properties for all Zr‐containing films. The indirectly determined electrocaloric responses are considerably lower compared to thick films, which is primarily attributed to the diffuse character of the phase transition. A maximum adiabatic temperature change of about 0.3 K for an electric field change of 170 kV cm −1 is found for BaZr 0.2 Ti 0.8 O 3 .