Phase Transitions and Lattice Dynamics of Ammonium Nitrate

Abstract

Abstract Advanced evaluation techniques as Rietveld refinement applied to series of temperature resolved X‐ray diffraction measurements, provide an improved insight into the lattice dynamics. The transition paths of ammonium nitrate are clearly defined and coexisting phases are quantitatively determined. The curves for the elementary cell parameters of the different phases as a function of temperature exhibit hitherto unknown details and elucidate expansion and transition mechanisms. They are used for the calculation of the volume changes during the transitions and the volumetric and linear expansion coefficients.