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Soft-mode behavior and incipient ferroelectricity in Na.sub.1/2./sub.Bi.sub.1/2./sub.Cu.sub.3./sub.Ti.sub.4./sub.O.sub.12./sub..
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SYSNO ASEP 0347911 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Soft-mode behavior and incipient ferroelectricity in Na1/2Bi1/2Cu3Ti4O12. Author(s) Ferrarelli, M.C. (GB)
Nuzhnyy, Dmitry (FZU-D) RID, ORCID
Sinclair, D.C. (GB)
Kamba, Stanislav (FZU-D) RID, ORCID, SAISource Title Physical Review. B - ISSN 1098-0121
Roč. 81, č. 22 (2010), 224112/1-224112/7Number of pages 6 s. Language eng - English Country US - United States Keywords infrared and terahertz spectroscopy ; soft mode ; incipient ferroelectrics Subject RIV BM - Solid Matter Physics ; Magnetism R&D Projects GA202/09/0682 GA ČR - Czech Science Foundation (CSF) CEZ AV0Z10100520 - FZU-D (2005-2011) UT WOS 000279090100001 DOI 10.1103/PhysRevB.81.224112 Annotation Na1/2Bi1/2Cu3Ti4O12.(NBCTO) ceramics exhibit high intrinsic relative permittivity of ~145 at 300 K that rises on cooling and levels off below ~50 K with a value of ~260 at 10 K without any signature of a structural transition. Such behavior is a typical feature of incipient ferroelectrics such as the perovskite CaTiO3. Infrared and terahertz spectroscopy on NBCTO ceramics are presented and reveal a room-temperature soft polar optic mode at ~34 cm-1 that softens on cooling and is responsible for the temperature dependence of the relative permittivity. The temperature dependence of the soft-mode frequency obeys the Barrett formula with the onset of quantum fluctuations T1 occurring near 85 K and a hypothetical Curie temperature T0 of ~−155 K. A fitted vibrational zero-point energy (kBT1)/2 is in good agreement with the measured soft-mode frequency. Workplace Institute of Physics Contact Kristina Potocká, potocka@fzu.cz, Tel.: 220 318 579 Year of Publishing 2011
Number of the records: 1