At high temperature, the roles of NH 4 and H 2 O in (NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O and (NH 4 ) 2 Zn(SO 4 ) 2 ·6H 2 O single crystals were investigated using a pulse NMR spectrometer. Temperature was shown to have a significant influence, causing changes in the deformation of NH 4 and H 2 O. From the 1 H NMR and 14 N NMR spectrum, the forms of environment surrounding 14 N in NH 4 groups is more important than the loss of H 2 O groups. NMR studies indicate that NH 4 + ions in Tutton salts play an

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... mportant role in the changes of the crystal structure at high temperatures.