New Ferromagnetic La3Co2TaO9 double perovskite: Structural and Magnetic Properties

V.C. FUERTES; M.C. BLANCO; D.G. FRANCO; J.M. DE PAOLI; E.V. PANNUNZIO-MINER; R.D. SÁNCHEZ; M.T. FERNÁNDEZ-DÍAZ; R.E. CARBONIO

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2009 vol. 404 p. 2717 - 2719

0921-4526

The new double perovskite La3Co2TaO9 has been prepared by a solid-state procedure.The crystal andmagnetic structures have been studied from X-ray powder diffraction (XRPD) and neutron powderdiffraction (NPD) data. Rietveld refinements were performed in the monoclinic space group P21/n.The structure consists of an ordered array of alternating BO6 and B'O6 octahedra sharing corners,tilted along the three pseudo cubic axes according to the Glazer notation a-b-c+. Rietveld refinementsshow that at RT the cell parameters are a=5.6005(7)A, b=5.6931(7)A, c=7.9429(9)A andbeta=89.9539(7), and there fined crystallographic formula of this double perovskite can be writtenas La2(Co)2d(Co1/3Ta2/3)2cO6. Magnetization measurements and low-temperature NPD data show thatthe perovskite is a ferromagnet with TC=72K. At high T it follows the Curie?Weiss law with an effectivemagnetic momento 3.82mB per Co ion which is very close to spin only Co2+ (HS).