Preparation of highly dispersed core-shell α′′-Fe16N2/SiO2 particles using hydroxyapatite as a sintering prevention layer

Abstract

Highly dispersed core-shell α′′-Fe16N2/SiO2 particles were prepared using hydroxyapatite (HAp) as the sintering prevention layer. HAp was effective as anti-sintering agent, and could be dissolved by solutions with wide pH range. The α′′-Fe16N2 phase was formed by reduction and nitridation, in spite of the presence of SiO2 and HAp. HAp was effective to prevent the aggregation of the core-shell α′′-Fe16N2/SiO2 particles resulted from the elimination of the surface Si-OH of silica shell layer. The HAp was successfully removed using the citric acid without the degeneration of the SiO2 shell layer and α′′-Fe16N2 core particles.