Počet záznamů: 1

The negative phonon confinement effect in nanoscopic sodium nitrite

  1. 1.
    0330274 - FZU-D 2010 RIV GB eng J - Článek v odborném periodiku
    Koroleva, E.Yu. - Nuzhnyy, Dmitry - Pokorný, Jan - Kamba, Stanislav - Kumzerov, Y. A. - Vakhrushev, S. B. - Petzelt, Jan
    The negative phonon confinement effect in nanoscopic sodium nitrite.
    [Negativní vliv rozměrového efektu na fonony v nanoskopickém NaNO2.]
    Nanotechnology. Roč. 20, č. 39 (2009), 395706/1-395706/7 ISSN 0957-4484
    Grant CEP: GA AV ČR KJB100100704; GA ČR(CZ) GA202/09/0682
    Výzkumný záměr: CEZ:AV0Z10100520
    Klíčová slova: nanocomposite * sodium nitrite * infrared * THz * Raman * phonon * effective medium approach
    Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
    Impakt faktor: 3.137, rok: 2009

    A nanocomposite of porous glass and a NaNO2 ferroelectric (channels of 7 nm diameter) was studied using infrared reflectivity, THz transmission and Raman spectroscopy as a function of temperature in the range of 300-500 K, including the ferroelectric transition. From the infrared and THz response the effective dielectric function was calculated and compared with the dielectric functions calculated from the Bruggeman and Lichtenecker models of the effective medium, using the known data on the polar phonon modes of the NaNO2 single crystals. The results show good qualitative agreement, indicating that the stiffening of the effective modes is due to local depolarization fields on the glass-ferroelectric interfaces. The nonpolar Raman modes show no substantial modification compared to those of the bulk NaNO2. Some signatures of the ferroelectric transition were even seen. The results indicate that the intrinsic size effect (phonon confinement) is negligible in this nanocomposite.

    Nanokompozit porézního skla a feroektrického NaNO2 byl studován pomocí infračervené reflexní, THz transmisní a Ramanovské spektroskopie v teplotním oboru 300 - 500 K. Pozorované ztvrdnutí fononových frekvencí je spůsobeno depolarizačním polem na rozhraní skla a feroelektrika. Vliv rozměrového jevu na fonony je zanedbatelný.
    Trvalý link: http://hdl.handle.net/11104/0176103