Guilherme M. Santos, Daniel M. Silva, Valdirlei F. Freitas, Gustavo S. Dias, Adelino A. Coelho, M. Pal, Ivair A. Santos, Luiz F. Cótica, Ruyan Guo e Amar S. Bhalla
Ferroelectrics – Volume: 460; Issue: 1; Pages: 108-116; DOI: 10.1080/00150193.2014.875332
The lead-free AlFeO3-based compounds are attractive multiferroic materials, as those present piezoelectricity and ferrimagnetism at low temperatures. In this work the synthesis and ferroic properties of AlFeO3-based ceramics were investigated. Stoichiometric proportions of the precursors – α-Fe2O3 and α-Al2O3 – were milled and sintered to obtain AlFeO3 ceramics. Also, AlFeO3 ceramics doped with 2at% of Nb2O5 or MnO2 were sintered in oxygen flow at 1700 K. The crystal structure of the samples was studied by X-ray diffraction. The diffractograms were refined by the Rietveld method. The results obtained from refinements showed an orthorhombic symmetry with space group Pna21. Dielectric, ferroelectric and magnetic investigations suggested a magnetoelectric coupling between the electric and magnetic orderings at temperatures below ∼ 160 K for AlFeO3, Al(Fe0.98Nb0.02)O3 and Al(Fe0.98Mn0.02)O3, where the compositions show the ferromagnetic and ferroelectric ordering.