Coexistence of localized and itinerant electrons in the novel double perovskite Ba2Fe2/3Mo4/3O6

C.A. LÓPEZ; M.E. SALETA; J.C. PEDREGOSA; R.D. SÁNCHEZ; J.A. ALONSO; M.T. FERNÁNDEZ-DÍAZ

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2014 vol. 2014 p. 3555 - 3563

1434-1948

Abstract    Polycrystalline Ba2Fe2/3Mo4/3O6 double perovskite has been prepared by decomposition of citrate precursors and subsequent thermal treatment under reducing atmosphere. The crystal structure has been studied by combined X-ray and neutron powder diffraction (XRPD and NPD). At room temperature, the structure is cubic () with lattice parameter a = 8.0710(1) Å. It is unchanged between 3 K and 320 K. The crystallographic formula is Ba2[Fe0.14(2)Mo0.86(2)]4b[Fe0.52(2)Mo0.48(2)]4aO5.9(2). The mixed occupancy of Fe and Mo over the two octahedral 4a and 4b sites introduces structural disorder to the system. NPD, electron spin resonance (ESR), and magnetization measurements show spontaneous magnetization below TC = 310 K. The ESR behavior is associated with the presence of localized Fe3+ ions, while the transport properties (electrical conductivity, magnetoconductivity and Seebeck effect) suggest the presence of highly correlated electrons in a metallic band with disorder, which can be associate to the Mo t2g electrons. The coexistence of localized and itinerant electrons leads to a non-negligible magnetoresistance (MR) properties.