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.