SÍNTESE DO ESPINÉLIO Al 2 MnO4 VIA REDUÇÃO COM H2

Abstract

Nanostructured oxides with interesting magnetic properties, such as the spinel Al2 MnO4 , can be synthesized through thermal decomposition of nitrate solution followed by thermal treatment under a reducing atmosphere. The present work can be understood as a study of the synthesis of Al2 MnO4 samples based on the H2 reduction of Al and Mn oxide mixtures, including a discussion of the effect of some important process variables over the kinetic behavior of the system, such as temperature and thermal treatment time. For the temperature range considered (1,073 K to 1,173 K) both the total reduction of manganese oxides to MnO, as well as the formation of spinel structures could be verified. At the beginning of the formation process, the spinel shows considerable cationic disorder (non-stoichiometric structure). The structure then evolves to the equilibrium stoichiometric form for higher process temperature and time.

Keywords

• Spinel; Al2 MnO4 ; Nitrates; H2 reduction.