Phase transitions in the (NH4)2NbOF5 oxyfluoride

The thermal and dielectric properties of the (NH 4 ) 2 NbOF 5 oxyfluoride have been investigated. It has been established that the structural phase transitions Cmc 2 1 → C 2 → Ia observed at the temperatures T 1 = 258.0 K and T 2 = 218.9 K exhibit a nonferroelectric nature. The hydrostatic pressure,...

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Bibliographic Details
Published in:Physics of the solid state 2010, Vol.52 (4), p.781-788
Main Authors: Fokina, V. D., Bogdanov, E. V., Gorev, M. V., Molokeev, M. S., Pogorel’tsev, E. I., Flerov, I. N., Laptash, N. M.
Format: Article
Language:English
Subjects:
Lattice Dynamics and Phase Transitions
Physics
Physics and Astronomy
Solid State Physics
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Summary:The thermal and dielectric properties of the (NH 4 ) 2 NbOF 5 oxyfluoride have been investigated. It has been established that the structural phase transitions Cmc 2 1 → C 2 → Ia observed at the temperatures T 1 = 258.0 K and T 2 = 218.9 K exhibit a nonferroelectric nature. The hydrostatic pressure, which stabilizes the initial phase and destabilizes the low-temperature phase, hardly affects the temperature range of stability of the intermediate phase. The model of sequential ordering of the structural elements due to phase transitions has been analyzed using experimental data on the entropies of the phase transitions.
ISSN:1063-7834
1090-6460
DOI:10.1134/S1063783410040189