Showing papers by "Hidefumi Hiura published in 1995"

Process for purifying, uncapping and chemically modifying carbon nanotubes

Abstract: Disclosed is a process for purifying carbon nanotubes which has steps of 1) mixing carbon nanotubes which accompany carbon impurities with a reagent selected from a group consisting of oxidation agents, nitration agents and sulfonation agents in liquid phase, 2) reacting the carbon nanotubes with the reagent at a predetermined temperature in the liquid phase, wherein the carbon impurities except carbon nanotubes are selectively reacted to dissolve in the liquid phase, and 3) separating carbon nanotubes from which the impurities were released from the liquid phase then washing and drying it. A process for uncapping carbon nanotubes and a process for chemically modifying carbon nanotubes are also disclosed.

Origins of fullerenes in rocks.

Abstract: This article is a technical comment and author response to the the discovery of naturally occuring fullerenes in Shunga rock samples. The commenting researchers did not find detectable amounts of fullerenes in a variety of carbon-rich rocks. They hypothesize that the fullerenes found in the Shunga sample were probably a localized event. The original researchers, Buseck and Tsipursky, provide a rebuttal with further comments including parallels to other minerological occurences. All agreed that more data are needed. 10 refs.

Metal-coated carbon nanotube and its production

Abstract: PURPOSE: To produce carbon nanotube whose surface is coated with a metal. CONSTITUTION: An ion containing a metal is deposited as a metal or a metal salt utilizing a chemical reaction such as an ion exchange reaction, an oxygenphilic reaction or a reduction reaction under mild conditions in a liquid phase to coat a nanotube with a metal. The nanotube coated with the metal is considered to be applied to an electronic device as a pseudomonodimentional electric conductor and a nanotube coated with a ferromagnetic metal can be utilized as a magnetic material having high performance. The nanotube can be utilized also as a solid catalyst. COPYRIGHT: (C)1996,JPO

Method of producing carbon material by bending at least one carbon atom layer of graphite

Abstract: A novel carbon material is obtained by bending at least one carbon atom layer of graphite in at least one selected region along either, or both, of lines I and II in FIG. 1. The bending can be accomplished by scanningly picking the carbon atom layer(s) with a probe of an atomic force microscope or another scanning microscope. The obtained carbon material has at least one round bend having a width of 0.1-10 nm and at least one flap region having a triangular, rectangular or still differently polygonal shape in plan view. When the carbon atom layer(s) is bent with very small radii of curvature, a finely striped ridge-and-groove structure appears in the round bend. The physical properties of the obtained carbon material are uniquely determined by the direction(s) of bending, width of each bend, shape and size of each flap region and the stripe pitch of the ridge-and-groove structure.

Ion-exchanged carbon nanotube, its production, buffering medium comprising the same and element capturing and collecting method using the same

Abstract: PURPOSE: To verify and enhance the functionality of carbon nanotubes by providing the nanotubes with a buffering function capable of freely controlling the pH of a liquid over the range from an acidic value to an alkaline value, a function as an ion exchange medium, that is effected by substituting protons in the surfaces of the nanotubes with various other cations, and further, a function of capturing, collecting and recovering rare elements such as uranium(U). CONSTITUTION: In this production of the carbon nanotubes, protons (H + ) of carboxyl groups (-COOH) used as surface functional groups of carbon nanotubes are substituted with other cations by utilizing ion exchange reaction. At this time, e.g. by substituting the protons with strongly basic Na + ions, alkaline nanotubes can be produced, and also, by combining the alkaline nanotubes with unsubstituted acidic nanotubes, the resultant combination can be utilized as a medium provided with a buffering function. Further, the nanotubes can also be utilized as a medium for capturing, collecting and recovering a rare element(s) such as uranium(U) by fixing cations contg. the rare element(s) on the nanotubes. COPYRIGHT: (C)1996,JPO