A Study of the Composition, Ionic and Molecular Mobility, and Thermal Properties of Ammonium Pentafluoridozirconate Hydrates


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The effect of hydrate number on the structural changes, thermal properties, and ionic (molecular) mobility character in NH4ZrF5 ⋅ H2O, NH4ZrF5 ⋅ 0.75H2O crystal hydrates have been investigated by the methods of IR, Raman, nuclear magnetic resonance (NMR) (1H, 19F, including 19F MAS), and TG-DTA spectroscopy. Differences in crystal hydrate structures—anion structure, molecular state of water, and O–H⋅⋅⋅F, N–H⋅⋅⋅F hydrogen bond strengths—have been corroborated by IR and Raman spectroscopy data. Isotropic chemical shifts of magnetic inequivalent positions have been determined and attributed to crystal structures of the studied compounds by the method of 19F MAS NMR. It has been established that the removal of water molecules from NH4ZrF5 ⋅ H2O and NH4ZrF5 ⋅ 0.75H2O results in the transformation of chain or layered structures accompanied by the increase of the number of bridge bonds while retaining or increasing the dimensionality of the anion structural motif. According to the 1H NMR data, the NH\(_{4}^{ + }\) cation diffusion in NH4ZrF5 occurs only in the temperature range of 370–520 K.

Sobre autores

E. Voit

Institute of Chemistry, Far East Branch, Russian Academy of Sciences

Autor responsável pela correspondência
Email: evoit@ich.dvo.ru
Rússia, Vladivostok, 690022

A. Slobodyuk

Institute of Chemistry, Far East Branch, Russian Academy of Sciences

Email: evoit@ich.dvo.ru
Rússia, Vladivostok, 690022

N. Didenko

Institute of Chemistry, Far East Branch, Russian Academy of Sciences

Email: evoit@ich.dvo.ru
Rússia, Vladivostok, 690022

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