JP3921537B2 - Method for producing single-walled boron nitride nanotubes by laser ablation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a method for producing single-walled boron nitride nanotubes. More specifically, the invention of this application relates to boron nitride single-walled nanotubes, which are expected as materials having unprecedented properties in the fields of semiconductor materials, emitter materials, heat-resistant filling materials, high-strength materials, catalysts, etc., with high purity. The present invention relates to a method for producing single-walled boron nitride nanotubes that can be produced.
[0002]
[Prior art]
A carbon nanotube, a nanometer-sized tubular carbon material in which carbon atoms are arranged in a cylindrical shape, is known. These carbon nanotubes are synthesized by an arc discharge method, a laser heating method, a chemical vapor deposition method, or the like, and exhibit the properties of a conductor or a semiconductor depending on the diameter, winding method, number of layers, and the like.
[0003]
In recent years, since boron nitride has structural similarity with graphite, boron nitride nanotubes have also been synthesized by the same method as described above. In addition, as for the method for producing boron nitride nanotubes, nickel boride is used as a catalyst, borazine is used as a raw material (see, for example, Non-Patent Document 1), carbon is used as a template, boron oxide and nitrogen are used. A method of synthesizing by reacting in a high-frequency induction heating furnace (for example, see Patent Documents 1 and 2) has been proposed. Boron nitride nanotubes have the great advantage of being thermally and chemically stable compared to carbon nanotubes. For this reason, boron nitride is expected as a material having unprecedented characteristics in the fields of semiconductor materials, emitter materials, heat-resistant filling materials, high-strength materials, catalysts, and the like.
[0004]
[Non-Patent Document 1]
ORLourie et al., Chemical Materials (Chem. Mater.), 2000, Vol. 12, p. 1808
[Patent Document 1]
JP 2000-109306 A [Patent Document 2]
Japanese Patent Laid-Open No. 2002-97004
[Problems to be solved by the invention]
However, the above-described method for producing boron nitride nanotubes has problems such as safety and inclusion of impurities such as carbon, and it is difficult to measure physical properties such as semiconductor properties and strength of boron nitride nanotubes. Met.
[0006]
The invention of this application was made in view of such circumstances, and provides a method for producing single-walled boron nitride nanotubes that can produce high-purity single-walled boron nitride nanotubes that do not contain impurities such as carbon. It is a problem to be solved.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention of this application has a wavelength of 1.064 μm, a pulse width of 60 ps, a repetition rate of 2 × 10 ⁵ pulses / second, and an intensity of 2.7 × 10 ¹¹ W / cm ^{2 in} a nitrogen atmosphere of 100 Torr. Provided is a method for producing single-walled boron nitride nanotubes, which comprises irradiating boron nitride as a target with a laser beam (claim 1).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing single-walled boron nitride nanotubes of the invention of this application, a boron laser as a target is irradiated with a pulse laser of a short time-ultra high repetition number under a reduced pressure of nitrogen, so that the laser light is made close to the focal point of the laser light. The product is deposited. Among these products are high purity single-walled boron nitride nanotubes with very few impurities.
[0009]
The single-walled boron nitride nanotubes can be obtained by a short-time and ultra-high repetition number of laser irradiation methods, which is an epoch-making that is not found in the prior art.
[0010]
Hereinafter, an Example is shown and the manufacturing method of the single layer boron nitride nanotube of invention of this application is demonstrated in more detail.
[0011]
【Example】
Using a laser with a wavelength of 1.064 μm, a pulse width of 60 ps, a repetition rate of 2 × 10 ⁵ pulses / second, and a laser intensity of 2.7 × 10 ¹¹ W / cm ^{2 in} a vacuum of 100 Torr, a laser with a very high repetition rate Irradiated to boron nitride. Soot-like product was deposited near the focal point of the laser beam. As a result of measurement using a mass spectrometer, the product had a high purity with a total amount of impurities of 220 ppm or less. This product was dispersed in carbon tetrachloride, subjected to ultrasonic treatment, and dropped onto a copper grid with a carbon film to prepare a sample for observation with a transmission electron microscope.
[0012]
FIG. 1 is a photograph of an image observed using a high-resolution transmission electron microscope.
[0013]
Single-walled nanotubes were confirmed. The tube was wound in a zigzag shape.
[0014]
FIG. 2 is a diagram showing an electron energy loss spectrum of the obtained single-walled nanotube.
[0015]
In FIG. 2, peaks of boron and nitrogen appear at 188 eV and 401 ev, respectively, and the B / N ratio is 0.9 ± 0.2. From this, it was confirmed that stoichiometric boron nitride was generated. In addition, in FIG. 2, there are no peaks other than boron and nitrogen, and it was confirmed that the single-walled boron nitride nanotube as a product has high purity.
[0016]
【The invention's effect】
As described above in detail, according to the invention of this application, high-purity single-walled boron nitride nanotubes that do not contain impurities such as carbon are produced.
[Brief description of the drawings]
FIG. 1 is a photograph of a high-resolution transmission electron microscope image of single-walled boron nitride nanotubes.
FIG. 2 is a diagram showing an electron energy loss spectrum of single-walled boron nitride nanotubes.

Claims (1)

It is characterized by irradiating boron nitride as a target with laser light of wavelength 1.064μm, pulse width 60ps, repetition rate 2 × 10 ⁵ pulses / second, intensity 2.7 × 10 ¹¹ W / cm ² in 100Torr nitrogen atmosphere A method for producing single-walled boron nitride nanotubes.

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