Abstract: According to the present invention, milled carbon fiber is mixed with a boron compound and graphitized in the presence of nitrogen, and thereafter subjected to modifying treatment by applying impact selectively to fiber edge parts of the carbon fiber.

Abstract: There are disclosed graphite materials for a negative electrode used in a lithium secondary battery which graphite materials have an average specific surface area of 1.5 m2/gram to 5 m2/gram and comprise (A) milled graphite fibers which are produced by milling and graphitizing mesophase pitch-based carbon fibers, and which have an interplanar spacing of the graphite layer (d002) of at most 0.337 nm and a specific surface area of 0.8 m2/gram to 1.3 m2/gram; and (B) graphite materials which have an interplanar spacing of the graphite layer (d002) of at most 0.336 nm, a degree of graphitization (P101/P100) of at least 2.0 and a specific surface area of 2 m2/gram to 15 m2/gram, wherein the components (A) and (B) are mixed at a ratio (A)/(B) by weight of 90/10 to 50/50.

Abstract: Disclosed is a process for preparing milled graphite fibers in which the amount of metallic components contained in the milled carbon fibers before graphitizing is limited to not more than 100/1,000,000 in terms of a ratio by weight. Also disclosed is a process for preparing milled graphite fibers in which the amount of metallic components contained in the milled carbon fibers before graphitizing except metallic components originally contained in the fibers themselves is limited to not more than 50/1,000,000 in terms of a ratio by weight. According to these processes, there can be obtained milled graphite fibers whose surfaces are inert, which suffer few longitudinal crackings and which are almost free from occurrence of particulate substances comprising agglomerated or bonded fibers.

Abstract: A negative electrode for use in a secondary battery which comprises milled graphite fibers derived from mesophase pitch each having circumferential, upper end and lower end faces, the milled graphite fibers each being composed of graphite layers having therebetween voids as inlets and outlets for lithium ions, all of the circumferential, upper end and lower end faces having openings of the voids between the graphite layers, which serve as inlets or outlets for lithium ions. This negative electrode for use in a secondary battery can be utilized to provide a lithium secondary battery of nonaqueous electrolyte which has large charge and discharge capacities and which permits setting the current density at charge or discharge high.

Abstract: A carbon material for use in a lithium secondary battery, which is obtained by graphitization conducted in the presence of a boric compound so as to contain boron in an amount ranging from 1,000 ppm to 30,000 ppm and which, when subjected to X-ray diffractometry, exhibits an interplanar spacing of 002 surface (d.sub.002) of not greater than 0.338 nm, a crystallite size along c-axis (Lc) of at least 35 nm, a crystallite size along a-axis (La) of at least 50 nm and a ratio of diffraction peak (101) to diffraction peak (100), designated as P.sub.101 /P.sub.100, of at least 1.0; a negative electrode and a lithium secondary battery each produced by using the above carbon material; and a process for producing the carbon material. This carbon material exhibits large charge and discharge capacities, so that it can provide a negative electrode for use in a lithium secondary battery which is excellent in charge and discharge cycle characteristics.

Abstract: A negative electrode for use in a secondary battery is disclosed, comprising milled carbon fibers derived from mesophase pitch wherein the milled carbon fibers each has a fiber cut surface and a fiber axis intersecting with each other at cross angles, the smaller one thereof being at least 65.degree. on the average. This negative electrode does not suffer from property deterioration, irrespective of multiple repetitions of charge and discharge, from which a nonaqueous-electrolyte-loaded lithic secondary battery having excellent cycle characteristics can be fabricated.

Abstract: A process for producing an optically isotropic reformed pitch useful for various carbon materials is provided. This process comprises mixing a pitch having a ratio of aromatic hydrocarbon fa of more than 0.6 with a strong Lewis acid and a co-solvent so as to give a mol ratio of the said Lewis acid to the said pitch in the range of 0.3.about.5.0 and a mol ratio of the said co-solvent to the said pitch in the range of ratio of 2.5.about.50, reacting the mixture at a temperature of 100.degree..about.300.degree. C. and removing the Lewis acid and the co-solvent from the reaction product. Meso-Carbon microbeads having a uniform diameter of 20 .mu.m or less can be produced at a high yield of 60% or more by heat treating the said reformed pitch at 200.degree..about.380.degree. C. to produce the optically anisotropic small spheres and separating them from an optically isotropic matrix.

Abstract: An optically isotropic pitch can be obtained by a two-stage heat-treatment which combines a heat treatment with air-blowing under normal pressure with a heat treatment with air-blowing under a reduced pressure. Such a pitch is suitable for using as a raw material for producing carbon fibers or activated fibers.

Abstract: A process for providing activated carbon fibers consisting of optically anisotropic components and optically isotropic components by spinning a pitch into fibers, and infusibilizing the resulting fibers, followed by an activation treatment. The pitch for spinning is prepared by melt mixing together (A) 100 parts by weight of an optically isotropic pitch having a softening point of 230.degree.-300.degree. C. obtained by heat treatment of a pitch while blowing an oxygen containing gas into the pitch, and (B) 10-50 parts by weight of an optically isotropic pitch having a softening point of 200.degree.-270.degree. C. obtained by polymerization of naphthalene in the presence of a Lewis acid catalyst. The optically isotropic pitch (B) is further characterized as having the property of being converted into an optically anisotropic pitch by the stress occurring at the time of spinning.

Abstract: A dry etching apparatus has a vacuum chamber provided therein with an RF electrode. On the RF electrode an object substrate(s) is placed. The RF electrode is covered with a substrate bed(s) and detachable dielectric members. The substrate bed(s) includes a dielectric portion and a conductive portion provided just under the dielectric portion. The conductive portion is equipotential in terms of direct current to the RF electrode. At least one gap extension is consituted of a gap(s) between the dielectric members, a gap(s) between the dielectric members and the substrate bed(s), etc. and extends from the surface of the RF electrode to the plasma space. The gap extension(s) extends zigzaggedly from the RF electrode to the plasma space so that the plasma space can not structurally be viewed from the surface of the RF electrode irrespective the dimesions of the substrate.