Synthesis And Characterization Of A Multiferroic BiMn2O5 System With Mullite Type Perovskite Structure Obtained By Solid State Reaction.

The synthesis of pure, single-phase, multiferroic materials is nowadays a big challenge since minute amounts of impurities may hinder their intrinsic magnetic and electrical properties. Among these materials, oxides with perovskite structures are of great importance since the presence of various available sites will determine the oxidation state of the magnetic cations while the existence of different magnetic sublattices will lead to a competition between ferromagnetic and antiferromagnetic interactions. It is then of great importance to carefully chose the synthesis method in order to obtain single-phase compounds.

The advanced oxide material BiMn2O5 was obtained by solid state reaction (RES) at low temperature. The material was then heat-treated at different temperatures (700°C/750°C and 800°C by 24 hours in each temperature. X Ray diffraction and EDX/MEV analysis showed the formation of a single-phase solid solution with composition BiMn2O5. This compound crystallizes in the (mullite type perovskite) orthorhombic space group Pbam, with lattice parameters: a = 7.56 Å, b= 8.53 Å, c= 5,76 Å[2]. The SEM/EDS analysis confirmed a good atomic percentage distribution near to 2:1 Mn:Bi.

The magnetic measurements for the samples obtained by ZFC/FC cycles show an antiferromagnetic response with TN near to 40 K one paramagnetic Curie-Weiss temperature (p) near to -279 K and effective magnetic moment (μeff = 6.38 μB). The results obtained for the samples synthesized by solid state reaction showed then this method is appropriate for to obtain monophasic samples.

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