Article ID Journal Published Year Pages File Type
143997 Advanced Powder Technology 2013 5 Pages PDF
Abstract

Magnetite nanoparticles have been prepared by electrooxidation of iron in water. Surface modifications have been conducted by coating the nanoparticles with silica by a one-step synthesis in dilute sodium silicate solution. The mean size of particles was approximately 10–30 nm for the uncoated particles and 9–12 nm for the coated particles. The results obtained from thermal gravimetric/differential thermal analysis (TG/DTA) revealed that the silica layer formed by the electrochemical method was stable and could serve as a protective layer. Annealing the nanoparticles at 550 °C for 30 min converts magnetite into maghemite for the silica-coated particles, and it further converts the uncoated particles into hematite. The conversions cause the saturation magnetization to decrease for all samples.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Silica-coated magnetite nanoparticles were successfully prepared by one-step method. ► We investigate the thermal stability of the silica-coated magnetite nanoparticles. ► The silica layer is stable under heating up to 550 °C. ► The silica layer can protect magnetite from being converted to other oxide species.

Related Topics
Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
Authors
, , , ,