Number of the records: 1  

Perovskites and other framework structure crystalline materials: new trends and perspectives

  1. 1.
    0553887 - FZÚ 2022 RIV FR eng M - Monography Chapter
    Buixaderas, Elena - Dec, J.
    Phonons and relaxations in unfilled tetragonal tungsten-bronzes.
    Perovskites and other framework structure crystalline materials: new trends and perspectives. Frontignan: Collaborating Academics, 2021 - (Saint-Gregoire, P.; Smirnov, M.), s. 281-306. ISBN 979-8583096497
    R&D Projects: GA ČR GA16-09142S
    Institutional support: RVO:68378271
    Keywords : phonons * relaxations * IR spectroscopy * Raman spectroscopy * dielectric response * TTBs
    OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
    http://perovskitesandotherfws.co-ac.com

    The lead-free unfilled tetragonal tungsten-bronzes SBN and CBN had been studied by Raman, infrared and high-frequency dielectric spectroscopies to understand the origin of the phase transition. The substitution in the different channels affects phonon parameters as well as relaxations. Identification of the external modes was done by aid of site group analysis of the structure and respective Raman and IR spectra. It is shown that CBN can show also a small Ca occupancy in the pentagonal channels. Relaxations in SBN show similar qualitative behaviour on increasing Sr content and relaxor behaviour, but for the extreme relaxor samples all frequencies are higher, and the contribution to the permittivity of excitations at GHz-THz range is much stronger. The presence of a soft anharmonic central mode at THz range, and the slowing down of a relaxation at GHz-MHz ranges reveals the coexistence of displacive and order-disorder mechanisms of the phase transition in these materials.
    Permanent Link: http://hdl.handle.net/11104/0328583

     
     
Number of the records: 1  

  This site uses cookies to make them easier to browse. Learn more about how we use cookies.