New Ferromagnetic La3Co2TaO9 double perovskite: Structural and Magnetic Properties

FUERTES, V.C; BLANCO, M.C.; FRANCO, D.G.; PANNUNZIO MINER, E.V.; SANCHEZ, R.D.; FERNANDEZ-DÍAZ, M.T.; CARBONIO, R.E.

PHYSICA B - CONDENSED MATTER

Elsevier

Lugar: Londres; Año: 2008

0921-4526

The new double perovskite La3Co2TaO9 has been prepared by a solid-state procedure. The crystal and magnetic structures have been studied from X-ray (XRPD) and neutron powder diffraction (NPD) data. Rietveld refinements were performed in the monoclinic space group P21/n. The structure consists of an ordered array of alternating B’O6 and B”O6 octahedra sharing corners, tilted along the three pseudocubic axes according to the Glazer notation a-b-c+. Rietveld refinements show that at RT the cell parameters are a = 5.6005(7) Å, b = 5.6931(7) Å, c = 7.9429(9) Å and b = 89.9539(7)º, and the refined crystallographic formula can be written as La3(Co)2d(CoTa)2cO9. Magnetization measurements and low-temperature NPD data show that the perovskite is a ferromagnet with TC= 72K. At high T it follows the Curie-Weiss law with an effective magnetic moment of 3.82µB per Co ion which is very close to spin only Co2+ (HS)