Nanomaterials: Manufacturing, Processing, and Applications

Authors

Srikanth Raghunathan Nanomat, Inc.

Publication Date

7/15/04

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Abstract

The particles with small size in the range from a few to several tens of nanometers are called quasi zero-dimensional mesoscopic system, quantum dots, quantized or Q-particles, etc. The reason that nanoscale materials and structures are so interesting is that size constraints often produce qualitatively new behavior. Nanotechnology arises from the exploitation of new properties, phenomena, processes, and functionalities that matter exhibits at intermediate sizes between isolated atoms or molecules (− 1 nm) and bulk materials (over 100 nm). As opposed to the microscale, the nanoscale is not just another step toward miniaturization, but is a qualitatively new scale. Hence quantum and size phenomena are allowed to manifest themselves either at a purely quantum level or in a certain admixture of quantum and classical components. At the foundation of nanosystems lie the quantum manifestations of matter that become relevant. Consequently, instead of being a limitation or an elusive frontier, quantum phenomena have become the crucial enabling tool for nanotechnology. Extensive research on semiconductor quantum dots has shown that these particles have properties halfway between macroscopic (bulk) and microscopic (molecular-like) substances and have recently aroused great interest in laser, photochemistry, and nonlinear optics. Bawendi et al. have observed a number of discrete electronic transitions and LO-phonon progression which were cleanly resolved for the first time in nanometer-scale cluster in CdSe. Jungnickel and Henneberger have described the luminescence properties of semiconductor nanocrystals and the carrier processes that are relevant for the light emission. Their study was concentrated on nanocrystal of size ≈ 5 nm, and hence observed strong carrier confinement. A size dependence in the luminescence efficiency of ZnS:Mn nanocrystals has also been observed by Bargava et. al. and stated that the Mn2 + ion d-electron states act as efficient luminescent centers while interacting with s–p electronic states of the host nanocrystals. They showed that this electronic interaction provides an effective energy transfer path and leads to high luminescent efficiencies at room temperature and hence suggested that nanocrystals doped with optically active luminescent centers may create new opportunities in the study and application of nanoscale material structures.

Because nanomaterials possess unique, beneficial chemical, physical, and mechanical properties, they can be used for a wide variety of applications. This review primarily focuses on the synthesis, properties, and applications of nanomaterials. It has been proven that the particles at the nanometer level have improved quality with respect to their potential application that include, but are not limited to, various structural, optical, electrical, mechanical, and catalytic activity, biomedical, next-generation computer chips, kinetic energy (KE) penetrators with enhanced lethality, better insulation materials, low-cost flat-panel displays, elimination of pollutants, tougher and harder cutting tools, high-sensitivity sensors, high-power magnets, future weapon platforms, aerospace, large lasting satellites, longer-lasting medical implants, corrosion resistance, etc.