Romain Berthelot

Synthesis and characterization of O3-Na{sub 3}LiFeSbO{sub 6}: A new honeycomb ordered layered oxide

Abstract A new compound Na3LiFeSbO6 has been synthesized by conventional solid state methods and investigated using X-ray diffraction, DC magnetic susceptibility, 57Fe Mossbauer spectroscopy and optical measurements. This compound crystallizes in a monoclinic unit cell and is related to a family of honeycomb ordered layered oxide materials where Na+ fills octahedral interlayer sites between Li1/3Fe1/3Sb1/3O2 slabs of edge sharing octahedra. Each SbO6 octahedron is surrounded by LiO6 and FeO6 octahedra creating a honeycomb arrangement within the slabs. Powder X-ray diffraction indicates the presence of stacking faults. This compound exhibits Curie–Weiss behavior at high temperatures and the effective magnetic moment verifies the presence of high spin Fe3+. The 57Fe Mossbauer spectroscopy confirms Fe3+ in an octahedral position and indicates disorder in the arrangement of LiO6 and FeO6 octahedra in the Li1/3Fe1/3Sb1/3O2 slabs.

Synthesis and characterization of Sr{sub 2}Ir{sub 1-x}M{sub x}O{sub 4} (M=Ti, Fe, Co) solid solutions

Abstract The effects of Ti, Fe and Co substitutions for Ir on the structure and on the physical properties of Sr 2 IrO 4 are investigated. A complete solid solution Sr 2 Ir 1− x Ti x O 4 is obtained while both Fe and Co doping are relatively limited. In each case however, the c -axis cell parameter and the initial IrO 6 octahedra tilting decreases with substitution. Doping with Ti, Fe and Co results in a decrease of the magnetic susceptibility and in an increase in the paramagnetic effective moment for Co and Fe doped samples and a suppression of the weak ferromagnetic ordering observed for Sr 2 IrO 4 .