The application discloses a preparation method of monocrystal uranium dioxide nuclear fuel pellets, comprising: granulating and pelleting UO.sub.2 powder to obtain UO.sub.2 pellets; then coating surfaces of the UO.sub.2 pellets with monocrystal growth additive micro powder to form core-shell structure particles; and activated-sintering the core-shell structure particles at high temperature, liquefying the monocrystal growth additive on the surface of the core-shell structure particle at high temperature and then diffusing into UO.sub.2 pellets, dissolving the UO.sub.3 in the liquid monocrystal growth additive, and recrystallizing the UO.sub.2 to form the monocrystal UO.sub.2 nuclear fuel pellets.

The present invention provides polycrystalline silicon suitably used as a raw material for producing single crystal silicon. The polycrystalline silicon rod of the present invention is a polycrystalline silicon rod grown by chemical vapor deposition performed under a pressure of 0.3 MPaG or more, wherein when a plate-shaped sample piece collected from an arbitrary portion of the polycrystalline silicon rod is observed with a microscope with a temperature increased from a temperature lower than a melting point of silicon up to a temperature exceeding the melting point of silicon, a heterogeneous crystal region, which is a crystal region including a plurality of crystal grains heterogeneously assembled and including no needle-like crystal, having a diameter exceeding 10 ?m is not observed.

The present invention provides polycrystalline silicon suitably used as a raw material for producing single crystal silicon. The polycrystalline silicon rod of the present invention is a polycrystalline silicon rod grown by chemical vapor deposition performed under a pressure of 0.3 MPaG or more, wherein when a plate-shaped sample piece collected from an arbitrary portion of the polycrystalline silicon rod is observed with a microscope with a temperature increased from a temperature lower than a melting point of silicon up to a temperature exceeding the melting point of silicon, a heterogeneous crystal region, which is a crystal region including a plurality of crystal grains heterogeneously assembled and including no needle-like crystal, having a diameter exceeding 10 ?m is not observed.

The disclosure relates to a device for continuously producing qualitatively high-grade crystalline silicon carbide, in particular in the form of nanocrystalline fiber.

The disclosure relates to a device for continuously producing qualitatively high-grade crystalline silicon carbide, in particular in the form of nanocrystalline fiber.

There is provided a method of manufacturing a semiconductor device. The method includes: forming a first amorphous silicon film on a substrate in a process chamber; and etching a portion of the first amorphous silicon film using a hydrogen chloride gas under a temperature at which an amorphous state of the first amorphous silicon film is maintained, in the process chamber.

The present disclosure provides a local carbon-supply device and a method for preparing a wafer-level graphene single crystal by local carbon supply. The method includes: providing the local carbon-supply device; preparing a nickel-copper alloy substrate, placing the nickel-copper alloy substrate in the local carbon-supply device; placing the local carbon-supply device provided with the nickel-copper alloy substrate in a chamber of a chemical vapor-phase deposition system, and introducing a gaseous carbon source into the local carbon-supply device to grow the graphene single crystal on the nickel-copper alloy substrate. A graphene prepared by embodiments of the present disclosure has the advantages of good crystallinity of a crystal domain, simple preparation condition, low cost, a wider window of condition parameters required for growth, and good repeatability, which lays a foundation for wide application of the wafer-level graphene single crystal in a graphene apparatus and other fields.

The crystal plane in the interior of the diamond substrate has a curvature higher than 0 km.sup.1 and equal to or lower than 1500 km.sup.1 by preparing a base substrate, forming a plurality of pillar-shaped diamonds formed of diamond single crystals on one side of the base substrate, causing diamond single crystals to grow from tips of each pillar-shaped diamond, coalescing each of the diamond single crystals grown from the tips of each pillar-shaped diamond to form a diamond substrate layer, separating the diamond substrate layer from the base substrate, and manufacturing the diamond substrate from the diamond substrate layer.

A composition of matter comprising a plurality of nanowires on a substrate, said nanowires having been grown epitaxially on said substrate in the presence of a metal catalyst such that a catalyst deposit is located at the top of at least some of said nanowires, wherein said nanowires comprise at least one group III-V compound or at least one group II-VI compound or comprises at least one non carbon group IV element; and wherein a graphitic layer is in contact with at least some of the catalyst deposits on top of said nanowires.

Methods for producing nanostructures from copper-based catalysts on porous substrates, particularly silicon nanowires on carbon-based substrates for use as battery active materials, are provided. Related compositions are also described. In addition, novel methods for production of copper-based catalyst particles are provided. Methods for producing nanostructures from catalyst particles that comprise a gold shell and a core that does not include gold are also provided.