Multiferroic Behavior of Lead-free AlFeO₃ and Mn, Nb Doped Compositions

Abstract

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(Fe_0.98Nb_0.02)O₃ and Al(Fe_0.98Mn_0.02)O₃, where the compositions show the ferromagnetic and ferroelectric ordering.

Keywords:

• Ferroelectrics
• lead-free
• multiferroic magnetoelectrics
• magnetic properties

Acknowledgment

LFC also acknowledges UTSA under the INAMM/NSF program for hosting him.