Materials Functions in Nanometer Particles

纳米尺度的半导体和氧化物颗粒通过浮选、乳液或反胶束技术的溶液法合成。分析了它们的物理和化学性质，以用于特定的材料功能。不仅通过合成条件而且通过使用液相色谱法来控制尺寸。合成的Fe3O4小颗粒的直径在4至20 nm范围内。这些颗粒在溶液中与表面活性剂反应，通过浮选仅选择5nm的最小尺寸颗粒。它们的尺寸和形状足够均匀以在基板上形成二维的规则排列。在100 Oe下的磁性测量表明阻塞温度为15 K，这是由表面自旋无序产生的各向异性能解释的。光学测量结果表明，一个大的量子尺寸效应的蓝移到415 nm相比，700 nm的散装。吸收光谱与有效质量近似下的球形量子阱模型预测的结果吻合得很好。我们还制备了CeO_2和ZnO等样品，并根据它们的尺寸和形状分析了它们的各种光化学效应，如光催化反应。

Nanometer-scale semiconductor and oxide particles are synthesized by solution methods with flotation, emulsion, or reverse micelle technique. Their physical and chemical properties are analyzed for specific materials functions. Sizes are controlled not only by synthesis conditions but also by making use of liquid chromatography.Small particles of Fe304 are synthesized in their diameter ranging from 4 to 20 nm. These particles are reacted with surfactants in solution and only smallest size particles of 5 nm are selected by flotation. Their size and shape are sufficiently uniform to form regular arrangement in two-dimension on a substrate. Magnetic measurements at 100 Oe show the blocking temperature of 15 K explained by the anisotropy energy coming form surface spin disorder around the surface.Small particles of CdSe of size as small as 1.3 nm are produced by reverse micelle technique. Optical measurements show a large quantum-size effect of blue shift to 415 nm as compared with 700 nm of the bulk. Absorption spectra are in good agreement with prediction by the spherical quantum well model with effective mass approximation.Other samples such as CeO2 and ZnO are also produced and their various photochemical effects such as photo-catalytic reactions are analyzed in terms of their size and shape.