Electroless deposition of Ni on template of halloysite and its magnetic property

Halloysite template, a ceramic substrate, is of a hollow cylindric structure, on which the fine Pd nanoparticles are uniformly formed by the reduction of palldate chloride to initiate electroless deposition. The electroless deposition of Ni is catalyzed by the Pd particles, which results in a uniform layer of Ni-P alloy on halloysite. The alloy is of a nanocrystalline structure, of which the average diameter is about 6 nm. After being heat-treated at 400 ℃, it contains both Ni and Ni12P5 crystal, meanwhile, the Ni crystal gets larger with an average size of 51.9 nm.The content of phosphorous in the Ni layer has a great influence on crystal structure. The metallized halloysite has a higher inherent coercive force, and a much lower saturation magnetization in its as-plated state, while after heattreatment, the inherent coercive force decreases drastically. These magnetic properties have great relationship with the superparamagnetism of Ni nanocrystalline and the stress anisotropy in Ni layer.