Formation of uniform TiO2 nanoshell on α-alumina nanoplates for effective metallic luster pigments

Abstract

To synthesize non-corroding effect pigment appearing metallic silver in color, we coated uniform anatase TiO2 nanoshell via sol-gel chemistry. Under the reaction condition using 3M TiCl4 aqueous solution: deionized water: HCl solution=0.75mL: 20 mL: 0 mL, ∼50 nm-thick smooth TiO2 nano-shell was fully coated on the surface of α-alumina nanoplates; consequently, the synthesized effect pigments exhibited similar lustering effect and structuring color to commercial effect pigment. Under relatively acidic condition and higher TiCl4 precursor concentration condition (3 M TiCl4 aqueous solution: deionized water:HCl solution=0.75mL: 20 mL: 0.05mL for acidic condition and 1.0 or 1.5mL: 20 mL: 0 mL for higher TiCl4 precursor concentration condition), rougher TiO2 shell was formed.