THE ORIGIN OF FERROMAGNETISM IN Ni-DOPED ZnO AND SnO₂

Abstract

We present a detailed study of the ferromagnetism in nano- Ni -doped SnO 2 and ZnO . It is shown that the ferromagnetic behavior is not an intrinsic property of the systems but rather associated with the presence of n Ni particles in both matrices. The ferromagnetic transition of all Ni -doped samples is at 631(2) K, the same as the T C value for bulk Ni and nano- Ni powder. The saturation moments of the nano- Ni -doped samples scale with the Ni concentration and are much lower than that of pure Ni . This is due to the large surface area of nano- Ni particles which are partially oxidized due to nano- NiO . 119 Sn Mössbauer spectroscopy studies on Sn 0.96 Ni 0.04 O 2 do not show any transferred hyperfine field on the Sn nuclei, confirming that the magnetic properties stem from a different phase.