Role of trivalent Sr substituents and Sr vacancies in tetragonaland polar states of SrTiO.sub.3./sub..

Tkach, A.; Correia, T.M.; Almeida, A.; Moreira, J.A.; Chaves, M. R.; Okhay, O.; Vilarinho, P. M.; Gregora, Ivan; Petzelt, Jan

doi:https://dx.doi.org/10.1016/j.actamat.2011.05.011

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Role of trivalent Sr substituents and Sr vacancies in tetragonaland polar states of SrTiO.sub.3./sub..

1.

SYSNO ASEP	0366112
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Role of trivalent Sr substituents and Sr vacancies in tetragonaland polar states of SrTiO₃.
Author(s)	Tkach, A. (PT) Correia, T.M. (PT) Almeida, A. (PT) Moreira, J.A. (PT) Chaves, M. R. (PT) Okhay, O. (PT) Vilarinho, P. M. (PT) Gregora, Ivan (FZU-D)_{RID, ORCID} Petzelt, Jan (FZU-D)_{RID, ORCID, SAI}
Source Title	Acta Materialia. - : Elsevier - ISSN 1359-6454 Roč. 59, č. 14 (2011), 5388-5397
Number of pages	10 s.
Language	eng - English
Country	GB - United Kingdom
Keywords	phase transformations ; dynamic phenomena ; Raman spectroscopy ; lattice defect vacancies ; perovskites
Subject RIV	BM - Solid Matter Physics ; Magnetism
R&D Projects	KAN301370701 GA AV ČR - Academy of Sciences of the Czech Republic (AV ČR)
CEZ	AV0Z10100520 - FZU-D (2005-2011)
UT WOS	000294091400002
DOI	10.1016/j.actamat.2011.05.011
Annotation	Raman scattering is used to study strontium titanate (STO) ceramics with several heterovalent dopants(La3+, Gd3+, Y3+), which substitute Sr2+ ions. Extraordinary shift of the antiferrodistortive transition temperature (Ta) is observed when a small percentage these dopants is used. A common linear dependence of Ta vs. tolerance factor t is obtained if strontium vacancies are taken into account. A vacancy size of ~1.547 A˚ was estimated, ~7% larger than the Sr2+ radius. This vacancy size can directly explain the increase in lattice parameter with increasing Bi3+ content in Bi-doped STO. The introduction of La3+, Gd3+ or Y3+ ions at the Sr site causes a considerable stiffening of the transverse optic TO1 mode at low temperatures, thereby decreasing the phonon contribution to the dielectric permittivity. No traces of a ferroelectric phase are found for any of the dopants used.
Workplace	Institute of Physics
Contact	Kristina Potocká, potocka@fzu.cz, Tel.: 220 318 579
Year of Publishing	2012

Number of the records: 1