CALORIMETRIC, THERMOANALYTICAL AND DIELECTRIC STUDIES OF PHASE TRANSITIONS IN AMMONIUM NITRITE.

Article abstract of DOI:10.1016/0038-1098(88)90976-3

Ammonium nitrite NH//4NO//2 has been studied by differential thermal analysis, calorimetry and dielectric measurement. A higher order phase transition was found at 276. 5 K. The enthalpy and entropy of transition are 1. 2 kJ mol** minus **1 and 4. 6 J K** minus **1 mol** minus **1, respectively. A peak of the dielectric constant, reaching 12 at 200 Hz, occurred at the transition temperature. The temperature dependence of the dielectric constant suggests that the low temperature phase is ferroelectric. A first order transition occurred at 347 K, of which a detailed study has been hampered by the decompositon of the sample