The effect of Mg doping on the structural and physical properties of LuFe2O4 and Lu2Fe3O7

The structural and physical properties of the recently discovered electronic ferroelectric materials LuFe2O4 and Lu2Fe3O7 have been investigated for Mg substitution of Fe. X-ray diffraction data demonstrate that the lattice parameters in both systems change progressively with increasing Mg content, with a smaller unit cell volume on replacing Fe2+ by Mg2+. X-ray absorption near-edge spectroscopy experiments at the Fe K-edge show that the average Fe oxidation state is slightly increased along with Mg doping in Lu2Fe3O7 materials, consistent with isomorphous replacement of Fe2+ by Mg2+. Measurements of dielectric properties demonstrate that Mg doping could have an effect on the electron hopping energy between Fe2+ and Fe3+ ions. Transmission electron microscopy and magnetization analysis reveal that Mg doping in LuFe2O4 has a much greater influence than in Lu2Fe3O7 on both the charge ordering and the low-temperature magnetic properties