In this work, electrostatic force microscopy (EFM) is used to investigate the interface around a nanoparticle in terms of its properties viz. electric charge density and dielectric constant. Nanodielectrics composed of barium titanate (BaTiO3) nanoparticles embedded in epoxy matrix are used for the study. Phase shift images obtained from EFM experiments indicate the region occupied by an embedded particle in the matrix, as well as the presence of an interfacial region around it. In an earlier work [12], a finite element method (FEM) based 3-D electrostatic model was developed by the authors to computationally obtain the EFM phase shift in the interfacial region, and was used in conjunction with experimental data to estimate the dielectric constant and thickness of the interface. The possibility of charge on the particle surface and/or in the interfacial region around it, is investigated using the same model and methodology. Computational results indicate that the presence, magnitude and polarity of charge affect the EFM phase shift signal. Comparison of computational and experimental data, confirms the presence of an interfacial region around the particle with a dielectric constant higher than that of the bulk epoxy, and with negative charge present in it.

中文翻译：

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使用静电力显微镜检测纳米复合材料中纳米颗粒周围的电荷

在这项工作中，静电力显微镜 (EFM) 用于研究纳米颗粒周围界面的特性，即。电荷密度和介电常数。该研究使用了由嵌入环氧树脂基质中的钛酸钡 (BaTiO3) 纳米颗粒组成的纳米电介质。从 EFM 实验中获得的相移图像表明基质中嵌入粒子所占据的区域，以及它周围的界面区域的存在。在早期的工作 [12] 中，作者开发了一种基于有限元方法 (FEM) 的 3-D 静电模型，以计算获得界面区域的 EFM 相移，并结合实验数据来估计介电界面的常数和厚度。使用相同的模型和方法研究颗粒表面和/或其周围界面区域带电的可能性。计算结果表明电荷的存在、大小和极性会影响 EFM 相移信号。计算和实验数据的比较证实了粒子周围的界面区域的存在，其介电常数高于本体环氧树脂的介电常数，并且其中存在负电荷。