Amorphous Diamond as Thermionic Energy Converters

Amorphous diamond may be viewed to be sintered subnano (i.e. angstroms sized) diamond grains. In the following descriptions, amorphous diamond is portrayed as a micron thin coating material. However, in many cases, thicker coatings made by nanodia-mond impregnated metal matrix may also substitute amorphous diamond coating to achieve similar applications, such as for field emitters, or even as solar cells.

Amorphous diamond is essentially a chaotic carbon mixture with distorted sp2 and sp3 bonds. As such it possesses both metallic character of conductive graphite and semiconductor character of insulating diamond. Moreover, as each carbon atom is unique in its electronic state that is determined by the degree of distortion of its bonds, amorphous diamond contains numerous discrete potential energies for electrons. In fact, amorphous diamond may have the highest density of atoms (1.8 x 1023 per cubic centimeter) that is several times higher than ordinary materials (e.g. about four times of iron atoms or silicon atoms). Thus, amorphous diamond has the highest configuration entropy for both atoms and valence electrons.

Due to the distribution of discrete electronic energies with high density, amorphous diamond is uniquely capable of generating electricity and emit radiation. It has been demonstrated that amorphous diamond can be made as silicon free solar cells, front panel display field emission source, sensitive thermal sensing by IR detection, and perfect black body for energy conversion. Various

Diamond Nanotechnology: Synthesis and Applications by James C Sung & Jianping Lin

Copyright © 2009 by Pan Stanford Publishing Pte Ltd


amorphous diamond devices are being fabricated to exploit the superb properties of amorphous diamond.

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