Preparation and Electromagnetic Wave Absorption Properties of Core-Shell Ni/TiO sub(2) Microspheres

The composite microspheres with Ni cores and amorphous TiO sub(2) shells (NiiO sub(2)) were synthesized by a one-pot solvothermal method at 180[degrees]C for 15 h, which used nickel chloride hexahydrate as Ni source andtetrabutyl orthotitanate as Ti source. The Ni/TiO sub(2) core/shell composites were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX). A possible formation mechanism of core-shell Ni/TiO sub(2) was proposed. Furthermore, the microwave absorption properties of these microspheres were investigated in terms of complex permittivity and permeability. The minimum reflection loss is-29.5 dB at 14.4 GHz for a layer of 4.0 mm thickness. Such phenomenon is attributed to the synergy effect between magnetic loss of Ni core and dielectric loss of amorphous TiO sub(2) shell. The enhanced microwave absorption properties are also believed to be due to the unique coreshell structure. All results indicate that these NiiO sub(2) microspheres may be attractive candidate materials for electromagnetic wave absorption applications.