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RESEARCH PRODUCT
Solid-State Transition Mechanisms of Ammonium Nitrate Phases IV, III, and II Investigated by Simultaneous Raman Spectrometry and Differential Scanning Calorimetry
Mauno E. E. Harjusubject
Phase transitionChemistry010401 analytical chemistryAnalytical chemistryCalorimetryMass spectrometry01 natural sciences0104 chemical sciencesCalorimeter010309 opticssymbols.namesakeDifferential scanning calorimetryPhase (matter)0103 physical sciencesX-ray crystallographysymbolsRaman spectroscopyInstrumentationSpectroscopydescription
The solid-state transition mechanisms of ammonium nitrate IV, III, and II were studied by measuring samples simultaneously by Raman spectrometry and differential scanning calorimetry (DSC). The Raman instruments were a Fourier transform Raman spectrophotometer and triple monochromator Raman spectrophotometer with charge-coupled-device (CCD) detector. The spectral data of the transitions were collected simultaneously with the calorimetric data in the temperature-scanning mode of the calorimeter and then isothermally between transitions. The phase transition from phase IV to phase III occurred through an intermediate phase II*, whose lifetime was seven minutes maximum when the onset temperature of the reaction was close to the phase-transition IV → II onset temperature. It is concluded that there is always an intermediate phase II* between IV and III. Simultaneous Raman measurements are shown to be an effective tool for interpreting complex DSC curves.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1993-11-01 | Applied Spectroscopy |