Facile Preparation and Electromagnetic Properties of Core-Shell Composite Spheres Composed of Aloe-like Nickel Flowers Assembled on Hollow Glass Spheres

Aloe-like nickel flowers assembled on hollow glass spheres are successfully synthesized by a facile low-temperature hydrothermal reduction process, and thus novel 3D core-shell composite hollow spheres with hierarchical structures are fabricated. By properly tuning the process conditions and the component of the reaction solution, a series of composite spheres with gradient in morphologies of the shell layer can be prepared. On the basis of a series of contrast experiments, the probable formation mechanism of the core-shell hierarchical structures is proposed. The magnetic properties of the products are studied, and the results demonstrate that the composite spheres present ferromagnetic properties related to the special microstructures. Because of the conductive and ferromagnetic behavior of the nickel shells, the composite spheres possess morphology-dependent microwave absorption properties and may have some promising applications in low-density magnetic materials and microwave absorbers. This work provides an additional strategy to prepared core-shell composite spheres with tailored shell morphology and electromagnetic properties.