Инд. авторы:	Krylov A., Laptash N., Vtyurin A., Krylova S.
Заглавие:	Phase transitions in (NH4)(2)MoO2F4 crystal
Библ. ссылка:	Krylov A., Laptash N., Vtyurin A., Krylova S. Phase transitions in (NH4)(2)MoO2F4 crystal // JOURNAL OF MOLECULAR STRUCTURE. - 2016. - Vol.1124. - P.125-130. - ISSN 0022-2860.
Внешние системы:	DOI: 10.1016/j.molstruc.2016.03.009; WoS: 000383296700017;
Реферат:	eng: The mechanisms of temperature and high pressure phase transitions have been studied by Raman spectroscopy. Room temperature (295 K) experiments under high hydrostatic pressure up to 3.6 GPa for (NH4)(2) MoO2 F-4 have been carried out. Experimental data indicates a phase transition into a new high-pressure phase for (NH4)(2) MoO2 F-4 at 1.2 GPa. This phase transition is related to the ordering anion octahedron groups [MoO2 F-4](2) and is not associated with ammonium group. Raman spectra of small non-oriented crystals ranging from 10 to 350 K have been observed. The experiment shows anion groups [MoO2 F-4](2-) and ammonium in high temperature phase are disordered. The phase transition at T-1 = 269.8 K is of the first-order, close to the tricritical point. The first temperature phase transition is related to the ordering anion octahedron groups [MoO2 F-4](2-). Second phase transitions T-2 = 180 K are associated with the ordering of ammonium. The data presented within this study demonstrate that 2D correlation analysis combined with traditional Raman spectroscopy are powerful tool to study phase transitions in the crystals. (C) 2016 Elsevier B.V. All rights reserved.
Ключевые слова:	DISORDER; (NH4)(2)WO2F4; OXYFLUORIDE; DIAGRAMS; Two-dimensional correlations; Raman high-pressure; Phase transitions; Oxyfluorides;
Издано:	2016
Физ. характеристика:	с.125-130