A. Goni et al., Unexpected substitution in the Li1-3xFexNiPO4 (0 < x < 0.15) solid solution. Weak ferromagnetic behaviour, J MAT CHEM, 10(2), 2000, pp. 423-428
Li1 - 3xFexNiPO4 (0 < x < 0.15) solid solution phases have been synthesized
by solid state reaction. X-Ray studies on polycrystalline samples show tha
t all phases are isostructural with the parent LiNiPO4 compound, crystalliz
ing in the orthorhombic system, space group Pnma. The evolution of the latt
ice parameters with the iron content follows Vegard's law. The IR spectra s
how split bands for the phosphate groups, in good agreement with the distor
tion observed in the crystal structure. The EPR spectra for all phases show
a broad band centred at zero field. The absence of a signal corresponding
to Fe3+ ions suggests the presence of Fe-III-Ni-II interactions strongly af
fected by the zero field splitting of the nickel(ii) ions. The magnetic beh
aviour of the Li1 - 3xFexNiPO4 (0 < x < 0.15) phases can be described as an
tiferromagnetic with the presence of weak ferromagnetism below the ordering
temperature. The magnitude of the remanent ferromagnetic moment is indicat
ive of the existence of iron clustering in the samples. The FeO6 octahedra
form finite chains in which the magnetic moments of the Fe3+ ions are antif
erromagnetically aligned with a small canting angle.