Magnetic behavior of Ca2NiWO6 double perovskite

Polycrystalline Ca2NiWO6 double perovskite has been prepared by solid-state reaction at 1150 C. The crystal structure of this material has been confirmed by X-ray powder diffraction (XRD). At room temperature, the crystal structure is monoclinic, space group P21/n, with a=5.4061(2) A, b=5.5389(2) A, c=7.6895(3) A, β=90.232(2)o. Magnetic susceptibility and electron spin resonance experiments on Ca2NiWO6 show at high temperature a Curie-Weiss behavior with a θ=-75 K. From the Curie-Weiss behavior, the effective magnetic moment is 2.85μ B, which is in agreement with the presence of Ni2+ in the system. At low temperatures, below 52.5(0.2) K, the magnetic susceptibility shows antiferromagnetic behavior. From the experimental data and the mean field theory of antiferromagnetism we estimated the Ni interactions among the nearest Ni neighbors and the second nearest Ni neighbors