The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

Ongoing advances in nanotechnology research have established a variety of methods to synthesize nanoparticles (NPs) from a diverse range of materials, including metals, semiconductors, ceramics, metal oxides, polymers, etc. Depending upon their origin and synthesis methods, NPs possess unique physicochemical, structural and morphological characteristics, which are important in a wide variety of applications concomitant to electronic, optoelectronic, optical, electrochemical, environment and biomedical fields. This review provides a comprehensive overview on various physical, chemical and bio-assisted methods largely employed to synthesize and fabricate NPs of varying size, surface characteristics, functionalities and physicochemical behavior. The key applications of nanoparticles have also been discussed.

Methods and strategies for the synthesis of diverse nanoparticles and their applications: a comprehensive overview

Cerium(IV) oxide ultrafine particles were prepared using a reaction within reversed micelles, which was known as a microemulsion method. The ultrafine particles, which were obtained by mixing the water-in-oil microemulsions containing cerium nitrate solution with those of ammonium hydroxide, were characterized by high-resolution electron microscope (HREM) observations. HREM micrographs revealed that nanometer-sized CeO2 particles were formed, and their shapes were uniform. Selected-area electron diffraction patterns of the particles were completely indexed as those of cerium(IV) oxide with the cubic fluorite structure, and the lattice constant calculated from radii of Debye−Sherrer rings was 0.541 nm. Most of the particles were distributed between 2 and 6 nm, and the mean particle size obtained in this method was between 2.6 and 4.1 nm. The size of 2.6 nm is the smallest among the values ever reported for CeO2 particles. Both direct and indirect optical energy gaps of the particles were independent of the...

M.P. Pileni

Papers

Nanometer metallic copper particle synthesis in reverse micelles