Magnetic Properties of Disordered Li2Co2-xNix(MoO4)(3) (0 <= x <= 2) System with a Lyonsite Structure

摘要

We report on the magnetic properties of disordered Li2Co2 - xNix(MoO4)(3) (0 <= x <= 2) system with a lyonsite structure, where Li+, Ni2+, and Co2+ ions are distributed in a disordered manner in the trigonal prism and octahedral sites. All compositions were found to exhibit paramagnetic behavior at high temperature; the magnetic susceptibility was described by the modified Curie-Weiss law. The experimental effective moments were explained by spin and orbital contributions of the Co2+ ions and only the spin contribution for Ni2+ ions. The negative Curie-Weiss temperature theta indicates the existence of antiferromagnetic coupling for all compositions. At low temperature, the compounds with Co2+ ions (x = 0, 1, 1.6, and 1.8) exhibit a weak ferromagnetic state below 4 K due to intrinsic canting of antiferromagnetically coupled lattices. The compound containing only Ni2+ ions, Li2Ni2(MoO4)(3), exhibits a pure antiferromagnetic behavior.