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Phonon behaviors and dielectric functions in Bi 0.5 Na 0.5 TiO 3 ‐based ceramics by Raman scattering and optical ellipsometry
Author(s) -
Jiao Shan,
Chen Fangfang,
Zhang Yi,
Hu Zhigao,
Duan Zhihua,
Wang Feifei,
Sun Dazhi
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16175
Subject(s) - materials science , phonon , raman spectroscopy , raman scattering , ellipsometry , dielectric , condensed matter physics , permittivity , band gap , ceramic , strontium titanate , scattering , analytical chemistry (journal) , optics , thin film , physics , chemistry , nanotechnology , optoelectronics , composite material , chromatography
The dielectric functions and lattice vibrations of (0.935‐ x )Bi 0.5 Na 0.5 TiO 3 ‐0.065BaTiO 3 ‐ x SrTiO 3 (BNBST x ) ceramics were investigated by temperature‐dependent spectroscopic ellipsometry and Raman scattering. Based on the analysis of dielectric functions with the Tauc‐Lorentz dispersion model, it was found that the band gap and the temperature coefficient increased with the addition of SrTiO 3 . Moreover, the frequency, intensity and/or full width at half maximum of phonon modes related to Bi and Ti‐localized phonon modes exhibited local maximum/minimum around the depolarization temperature and permittivity‐maximum temperature, which indicated the ongoing structural transformation. In addition, the Sr introduction affected the TiO 6 tilting and the off‐center displacement of Ti 4+ . These results seem to be significant for the enhanced response functions with the addition of SrTiO 3 in BNBST x ceramics.