Infrared, Raman and high-frequency dielectric spectroscopy and the phase transitions in Na1/2Bi1/2TiO3

Autor:	V. Porokhonskyy, I. Franke, J Fábry, D. Noujni, Jan Suchanicz, R. S. Klein, Jan Petzelt, G E Kugel, Alexej Pashkin, Stanislav Kamba, Krystian Roleder
Rok vydání:	2004
Předmět:	Permittivity Condensed matter physics Chemistry Infrared Physics::Optics Infrared spectroscopy Dielectric Condensed Matter Physics Dielectric spectroscopy Condensed Matter::Materials Science symbols.namesake symbols General Materials Science Dielectric loss Raman spectroscopy Spectroscopy
Zdroj:	Journal of Physics: Condensed Matter. 16:2719-2731
ISSN:	1361-648X 0953-8984
Popis:	Infrared reflectivity, time-domain terahertz transmission, high-frequency dielectric measurements and Raman spectroscopy of Na0.5Bi0.5TiO3 complex ferroelectric perovskite were performed in a broad temperature range. The results were analysed considering the macroscopic symmetry as well as symmetry resulting from local Na–Bi ordering in all three known phases. An overdamped infrared soft mode was revealed in the THz range which, together with central-mode type dispersion in the GHz range, contribute to the strong and broad dielectric permittivity maximum around 600 K. Anharmonic Bi and/or Na vibrations and local hopping, respectively, are suggested to be the main origins of these excitations. The broad phonon spectra and the frequency independent dielectric losses at low temperatures are compatible with the existence of nanoscopic polar regions and disorder to liquid He temperatures similar to relaxor ferroelectrics.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6147c940015db0b144d4b1b61b7bfec7 https://doi.org/10.1088/0953-8984/16/15/022 Zobrazit plný text záznamu