Formation and Grain Analysis of Spin-Cast Magnetic Nanoparticle Monolayers

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• 作者：Aaron C. Johnston-Peck ; Junwei Wang ; Joseph B. Tracy
• 刊名：Langmuir
• 出版年：2011
• 出版时间：April 19, 2011
• 年：2011
• 卷：27
• 期：8
• 页码：5040-5046
• 全文大小：1295K
• 年卷期：v.27,no.8(April 19, 2011)
• ISSN：1520-5827

文摘

Ligand-stabilized magnetic nanoparticles (NPs) with diameters of 4鈭? nm were spin-cast into monolayers on electron-transparent silicon nitride (SiN) substrates. SiN membranes facilitate detailed high-resolution characterization of the spin-cast monolayers by transmission electron microscopy (TEM) and approximate spin-casting onto wafers. Suspending the NPs in hexanes and pretreating the substrate with ultraviolet light and ozone (UVO) gives the best results. Computer-aided analysis of the arrays elucidates their grain structures, including identification of the grain boundaries and defects and measurements of the grain orientations and translational correlation lengths. Narrow NP size distributions result in close-packed arrays with minimal defects and large grains containing thousands of NPs. Edge dislocations, interstitials, vacancies, and overlapping NPs were observed. Deviations from close packing occur as the normalized standard deviation of the sample鈥檚 size distribution increases above approximately 11%. Polydisperse size distributions and deviations from spherical NP shapes frustrate assembly and prevent ordered packing.