AbstractThe effect of hydrate number on the structural changes, thermal properties, and ionic (molecular) mobility character in NH_4ZrF_5 ⋅ H_2O, NH_4ZrF_5 ⋅ 0.75H_2O 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 NH_4ZrF_5 ⋅ H_2O and NH_4ZrF_5 ⋅ 0.75H_2O 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 NH_4ZrF_5 occurs only in the temperature range of 370–520 K.
D¯s(*)D(*)
molecular state with
JP=1+
