PHASE TRANSITIONS IN THE ORGANIC MONOPHOSPHATE NH3(CH2)6NH3 HPO4.2H2O

The organic monophosphate NH3(CH2)6NH3 HPO4.2H2O exhibits two phase transitions at 337 and 358 K : Phase I – 337 K → Phase II – 358 K → Phase III. These transitions were characterized by differentiel scanning calorimetry which shows two anomalies, Raman and infrared spectra, in the frequency range 300-1600, 400-4000 cm -1 respectively, at different temperatures. An assignment of bands due to internal modes is proposed. The spectral data are used for discussing the nature of structural and order-disorder phase transitions.