Department of Mechanical Engineering and Material Science, Duke University, 144 Hudson Hall, Durham, North Carolina 27708, United States.
ACS Appl Mater Interfaces. 2013 Apr 10;5(7):2610-7. doi: 10.1021/am3031954. Epub 2013 Apr 1.
Ferroelectric surfaces can have very high surface charge densities that can be harnessed for manipulation of charged colloidal particles and soft matter in aqueous environments. Here, we report on the electrical double layer (EDL) formed by polarized ultrasmooth lead zirconium titanate (US-PZT) thin films in dilute electrolyte solutions. Using colloidal probe force microscopy (CPFM) measurements, we show that the ion distribution within the double layer can be changed by reversing the ferroelectric polarization state of US-PZT. The interaction force in dilute 1:1 electrolyte solution between the negatively charged probe and a positive surface charge (upward polarized) US-PZT thin film is attractive, while the interaction force is repulsive for a negative surface charge (downward polarized) film. We modeled these interactions with a constant-potential EDL model between dissimilar surfaces with the inclusion of a Stern layer. We report the surface potentials at the inner and outer-Helmholtz planes both for polarization states and for a range of ionic strength solutions. Effects of free-charge carriers, limitations of the analytical model, and effects of surface roughness are discussed.
铁电表面可以具有非常高的表面电荷密度，可以用于在水相环境中操纵带电胶体颗粒和软物质。在这里，我们报告了由极化的超平滑锆钛酸铅（US-PZT）薄膜在稀电解质溶液中形成的双电层（EDL）。使用胶体探针力显微镜（CPFM）测量，我们表明通过反转 US-PZT 的铁电极化状态可以改变双电层内的离子分布。在负探针和带正表面电荷（向上极化）US-PZT 薄膜之间的稀 1:1 电解质溶液中的相互作用力是吸引力，而对于带负表面电荷（向下极化）的薄膜，相互作用力是排斥力。我们使用包括斯特恩层在内的具有不同表面的恒定电位 EDL 模型对这些相互作用进行了建模。我们报告了极化状态和一系列离子强度溶液的内和外亥姆霍兹平面的表面电势。讨论了自由电荷载流子的影响、分析模型的局限性以及表面粗糙度的影响。
