Transition of ZnZrF6·4H2O to ZnZrF6·5H2O and patterns of structural transformations. N.A. DIDENKO, E.I. VOIT, K.A. SAYANKINA

Abstract

Transition of ZnZrF6·4H2O to ZnZrF6·5H2O and patterns of structural transformations. N.A. DIDENKO, E.I. VOIT, K.A. SAYANKINA (Institute of Chemistry, FEB RAS, Vladivostok).

Interaction of crystalline hydrate of ZnZrF₆∙4H₂O with water vapors from the air was studied by methods of Raman spectroscopy and XRD. It is shown that the compound ZnZrF₆∙4H₂O at 22–23 °C is unstable in the atmosphere of moist air (ρH₂O = 0.73–0.84 kPa). It has been found that under these conditions the transition of ZnZrF₆∙4H₂O → ZnZrF₆∙5H₂O takes place in two stages. At first, the starting compound adsorbs water and forms the hydrate ZnZrF6∙6H2O. And then the hexahydrate dehydrates rather quickly to ZnZrF₆∙5H₂O, due to the presence of structural distortions and defects in the crystal lattice of the high-water compound. A possible mechanism of structural transformations during ZnZrF₆∙4H₂O → ZnZrF₆∙6H₂O → ZnZrF₆∙5H₂O transitions is proposed.