Deposition feature of Ni nanoparticles on halloysite template and magnetic properties of the composite

A novel cermet composite with Ni nanoparticles deposited on a hollow cylindrical halloysite template is fabricated by electroless plating. Ni nanoparticles have a uniform distribution on the template, and their average diameter is mainly in the range of 20-30 nm. The halloysite template will be beneficial to make the Ni nanoparticles achieve high stability and well-dispersed state. Different heat treatment temperatures have a great effect on the crystal structure of Ni nanoparticles and the magnetic properties of the composite. With the heat-treated temperature increase, Ni nanoparticles gradually become crystallized, and the composite values of inherent coercive force (iHc), saturated magnetization (Ms), and residual magnetization (Mr) increase respectively. After complete crystallization of Ni nanoparticles at 673 K, the composite has the maximum values of iHc (253.6 Oe), MS (57.37 emu/g), and Mr (21.64 emu/g). The sum contribution of the magneto-crystal line anisotropy, single magnetic domain effect, and the pinning effect of multiple-twinned planar defects in Ni nanoparticles would result in the high value of Me. The new nanosized cermet composite will be at such an advantage for its practicable fabrication method, higher coercive force, high stability, and low cost that it would have great potential to be utilized to design and prepare magnetic materials.