A Novel Two-Step Silica-Coating Process for Engineering Magnetic Nanocomposites

Abstract

A novel two-step silica-coating process, sol−gel followed by dense liquid coatings, is described. The maghemite surfaces coated with silica, using the two-step process, are characterized by X-ray photoelectron spectroscopy, electrokinetics, leaching test, and magnetization measurement. Compared with the single-step sol−gel or dense-liquid-coating process, the two-step process produces magnetic nanocomposites of the highest protection against acid attack at the lowest level of silica coatings with maximized magnetization.