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Crystal and magnetic structure of piezoelectric, ferrimagnetic and magnetoelectric aluminium iron oxide FeAlO3 from neutron powder diffraction

Bourée, Françoise and Baudour, Jean-Louis and El Badraoui, E. and Musso, Jean and Laurent, Christophe and Rousset, Abel Crystal and magnetic structure of piezoelectric, ferrimagnetic and magnetoelectric aluminium iron oxide FeAlO3 from neutron powder diffraction. (1996) Acta Crystallographica Section B: Structural Science, B52 (2). 217-222. ISSN 0108-7681

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Official URL: http://dx.doi.org/10.1107/S0108768195010330

Abstract

The crystal structure of FeA103 has been determined at T = 298 K by neutron diffraction, using polycrystalline samples prepared in a high state of purity. The space group is Pna21, Z = 8; a = 4.9839(1), b = 8.5544(2), c = 9.2413(2)A,. The structure, which is isomorphous to that of FeGaO3, can be described as a double combination of hexagonal and cubic closed packing of oxygen ions. There are four different cation sites labelled Fel, Fe2 (predominantly occupied by iron), All and AI2 (predominantly occupied by aluminium). The oxygen environment of A11 forms an almost regular tetrahedron. The other sites have a distorted octahedral environment, especially irregular for Fel and Fe2. The fractions~ of iron ions over the four cation sites are:f1 = 0.78 (1), f2 = 0.76(1), f3 = 0.10(1) and f4 = 0.34(1). Neutron diffraction at T = 30K reveals a classical Nrel ferrimagnetism, the direction of easy magnetization being a, with strong '180 ° cation-anion-cation' superexchange antiferromagnetic interactions Fel-O-Fe2 and Fel-O-AI2 (AI2 being a site occupied by 0.34 Fe). The Nrel sublattices are A = Fel + All and B = Fe2 + AI2. The average magnetic moment per atom is weak (3.4 + 0.3 #B) and the spontaneous magnetization at T = 30K is extremely weak: 0.38 + 0.17#B per atom. Piezoelectricity probably originates in the bond arrangement of the four tetrahedral All sites in the unit cell, each tetrahedron being oriented with an AI1---O bond parallel to the polar c axis.

Item Type:Article
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Commissariat à l'Energie Atomique et aux énergies alternatives - CEA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université du Sud Toulon-Var - USTV (FRANCE)
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Deposited By: cirimat webmestre
Deposited On:23 Jun 2014 10:57

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