Occurrence of Ferromagnetic Behavior in ZrO2 by Ni Substitution Beyond x=0.01

Abstract

A series of Zr1-xNixO2 nanocrystalline powders were synthesized by chemical route and then calcined at 750 degrees C for 5 h. A mixed phase of monoclinic and tetragonal phase of ZrO2 has been observed in XRD patterns and Raman studies. The tetragonal phase of ZrO2 increases up to a Ni concentration of x = 0.025 and thereafter suppression of the tetragonal phase is observed with the increase in monoclinic phase of ZrO2. At lower concentration of Ni of x = 0.01, the material manifests with diamagnetic property and then a diamagnetic to ferromagnetic transition is established at above than x = 0.01. The saturation magnetization increases with increase in Ni concentration up to x = 0.025 and then decreases for Ni concentration of x = 0.03 in Ni substituted ZrO2. The sudden fall in saturation magnetization in Zr0.97Ni0.03O2 arises due to the superexchange interactions between two neighboring Ni2+ ions which lead to antiferromagnetism in the material and suppress the ferromagnetic ordering.