The effect of Mg doping on the structural and physical properties of LuFe₂O₄and Lu₂Fe₃O₇

Abstract

The structural and physical properties of the recently discovered electronic ferroelectric materials LuFe(2)O(4) and Lu(2)Fe(3)O(7) 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 Fe(2+) by Mg(2+). 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 Lu(2)Fe(3)O(7) materials, consistent with isomorphous replacement of Fe(2+) by Mg(2+). Measurements of dielectric properties demonstrate that Mg doping could have an effect on the electron hopping energy between Fe(2+) and Fe(3+) ions. Transmission electron microscopy and magnetization analysis reveal that Mg doping in LuFe(2)O(4) has a much greater influence than in Lu(2)Fe(3)O(7) on both the charge ordering and the low-temperature magnetic properties.