Options
1998
Conference Paper
Titel
Dilatometric measurements of phase-stabilized ammonium nitrate (CuPSAN) performed by x-ray diffraction
Abstract
NH4NO3 is used as an oxidizer in solid propellants and gas generators. Its use is hindered by the vol. changes caused by phase transitions of the polymorphic substance under storage conditions. Cu(NH3)2 was incorporated into the NH4NO3 lattice to improve the phase behavior. The thermal expansion and the phase transitions of materials with Cu(NH3)2 contents corresponding to 7% CuO were measured with temp.-resolved x-ray diffraction. Series of measurements were performed, while the samples were heated with the temp. programs 20/100/-70/100 and 20/143/-70/20.degree.. The series were evaluated by Rietveld refinement yielding thermal expansion curves of the phases, which were identified by the known diffraction patterns. In temp. regions with coexisting phases Rietveld refinement was used for quant. phase anal. The obtained data det. unambiguously the stability ranges and the thermal expansion of the phases. They show that the stability of the room temp. phase IV and of phase II is extended to lower temps. Compared to pure AN the elementary cell of phase V of CuPSAN approaches a tetragonal structure like phase II.