An apparatus for the manufacture of synthetic diamonds includes a pressure vessel having a chamber therein, and a body located in the chamber. The pressure vessel and the body are formed of materials having different coefficients of expansion. The coefficient of expansion of the body is greater than the coefficient of expansion of the pressure vessel. The pressure vessel is formed from a material having a melting point in excess of 1327° C. and capable of withstanding a pressure of at least 4.4 Gpa at a temperature of at least 1327° C. The chamber is configured to receive the body, and a carbon source, the apparatus further comprising a heating means configured to heat at least the body to a temperature at least of 1327° C. The coefficient of expansion of the body is selected such that upon heating thereof to at least 1327° C. the pressure exerted on the carbon source is at least 4.4 Gpa.

A method for synthesizing a diamond by chemical vapor deposition, the method may include heating at least one internal space of at least one hot filament unit; wherein the at least one hot filament unit is positioned in a vacuum chamber; wherein a volume of each internal space out of the at least one internal space is smaller than one half of a volume of the vacuum chamber; feeding at least one gas to the at least one internal space; wherein the at least one gas comprises at least a carbon carrier gas; breaking the at least one gas by the at least one hot filament unit, to provide at least one radical; and depositing the at least one radical on an area of a substrate to provide the diamond.

A method for synthesizing a diamond by chemical vapor deposition, the method may include heating at least one internal space of at least one hot filament unit; wherein the at least one hot filament unit is positioned in a vacuum chamber; wherein a volume of each internal space out of the at least one internal space is smaller than one half of a volume of the vacuum chamber; feeding at least one gas to the at least one internal space; wherein the at least one gas comprises at least a carbon carrier gas; breaking the at least one gas by the at least one hot filament unit, to provide at least one radical; and depositing the at least one radical on an area of a substrate to provide the diamond.

This invention relates to a production method for non-detonation synthesis nanodiamond by exposing carbonaceous feedstock to a dense plasma focus. The nucleated nanodiamond particles have characteristics that differentiate them from known forms of nanodiamond. For instance, the nucleated nanodiamond particles are substantially spherical and have a substantially smooth surface, as may be demonstrated by TEM. The nucleated nanodiamond particles are also free of graphite and detonation carbon contaminants. The identity of the nanodiamond particles has been confirmed through raman spectra, for example. The nanodiamond particles have also been found to be effective as a lubricant composition when combined with a carrier oil.

This invention relates to a production method for non-detonation synthesis nanodiamond by exposing carbonaceous feedstock to a dense plasma focus. The nucleated nanodiamond particles have characteristics that differentiate them from known forms of nanodiamond. For instance, the nucleated nanodiamond particles are substantially spherical and have a substantially smooth surface, as may be demonstrated by TEM. The nucleated nanodiamond particles are also free of graphite and detonation carbon contaminants. The identity of the nanodiamond particles has been confirmed through raman spectra, for example. The nanodiamond particles have also been found to be effective as a lubricant composition when combined with a carrier oil.

A composite polycrystal includes: a polycrystalline diamond phase including a plurality of diamond particles; and non-diamond phases composed of non-diamond carbon. The non-diamond phases are distributed in the polycrystalline diamond phase. An average value of projected area equivalent circle diameters of the non-diamond phases is not more than 1000 nm.

A composite polycrystal includes: a polycrystalline diamond phase including a plurality of diamond particles; and non-diamond phases composed of non-diamond carbon. The non-diamond phases are distributed in the polycrystalline diamond phase. An average value of projected area equivalent circle diameters of the non-diamond phases is not more than 1000 nm.

A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and non-diamond carbon dispersed in the polycrystalline diamond, and has a concentration of contained hydrogen of less than or equal to 1000 ppm.

A single-crystal diamond material has a transmittance of light with a wavelength of greater than or equal to 410 nm and less than or equal to 750 nm of less than or equal to 15% for any wavelength, and is at least either of an electrical insulator according to optical evaluation and an electrical insulator according to electrical evaluation. A criterion of the optical evaluation can be a transmittance of light with a wavelength of 10.6 μm of greater than or equal to 1%. A criterion of the electrical evaluation can be an average resistivity of greater than or equal to 1×10.sup.6 Ωcm. Accordingly, a single-crystal diamond material having a low transmittance of light in the entire region of the visible light region and exhibiting a black color is provided.

A single-crystal diamond material has a transmittance of light with a wavelength of greater than or equal to 410 nm and less than or equal to 750 nm of less than or equal to 15% for any wavelength, and is at least either of an electrical insulator according to optical evaluation and an electrical insulator according to electrical evaluation. A criterion of the optical evaluation can be a transmittance of light with a wavelength of 10.6 μm of greater than or equal to 1%. A criterion of the electrical evaluation can be an average resistivity of greater than or equal to 1×10.sup.6 Ωcm. Accordingly, a single-crystal diamond material having a low transmittance of light in the entire region of the visible light region and exhibiting a black color is provided.