Abstract: 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, hydrogen, oxygen, and the 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; hydrogen and oxygen 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.

Abstract: 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.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: 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.

Abstract: The present diamond single crystal is a diamond single crystal containing nitrogen atoms, in which a concentration of the nitrogen atoms changes periodically along a crystal orientation of the diamond single crystal, and an arithmetic average value Aave, a maximum value Amax, and a minimum value Amin of the distance of one period along the crystal orientation satisfy the relationship expressed by the following equation (I): (Amax)/1.25?(Aave)?(Amin)/0.75??(I).

Abstract: A cubic boron nitride polycrystal includes cubic boron nitride, the cubic boron nitride having an average grain size of not more than 150 nm, the cubic boron nitride polycrystal having a crack generation load of not less than 25 N in a breaking strength test in which an R200 ?m diamond indenter is used to apply a load at a rate of 100 N/min.

Abstract: 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, hydrogen, oxygen, and the 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; hydrogen and oxygen 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.

Abstract: A polycrystalline diamond body contains diamond particles, the diamond particles have a mean particle size of 50 nm or less, and a crack initiation load is 10 N or more as measured in a fracture strength test by pressing a diamond indenter D with a tip radius Dr of 50 ?m against a surface of the polycrystalline diamond body at a load rate F of 100 N/min. Accordingly, a polycrystalline diamond body that is tough and has a small diamond particle size, a cutting tool, a wear-resistant tool, a grinding tool, and a method for producing the polycrystalline diamond body are provided.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: The present diamond single crystal is a diamond single crystal containing nitrogen atoms, in which a concentration of the nitrogen atoms changes periodically along a crystal orientation of the diamond single crystal, and an arithmetic average value Aave, a maximum value Amax, and a minimum value Amin of the distance of one period along the crystal orientation satisfy the relationship expressed by the following equation (I): (Amax)/1.25?(Aave)?(Amin)/0.75??(I).

Abstract: A polycrystalline diamond body contains diamond particles, the diamond particles have a mean particle size of 50 nm or less, and a crack initiation load is 10 N or more as measured in a fracture strength test by pressing a diamond indenter D with a tip radius Dr of 50 ?m against a surface of the polycrystalline diamond body at a load rate F of 100 N/min. Accordingly, a polycrystalline diamond body that is tough and has a small diamond particle size, a cutting tool, a wear-resistant tool, a grinding tool, and a method for producing the polycrystalline diamond body are provided.

Abstract: A cubic boron nitride polycrystal includes cubic boron nitride, the cubic boron nitride having an average grain size of not more than 150 nm, the cubic boron nitride polycrystal having a crack generation load of not less than 25 N in a breaking strength test in which an R200 ?m diamond indenter is used to apply a load at a rate of 100 N/min.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: Nano polycrystalline diamond is composed of carbon and a plurality of impurities other than carbon. A concentration of each of the plurality of impurities is not higher than 0.01 mass %, and the nano polycrystalline diamond has a crystal grain size (a maximum length) not greater than 500 nm. The nano polycrystalline diamond can be fabricated by preparing graphite in which a concentration of an impurity is not higher than 0.01 mass % and converting graphite to diamond by applying an ultra-high pressure and a high temperature to graphite.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.

Abstract: Polycrystalline diamond having excellent resistance to crack propagation is provided. The polycrystalline diamond includes layered diamond and granular diamond. The layered diamond is formed by laminating plate-like diamond layers. When the polycrystalline diamond is observed in an arbitrary cross section, the layered diamond appearing at an observation visual field in the cross section occupies an area of more than or equal to 90% of the total area of the polycrystalline diamond in the observation visual field.

Abstract: Polycrystalline diamond includes cubic diamond and hexagonal diamond, and a ratio of X-ray diffraction peak intensity of a (100) plane of the hexagonal diamond to X-ray diffraction peak intensity for a (111) plane of cubic diamond is not lower than 0.01%. In addition, a present method of manufacturing polycrystalline diamond includes the steps of preparing a non-diamond carbon material having a degree of graphitization not higher than 0.58 and directly converting the non-diamond carbon material to cubic diamond and hexagonal diamond and sintering the non-diamond carbon material, without adding any of a sintering agent and a binder, under pressure and temperature conditions at which diamond is thermodynamically stable.

Abstract: Nano polycrystalline diamond is composed of carbon, an element of different type which is an element other than carbon and is added to be dispersed in carbon at an atomic level, and an inevitable impurity. The polycrystalline diamond has a crystal grain size not greater than 500 nm. The polycrystalline diamond can be fabricated by subjecting graphite in which the element of different type which is an element other than carbon has been added to be dispersed in carbon at an atomic level to heat treatment within high-pressure press equipment.