Claudine Follet-Houttemane

The Bi2O3–Sm2O3 system: phase diagram and electrical properties

The (Bi2O3)1 –x–(Sm2O3)x system (0 ≤x≤ 0.65) was investigated by means of X-ray diffractometry, differential thermal analysis, impedance spectroscopy and e.m.f. measurements. The corresponding equilibrium solid-phase part of the diagram is proposed. The most striking feature is the existence of a very large domain of a δ Bi2O3 f.c.c.-type solid solution. By air-quenching from this domain two different phases were obtained: for 0.03 ≤x≤ 0.07, the room-temperature quenched phase exhibits tetragonal symmetry, changing to cubic for greater values of x. Both these phases are metastable and decompose into equilibrium phases on annealing. This transformation is always accompanied by a significant decrease in the electrical conductivity.

Catalytic decomposition of N2O over Ni and Mg-magnetite catalysts

The total decomposition of N2O was performed on the partially nanocrystalline substituted MxFe3−xO4 magnetite (M2+ = Ni2+ and Mg2+ with x = 0–1). The given results showed that the partial incorporation of Fe2+ by Ni2+ and Mg2+ into Fe3O4 spinel frameworks led to a significant amelioration in the catalytic activity for the N2O catalytic reaction. Furthermore, the catalytic activity of synthesized substrates depended on the Fe2+ substitution amount by Ni2+ and Mg2+ cations. The N2O conversion reached 20% (chemical regime) over the Ni0.75Fe2.25O4 and Mg0.58Fe2.42O4 catalysts at 395 and 404 K for N2O (5000 ppm), respectively. A relative increase of decomposition temperatures was observed after O2 addition. Moreover, other results show that the N2O conversion shifted to higher temperatures at high space velocities.

Catalytic Decomposition of Ammonium Dinitramide (ADN) as High Energetic Material over CuO-based Catalysts

CuO supported on a La2O3-doped alumina catalyst was prepared and tested in the decomposition process of an ADN–water energetic propellant. The decomposition products were investigated via on-line analysis. Moreover, CuO/Al2O3–La2O3 shows better results of ADN decomposition in comparison with CuO/Al2O3. Both catalysts were characterized by physico-chemical techniques.