Electrophoretic Deposition of TiO2/Er3+ Nanoparticulate Sols

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• 作者：Mario Borlaf ; Mar铆a Teresa Colomer ; F谩tima Cabello ; Rosalia Serna ; Rodrigo Moreno
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：February 14, 2013
• 年：2013
• 卷：117
• 期：6
• 页码：1556-1562
• 全文大小：507K
• 年卷期：v.117,no.6(February 14, 2013)
• ISSN：1520-5207

文摘

TiO₂ and TiO₂/Er³⁺ nanoparticulate sols were obtained by the colloidal sol鈥揼el route. Thanks to the combination of three optical techniques (laser diffraction, LD, dynamic light scattering, DLS, and multiple light scattering, MLS), the peptization time was quantified, demonstrating that erbium(III) ions retard the process. The isoelectric point of TiO₂ shifts up to higher pH's when Er³⁺ ions are present, which suggests that they are adsorbed onto the surface of the TiO₂ nanoparticles. Moreover, the viscosity of the sols increases when the erbium(III) amount increases. The xerogels obtained from each sol were characterized by XRD and HRTEM, obtaining in all cases anatase as the major phase, although traces of brookite were also present. In the EPD experiments, the addition of ethanol was necessary to reduce the water hydrolysis and facilitate the drying process. As a result, transparent thin films were obtained at short times and low current densities and opal films for larger current densities and deposition times; in addition, the thickness, measured by ellipsometry, increased gradually, but the refractive index did not change significantly (1.9鈥?). The topography profile of the films and the particle size were obtained by atomic force microscopy (AFM), giving similar values to those measured by DLS, indicating that the addition of ethanol helps to maintain stabilization without further agglomeration or sedimentation.