Self-Assembly and Field-Responsive Optical Diffractions of Superparamagnetic Colloids

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• 作者：Jianping Ge ; Yongxing Hu ; Tierui Zhang ; Tuan Huynh ; Yadong Yin
• 刊名：Langmuir
• 出版年：2008
• 出版时间：April 1, 2008
• 年：2008
• 卷：24
• 期：7
• 页码：3671 - 3680
• 全文大小：1426K
• 年卷期：v.24,no.7(April 1, 2008)
• ISSN：1520-5827

文摘

Superparamagnetic Fe₃O₄ colloids with highly charged surfaces have been assembled into ordered structures inwater in response to external magnetic fields. The colloids form chainlike structures with regular interparticle spacingsof a few hundred nanometers along the direction of the external field so that the system strongly diffracts visible light.The balance between attractive (in this case, magnetic) and repulsive (electrostatic) forces dictates interparticle spacingand therefore optical properties. By changing the relative strength of these two forces, one can tune the peak diffractionwavelength over the entire visible spectrum. We were able to optimize the diffraction intensity and the tuning rangethrough studying their dependence on variables such as the size distribution and concentration of the Fe₃O₄ colloidsor ionic strength of the solutions. The fast, reversible response and the feasibility for miniaturization impart thesephotonic materials great potential in applications such as optoelectronic devices, sensors, and color displays.