Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films

Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films

Substantial efforts are dedicated worldwide to use lead-free materials for environmentally friendly processes in electrocaloric cooling. Whereas investigations on bulk materials showed that Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub> (NBT)-based compounds migh...

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Main Authors: Bruno Magalhaes, Stefan Engelhardt, Christian Molin, Sylvia E. Gebhardt, Kornelius Nielsch, Ruben Hühne
Format: Article
Language:English
Published: MDPI AG 2021-05-01
Series:Coatings
Subjects:
ferroelectrics
epitaxy
thin films
pulsed laser deposition
Online Access:https://www.mdpi.com/2079-6412/11/6/651
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spelling doaj-562432866229449291be3b5bb002a2ab2021-06-01T01:31:33ZengMDPI AGCoatings2079-64122021-05-011165165110.3390/coatings11060651Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin FilmsBruno Magalhaes0Stefan Engelhardt1Christian Molin2Sylvia E. Gebhardt3Kornelius Nielsch4Ruben Hühne5Leibniz-IFW Dresden, Institute for Metallic Materials, 01069 Dresden, GermanyLeibniz-IFW Dresden, Institute for Metallic Materials, 01069 Dresden, GermanyFraunhofer IKTS, Fraunhofer Institute for Ceramic Technologies and Systems, Winterbergstraße 28, 01277 Dresden, GermanyFraunhofer IKTS, Fraunhofer Institute for Ceramic Technologies and Systems, Winterbergstraße 28, 01277 Dresden, GermanyLeibniz-IFW Dresden, Institute for Metallic Materials, 01069 Dresden, GermanyLeibniz-IFW Dresden, Institute for Metallic Materials, 01069 Dresden, GermanySubstantial efforts are dedicated worldwide to use lead-free materials for environmentally friendly processes in electrocaloric cooling. Whereas investigations on bulk materials showed that Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub> (NBT)-based compounds might be suitable for such applications, our aim is to clarify the feasibility of epitaxial NBT-based thin films for more detailed investigations on the correlation between the composition, microstructure, and functional properties. Therefore, NBT-based thin films were grown by pulsed laser deposition on different single crystalline substrates using a thin epitaxial La<sub>0.5</sub>Sr<sub>0.5</sub>CoO<sub>3</sub> layer as the bottom electrode for subsequent electric measurements. Structural characterization revealed an undisturbed epitaxial growth of NBT on lattice-matching substrates with a columnar microstructure, but high roughness and increasing grain size with larger film thickness. Dielectric measurements indicate a shift of the phase transition to lower temperatures compared to bulk samples as well as a reduced permittivity and increased losses at higher temperatures. Whereas polarization loops taken at −100 °C revealed a distinct ferroelectric behavior, room temperature data showed a significant resistive contribution in these measurements. Leakage current studies confirmed a non-negligible conductivity between the electrodes, thus preventing an indirect characterization of the electrocaloric properties of these films.https://www.mdpi.com/2079-6412/11/6/651ferroelectricsepitaxythin filmspulsed laser deposition
collection DOAJ
language English
format Article
sources DOAJ
author Bruno Magalhaes
Stefan Engelhardt
Christian Molin
Sylvia E. Gebhardt
Kornelius Nielsch
Ruben Hühne
spellingShingle Bruno Magalhaes
Stefan Engelhardt
Christian Molin
Sylvia E. Gebhardt
Kornelius Nielsch
Ruben Hühne
Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
Coatings
ferroelectrics
epitaxy
thin films
pulsed laser deposition
author_facet Bruno Magalhaes
Stefan Engelhardt
Christian Molin
Sylvia E. Gebhardt
Kornelius Nielsch
Ruben Hühne
author_sort Bruno Magalhaes
title Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
title_short Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
title_full Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
title_fullStr Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
title_full_unstemmed Structural and Electric Properties of Epitaxial Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>-Based Thin Films
title_sort structural and electric properties of epitaxial na<sub>0.5</sub>bi<sub>0.5</sub>tio<sub>3</sub>-based thin films
publisher MDPI AG
series Coatings
issn 2079-6412
publishDate 2021-05-01
description Substantial efforts are dedicated worldwide to use lead-free materials for environmentally friendly processes in electrocaloric cooling. Whereas investigations on bulk materials showed that Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub> (NBT)-based compounds might be suitable for such applications, our aim is to clarify the feasibility of epitaxial NBT-based thin films for more detailed investigations on the correlation between the composition, microstructure, and functional properties. Therefore, NBT-based thin films were grown by pulsed laser deposition on different single crystalline substrates using a thin epitaxial La<sub>0.5</sub>Sr<sub>0.5</sub>CoO<sub>3</sub> layer as the bottom electrode for subsequent electric measurements. Structural characterization revealed an undisturbed epitaxial growth of NBT on lattice-matching substrates with a columnar microstructure, but high roughness and increasing grain size with larger film thickness. Dielectric measurements indicate a shift of the phase transition to lower temperatures compared to bulk samples as well as a reduced permittivity and increased losses at higher temperatures. Whereas polarization loops taken at −100 °C revealed a distinct ferroelectric behavior, room temperature data showed a significant resistive contribution in these measurements. Leakage current studies confirmed a non-negligible conductivity between the electrodes, thus preventing an indirect characterization of the electrocaloric properties of these films.
topic ferroelectrics
epitaxy
thin films
pulsed laser deposition
url https://www.mdpi.com/2079-6412/11/6/651
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