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Role of trivalent Sr substituents and Sr vacancies in tetragonaland polar states of SrTiO.sub.3./sub..
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SYSNO ASEP 0366112 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Role of trivalent Sr substituents and Sr vacancies in tetragonaland polar states of SrTiO3. Tvůrce(i) 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, SAIZdroj.dok. Acta Materialia. - : Elsevier - ISSN 1359-6454
Roč. 59, č. 14 (2011), 5388-5397Poč.str. 10 s. Jazyk dok. eng - angličtina Země vyd. GB - Velká Británie Klíč. slova phase transformations ; dynamic phenomena ; Raman spectroscopy ; lattice defect vacancies ; perovskites Vědní obor RIV BM - Fyzika pevných látek a magnetismus CEP KAN301370701 GA AV ČR - Akademie věd CEZ AV0Z10100520 - FZU-D (2005-2011) UT WOS 000294091400002 DOI 10.1016/j.actamat.2011.05.011 Anotace 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. Pracoviště Fyzikální ústav Kontakt Kristina Potocká, potocka@fzu.cz, Tel.: 220 318 579 Rok sběru 2012
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