Unusual set of anomalies in the lattice dynamics of lawsonite near its phase transitions

0569211 - FZÚ 2023 RIV US eng C - Konferenční příspěvek (zahraniční konf.)
Kadlec, Filip - Nuzhnyy, Dmitry - Kadlec, Christelle - Petzelt, Jan - Savinov, Maxim - Kamba, Stanislav
Unusual set of anomalies in the lattice dynamics of lawsonite near its phase transitions.
International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) /47./. New York: IEEE, 2022, č. článku 9895469. ISBN 978-1-7281-9427-1. ISSN 2162-2027.
[International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) /47./. Delft (NL), 28.08.2022-02.09.2022]
Grant CEP: GA ČR(CZ) GA20-01527S
Institucionální podpora: RVO:68378271
Klíčová slova: lawsonite * terahertz spectroscopy * soft mode * dielectric permittivity
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
https://ieeexplore.ieee.org/document/9895469

Lawsonite is a water-containing mineral occurring in the Earth’s crust and mantle, exhibiting low-temperature ferroelectricity linked to water molecules. Using broad-band polarized electromagnetic spectroscopy, we studied the lattice dynamics of a single crystal between 1Hz and 20THz at temperatures from 20 to 500K. We identified three anomalies associated with the two phase transitions occurring at 270 and 124K—a critical GHz relaxation, a soft THz phonon, and an overdamped sub-THz excitation in the E∥a,E∥b and E∥c permittivity spectra, respectively. The fact that the soft mode is polarized perpendicularly to the ferroelectric axis is very unusual.
Trvalý link: https://hdl.handle.net/11104/0340597