Evolution of rutile TiO 2 coating layers on lamellar sericite surface induced by Sn 4+ and the pigmentary properties

Abstract

Rutile TiO 2-coated sericite powders were prepared by the chemical deposition method starting from lamellar sericite and TiCl 4 in the presence of Sn 4+. After calcination at 850 °C for 4 h, TiO 2 nanolayers in rutile phase were formed on the sericite surfaces. The presence of Sn 4+ induced the phase transformation of amorphous to rutile TiO 2, giving the formation of TiO 2 nanolayers composed of small-sized rutile TiO 2 nanoparticles. XPS analysis shows that Sn 4+ cations were anchored at the sericite surfaces by formation of Al–O–Sn and Si–O–Sn bonds, and the aluminum and silicon sites on the sericite surfaces were dominantly occupied by Sn 4+ cations. TiO 2 coating layers were subsequently anchored at the sericite surfaces via Ti–O–Sn bonds. The TiO 2-coated sericite powders had higher light scattering indexes than the naked sericite powders. The brightness, whiteness, and light scattering index of the rutile TiO 2-coated sericite powders were slightly higher than those of the anatase TiO 2-coated sericite powders.