In this study, we synthesized a hollow structured core-shell β-FeOOH@SiO2 particles via etching treatment with mild basic solution. The rod shaped β-FeOOH particles were prepared by hydrolysis of FeCl3 as a raw material and subsequently coated with silica via sol-gel method. The hollow shell layer was fabricated by dissolution of SiO2 shell from core-shell β- FeOOH@SiO2 particles in certain NH4OH solution. We have been found that the thermal stability of a hollow SiO2 coating layer having a relatively low density is sufficiently maintained to a temperature at a very specific high temperature equivalent to common core-shell structure. Particularly, the crystal phase and morphology of core shell particles, which have a large effect on the chromaticity, were transferred at about 500 oC. Moreover, the chromaticity of the core-shell particles was not significantly decreased due to individual phase transition in the state of being trapped in the coating layer.

Keywords: Inorganic pigment, Hollow structure, Core-shell, Coloration, β-FeOOH