Provided is polycrystalline diamond having a diamond single phase as basic composition, in which the polycrystalline diamond includes a plurality of crystal grains and contains boron, at least either of nitrogen and silicon, and a remainder including carbon and trace impurities; the boron is dispersed in the crystal grains at an atomic level, and greater than or equal to 90 atomic % of the boron is present in an isolated substitutional type; the nitrogen and the silicon are present in an isolated substitutional type or an interstitial type in the crystal grains; each of the crystal grains has a grain size of less than or equal to 500 nm; and the polycrystalline diamond has a surface covered with a protective film.

A product of a chemical reaction, being a five carbon atom molecule having a tetrahedral structure consisting of four apical carbon atoms and a fifth carbon atom located centrally within the tetrahedral structure.

Single-crystal diamond is composed of carbon in which a concentration of a carbon isotope .sup.12C is not lower than 99.9 mass % and a plurality of inevitable impurities other than carbon. The inevitable impurities include nitrogen, boron, hydrogen, and nickel, and a total content of nitrogen, boron, and hydrogen of the plurality of inevitable impurities is not higher than 0.01 mass %. In order to manufacture single-crystal diamond, initially, a hydrocarbon gas in which a concentration of the carbon isotope .sup.12C is not lower than 99.9 mass % is subjected to denitrification.

Disclosed herein is an apparatus and method for growing a diamond. The apparatus for growing a diamond comprises: a reaction cell that is configured to grow the diamond therein; a main heater including a main heating surface that is arranged along a first inner surface of the reaction cell; and a sub-heater including a sub-heating surface that is arranged along a second inner surface of the reaction cell, the second inner surface being non-parallel with the first inner surface.

The invention relates to a multi-chamber with ultra-high-pressure or hydraulic motor compressors or motor pumps for compressing gas or liquid at ultra-high pressure, formed by several different-sized concentric chambers, wherein each chamber contains smaller chambers, there being installed between the chambers motors or pumps that enable fluid to be introduced into the inner chambers at increasingly greater pressure.

An electrode comprising synthetic high-pressure high-temperature diamond material, the diamond material comprising a substitutional boron concentration of between 1×10.sup.20 and 5×10.sup.21 atoms/cm.sup.3 and a nitrogen concentration of no more than 10.sup.19 atoms/cm.sup.3. The electrode has a ΔE.sub.3/4-1/4 as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO.sub.3 and 1 mM of Ru(NH.sub.3).sub.6.sup.3+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV, and/or a peak to peak separation ΔE.sub.p as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO.sub.3 and 1 mM of Ru(NH.sub.3).sub.6.sup.3+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV.

An electrode comprising synthetic high-pressure high-temperature diamond material, the diamond material comprising a substitutional boron concentration of between 1×10.sup.20 and 5×10.sup.21 atoms/cm.sup.3 and a nitrogen concentration of no more than 10.sup.19 atoms/cm.sup.3. The electrode has a ΔE.sub.3/4-1/4 as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO.sub.3 and 1 mM of Ru(NH.sub.3).sub.6.sup.3+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV, and/or a peak to peak separation ΔE.sub.p as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO.sub.3 and 1 mM of Ru(NH.sub.3).sub.6.sup.3+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV.

In an embodiment, a polycrystalline diamond table includes a plurality of bonded diamond grains and a plurality of interstitial regions defined by the plurality of bonded diamond grains. The polycrystalline diamond table may be at least partially leached such that at least a portion of at least one interstitial constituent has been removed from at least a portion of the plurality of interstitial regions by exposure to a leaching agent. The leaching agent may include a mixture having a ratio of weight % hydrofluoric acid to weight % nitric acid of about 1.0 to about 2.4, and water in a concentration of about 50 weight % to about 85 weight %. Various other materials, articles, and methods are also disclosed.

A method of forming a polycrystalline diamond body includes mixing a sintering agent with diamond powder to form a premixed layer, the sintering agent including at least one alkaline earth metal carbonate; forming an infiltration layer adjacent to the premixed layer, the infiltration layer including an infiltrant material including at least one alkaline earth metal carbonate; and subjecting the premixed layer and the infiltration layer to high pressure high temperature conditions.

A method of forming a polycrystalline diamond body includes mixing a sintering agent with diamond powder to form a premixed layer, the sintering agent including at least one alkaline earth metal carbonate; forming an infiltration layer adjacent to the premixed layer, the infiltration layer including an infiltrant material including at least one alkaline earth metal carbonate; and subjecting the premixed layer and the infiltration layer to high pressure high temperature conditions.