Structural and magnetic properties of the (Bi2-xPrx)Ru2O7 pyrochlore solid solution (0 <= x <= 2)

Siwar Zouari (1) , Rafik Ballou (2) , Abdelwaheb Cheikh-Rouhou (1) , Pierre Strobel (3)

1 Laboratoire de Physique des Matériaux
2 NEEL - MagSup - Magnétisme et Supraconductivité
3 NEEL - MRS - Matériaux, Rayonnements, Structure

We report a detailed study of structural and magnetic properties of the pyrochlore-type (Bi2-xPrx)Ru2O7 series. Eleven compositions with 0 ≤ x ≤ 2 were prepared by solid state reaction at 1050°C and found to form a solid solution in the whole range of compositions. Structural refinements from X-ray powder diffraction data by the Rietveld method show that the main variation concerns the ruthenium site. Ru-O distances increase and the Ru-O-Ru angle (bridging corner-sharing Ru-O octahedra) decreases with increasing praseodymium content, in agreement with the metal-semiconductor transition observed previously in this system. Magnetic measurements show that the metallic Pauli paramagnetism of Ru in Bi2Ru2O7 evolves to a magnetism of localized low spin moments coexisting with the magnetism of Pr3+ cations moments. Strong magnetic correlations are present at high Pr content, as illustrated by a Néel temperature of -224 K for Pr2Ru2O7. However no evidence of a magnetic ordering was found, suggesting that the end compound Pr2Ru2O7 of the series might stabilize a spin liquid phase.

Mots clés: oxide materials; rare-earth compounds; pyrochlore structure; magnetic measurements

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

Siwar Zouari, Rafik Ballou, Abdelwaheb Cheikh-Rouhou, Pierre Strobel. Structural and magnetic properties of the (Bi2-xPrx)Ru2O7 pyrochlore solid solution (0 <= x <= 2). Journal of Alloys and Compounds, 2009, 476 (1-2), pp.43-48. ⟨10.1016/j.jallcom.2008.09.106⟩. ⟨hal-00347221⟩