Evolution of TiO₂ coating layers on lamellar sericite in the presence of La³⁺ and the pigmentary properties

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• 作者：Min Ren ; Hengbo Yin ; Aili Wang ; Chen Ge ; Chunyan Liu ; Longbao Yu ; Tingshun Jiang ; Yumin Liu ; Ying Hang
• 关键词：Lamellar sericite ; TiO₂ coating ; Lanthanum ; Pigmentary property
• 刊名：Applied Surface Science
• 出版年：2008
• 出版时间：15 September 2008
• 年：2008
• 卷：254
• 期：22
• 页码：7314-7320
• 全文大小：1078 K

文摘

TiO₂-coated sericite powders were prepared by the chemical deposition method starting from lamellar sericite and TiCl₄ in the presence or absence of La³⁺ cations. After calcination at 900 °C for 1 h, the resultant TiO₂ nanoparticles on the sericite surfaces existed in anatase phase. The light scattering indexes of the TiO₂-coated lamellar sericite powders were dozens of times higher than that of the naked lamellar sericite powders. The presence of La³⁺ in the deposition solution was beneficial to the formation of the small-sized anatase TiO₂ nanoparticles, resulting in the formation of the dense and uniform island-like TiO₂ coating layers in a large range of the weight ratios of TiO₂ to sericite from 5 % to 20 % . The TiO₂-coated lamellar sericite powders prepared in the presence of La³⁺ had higher light scattering index than that prepared in the absence of La³⁺. XPS analysis shows that when La³⁺ cations were absent in the reaction solution, TiO₂ coating layers anchored at the sericite surface via the Ti–O–Si and Ti–O–Al bonds. The presence of La³⁺ cations caused the formation of Si–O–La and Al–O–La bonds at the sericite surface and Ti–O–La bond at the surface of TiO₂ coating layers. After coating TiO₂ on the sericite surface, the yellowness of the TiO₂-coated sericite powders obviously increased and the brightness slightly decreased.