Magnetic moments of Ti cations in Ti-doped Ni0.68Fe2.32O4 spinel ferrites

Two series of Ti doped Ni0.68Fe2.32O4 ferrite samples with a single cubic spinel phase were prepared using conventional ceramic methods. A transition temperature, TN, was found when the Ti doping level was x > 0.15, below which temperature the magnetization of the samples abruptly decreased with decreasing measurement temperature rather than rising or remaining nearly constant as in samples with less doping. It was found that TN increased with increasing applied magnetic field. These phenomena indicated that with Ti doping an additional antiferromagnetic structure arises in the traditional spinel phase of ferrites and therefore that Ti ions have magnetic moments rather than as Ti4+ cations which has zero moment.