Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films

Strontium titanate-based materials with ferroelectric or relaxor-like properties have drawn vast attention as polar dielectrics for electronics and telecommunications. Here, we study the lattice dynamics in sol–gel-derived Sr1−1.5xBixTiO3</...

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Autores principales:	Alexander Tkach, Olena Okhay, Dmitry Nuzhnyy, Jan Petzelt, Paula M. Vilarinho
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	perovskites polar dielectrics thin films infrared spectroscopy Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85
Acceso en línea:	https://doaj.org/article/b0f9fe9521094241b39438fd0323bac2
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spelling	oai:doaj.org-article:b0f9fe9521094241b39438fd0323bac22021-11-11T17:59:32ZPolar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films10.3390/ma142164141996-1944https://doaj.org/article/b0f9fe9521094241b39438fd0323bac22021-10-01T00:00:00Zhttps://www.mdpi.com/1996-1944/14/21/6414https://doaj.org/toc/1996-1944Strontium titanate-based materials with ferroelectric or relaxor-like properties have drawn vast attention as polar dielectrics for electronics and telecommunications. Here, we study the lattice dynamics in sol–gel-derived Sr<sub>1−1.5x</sub>Bi<sub>x</sub>TiO<sub>3</sub> thin films with x = 0.0053 and 0.167, deposited on Al<sub>2</sub>O<sub>3</sub> substrates, using a variable-temperature far-infrared spectroscopy in a transmittance mode. Bi doping, known to induce a low-frequency dielectric relaxation in SrTiO<sub>3</sub> (ST) ceramics and films, due to off-centre dopant ion displacements generating electric dipoles, is shown to affect the polar phonon behaviour of thin films. We show that in weakly Bi-doped films, the low-frequency polar TO1 mode softens on cooling but less than in undoped ST. In heavily Bi-doped ST films, this mode displays no significant frequency variation with temperature from 300 to 10 K. The polar phonon behaviour of polycrystalline Bi-doped ST thin films is comparable with that of Bi-doped ST ceramics, which exhibit dielectric relaxations and harden soft-mode behaviour instead of the ferroelectric phase transition.Alexander TkachOlena OkhayDmitry NuzhnyyJan PetzeltPaula M. VilarinhoMDPI AGarticleperovskitespolar dielectricsthin filmsinfrared spectroscopyTechnologyTElectrical engineering. Electronics. Nuclear engineeringTK1-9971Engineering (General). Civil engineering (General)TA1-2040MicroscopyQH201-278.5Descriptive and experimental mechanicsQC120-168.85ENMaterials, Vol 14, Iss 6414, p 6414 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	perovskites polar dielectrics thin films infrared spectroscopy Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85
spellingShingle	perovskites polar dielectrics thin films infrared spectroscopy Technology T Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85 Alexander Tkach Olena Okhay Dmitry Nuzhnyy Jan Petzelt Paula M. Vilarinho Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
description	Strontium titanate-based materials with ferroelectric or relaxor-like properties have drawn vast attention as polar dielectrics for electronics and telecommunications. Here, we study the lattice dynamics in sol–gel-derived Sr<sub>1−1.5x</sub>Bi<sub>x</sub>TiO<sub>3</sub> thin films with x = 0.0053 and 0.167, deposited on Al<sub>2</sub>O<sub>3</sub> substrates, using a variable-temperature far-infrared spectroscopy in a transmittance mode. Bi doping, known to induce a low-frequency dielectric relaxation in SrTiO<sub>3</sub> (ST) ceramics and films, due to off-centre dopant ion displacements generating electric dipoles, is shown to affect the polar phonon behaviour of thin films. We show that in weakly Bi-doped films, the low-frequency polar TO1 mode softens on cooling but less than in undoped ST. In heavily Bi-doped ST films, this mode displays no significant frequency variation with temperature from 300 to 10 K. The polar phonon behaviour of polycrystalline Bi-doped ST thin films is comparable with that of Bi-doped ST ceramics, which exhibit dielectric relaxations and harden soft-mode behaviour instead of the ferroelectric phase transition.
format	article
author	Alexander Tkach Olena Okhay Dmitry Nuzhnyy Jan Petzelt Paula M. Vilarinho
author_facet	Alexander Tkach Olena Okhay Dmitry Nuzhnyy Jan Petzelt Paula M. Vilarinho
author_sort	Alexander Tkach
title	Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
title_short	Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
title_full	Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
title_fullStr	Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
title_full_unstemmed	Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films
title_sort	polar phonon behaviour in polycrystalline bi-doped strontium titanate thin films
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/b0f9fe9521094241b39438fd0323bac2
work_keys_str_mv	AT alexandertkach polarphononbehaviourinpolycrystallinebidopedstrontiumtitanatethinfilms AT olenaokhay polarphononbehaviourinpolycrystallinebidopedstrontiumtitanatethinfilms AT dmitrynuzhnyy polarphononbehaviourinpolycrystallinebidopedstrontiumtitanatethinfilms AT janpetzelt polarphononbehaviourinpolycrystallinebidopedstrontiumtitanatethinfilms AT paulamvilarinho polarphononbehaviourinpolycrystallinebidopedstrontiumtitanatethinfilms
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Polar Phonon Behaviour in Polycrystalline Bi-Doped Strontium Titanate Thin Films

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