On the Phase Transitions in Hydrazinium(2+) Sulfate

The existence of a “diffuse” phase transition below room temperature has been confirmed in N2H6SO4 crystal by powder X-ray and DTA experiments. The transition temperature is very sensitive to the grain size. This size effect was discussed on the basis of the thermodynamic nucleation theory taking into account the interfacial energy between the high and the low temperature phases. The diffuse nature of the transition was interpreted by a theory proposed by Tobolsky et al. The spin-lattice relaxation times of 1H were redetermined and the nature of the cationic motion in each phase was discussed.