Experimental and theoretical methods to study structural phase transition mechanisms in K{sub 3}WO{sub 3}F{sub 3} oxyfluoride

• Published in: Journal of solid state chemistry Vol. 218
• Main Authors: Krylov, A.S., Sofronova, S.N., Kolesnikova, E.M., Ivanov, Yu.N., Sukhovsky, A.A., Goryainov, S.V., Ivanenko, A.A., Shestakov, N.P., Kocharova, A.G., Vtyurin, A.N.
• Format: Journal Article
• Language: English
• Published: United States 15-10-2014
• Subjects: COMPARATIVE EVALUATIONS; CRYSTALS; FERROELECTRIC MATERIALS; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; OXYFLUORIDES; PHASE TRANSFORMATIONS; RAMAN SPECTROSCOPY
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2014.05.028

The results of structural phase transitions mechanisms study in K{sub 3}WO{sub 3}F{sub 3}oxyfluoride are represented by different experimental and theoretical methods. The structural phase transition anomalies at T{sub 1}=452 K and T{sub 2}=414 K of Raman and IR spectra have been analyzed. Using vibrational spectroscopy methods, the NMR-experiment has been done to clarify the nature of found phase transitions: displacive types or order-disorder types. The model of “disordered” crystal was proposed, and the results of lattice dynamics calculation in frameworks of the generalized Gordon–Kim method of ordered (R3) and “disordered” crystals were compared. The high pressure phases were studied by the Raman technique too. - Graphical abstract: (1) Two possible configuration of octahedra. (2). All phases Raman lines of octahedra. (3) All phases IR lines of octahedra. (4) NMR spectra of all phases. - Highlights: • The results of study oxyfluoride K{sub 3}WO{sub 3}F{sub 3} are represented by Raman, IR, NMR technique. • The high pressure phases were studied by the Raman technique. • The anionic octahedra [WO{sub 3}F{sub 3}]{sup 3−} are not ordered below the both phase transitions. • The ferroelectric phase is realized due to the shift of atoms without F/O ordering. • Both of found phase transitions are close to the second order.