Effect of cobalt on the magnetic properties of the LiFe1-xCoxO2 layered system (0 <= x <= 1)

Layered LiFe1-xCoxO2 was prepared in the whole composition range by ion-exc hange reaction in a molten eutectic mixture of LiCl and LiNO3 at 260 degree sC, The magnetic properties were studied by means of magnetic susceptibilit y and high-field magnetization measurements. Layered LiFeO2 exhibits a Neel temperature of T-N=20 K. Some cationic disorder is present but seems to ha ve no effect on the magnetic properties. The saturation magnetization and t he number of effective Bohr magnetons are consistent with the high spin sta te (S = 5/2) of the Fe3+ ion. A two sublattice model consisting of antiferr omagnetic order between ferromagnetic layers is proposed with an estimation of the ferro- and antiferromagnetic interactions. Replacing iron by cobalt leads to an increase of the Weiss temperature theta up to x = 0.4 but at t he same time the antiferromagnetic long-range order is destroyed. The effec t of cobalt on the superexchange interactions is also discussed. (C) 2000 A cademic Press.