Počet záznamů: 1

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..

  1. 1.
    0347911 - FZU-D 2011 RIV US eng J - Článek v odborném periodiku
    Ferrarelli, M.C. - Nuzhnyy, Dmitry - Sinclair, D.C. - Kamba, Stanislav
    Soft-mode behavior and incipient ferroelectricity in Na1/2Bi1/2Cu3Ti4O12.
    Physical Review. B. Roč. 81, č. 22 (2010), 224112/1-224112/7 ISSN 1098-0121
    Grant CEP: GA ČR(CZ) GA202/09/0682
    Výzkumný záměr: CEZ:AV0Z10100520
    Klíčová slova: infrared and terahertz spectroscopy * soft mode * incipient ferroelectrics
    Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
    Impakt faktor: 3.772, rok: 2010

    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.
    Trvalý link: http://hdl.handle.net/11104/0188576