The Ba₂LnFeNb₄O₁₅ “tetragonal tungsten bronze”: Towards RT composite multiferroics

Michaël Josse (1) , Olivier Bidault (2) , François Roulland (1) , Elias Castel (1) , Annie Simon (1) , Dominique Michau (1) , Régnault von Der Mühll (1) , Olivier Nguyen (1) , Mario Maglione (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 LPUB - Laboratoire de Physique de l'Université de Bourgogne

Several Niobium oxides of formula Ba_2LnFeNb_4O_{15} (Ln = La, Pr, Nd, Sm, Eu, Gd) with the Tetragonal Tungsten Bronze (TTB) structure have been synthesised by conventional solid-state methods. The Neodymium, Samarium and Europium compounds are ferroelectric with Curie temperature ranging from 320 to 440K. The Praseodymium and Gadolinium compound behave as relaxors below 170 and 300 K respectively. The high temperature magnetic susceptibility of the Praseodymium, Neodymium, Samarium, Europium and Gadolinium compounds indicate that they are ferro or ferrimagnetically ordered below Curie temperatures ranging from 680 to 720K. Both ferroelectric and magnetic hysteresis loops are reported at room temperature, thus confirming the multiferroic behaviour of these compounds. Crystal-chemical analysis suggests a close relationship between the distortion of the TTB framework induced by the rare earth and the multiferroic properties.

Mots clés: Solid state Chemistry; Crystal-chemistry; Tetragonal tungsten bronze; Dielectric properties; Magnetic properties; Multiferroic properties; Composites

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Michaël Josse, Olivier Bidault, François Roulland, Elias Castel, Annie Simon, et al.. The Ba₂LnFeNb₄O₁₅ “tetragonal tungsten bronze”: Towards RT composite multiferroics. Solid State Sciences, 2009, 11 (6), pp.1118-1123. ⟨10.1016/j.solidstatesciences.2009.02.015⟩. ⟨hal-00175326⟩