JP2992628B2 - Boron-carbon based superconducting material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron-carbon-based superconducting material. More specifically, the present invention relates to a boron-carbon-based superconducting material, which is expected to be used in various fields such as superconducting magnets, Josephson devices, and magnetic shields, and a superconductor using the same as a novel superconducting material Things.

[0002]

2. Description of the Related Art Conventionally, superconducting phenomena have been developed from strong electrolysis such as superconducting magnets and superconducting power storage to Josephson devices, S.M. Q. U. I. It is expected to be used in a wide range of fields, such as cryoelectronic element materials such as D and sheet materials for magnetic shielding.

[0003] Nb-Ti, Nb ₃
Metal-based superconductors such as Sn and V ₃ Ge have been used for applications using liquid He, and more recently, YBa.
₂ Cu ₃ O _{7+ δ,} energetically studied also towards its practical use for ceramic-based copper oxide high temperature superconductor such as _{Bi 2 Sr 2 CaCu 2 O 10} + 6 δ is underway. Under these circumstances, attention has been paid to boron, carbon, or boron-carbon compound-based materials as exhibiting superconducting properties.

[0004] However, the superconducting materials of boron carbide intermetallic compounds reported so far are not always satisfactory in superconducting properties, and in order to improve these properties, long annealing ( Heat treatment). In the case of the conventional boron-carbon carbide-based material, since it lacks thermodynamic stability, it is difficult to form a wire or a thin film, and it is extremely difficult to use the material for practical use.

[0005] In view of the above situation, the present invention opens up a new possibility of a boron-carbon-based superconductivity which is different from an alloy-based or oxide-based superconducting material and has a completely new composition. It is intended to provide a substance and a superconductor using the substance.

[0006]

In order to solve the above-mentioned problems, the present invention has a composition represented by the following formula: R ₃ M ₄ B ₄ C ₃ (where R is one or more of Y, Sc, and rare earth elements) And M
Represents one or more group VIII elements).

Further, according to the present invention, the composition formula is represented by the following formula: R ₃ M _4-x B _4-y C _3-z (R is one or more of Y, Sc, or a rare earth element;
Represents one or more group VIII elements, and 0 < x < 1,0
( Y < 1, 0 < z < 3, provided that x = y = 1 and z = 0 , but not).

Further, the present invention relates to the above-mentioned substance,
Is one or more of Ni, Pd, Pt, Rh, and Ir, the superconducting crystal structure is tetragonal or orthorhombic, and the lattice constant is a = 3.4 to 4.0 °. b = 3.4-4.0 ° c = 12.50-13.10 ° or 25.00-2
The present invention provides, as an embodiment, a structure containing 6.20%, a structure containing these substances, a superconductor as a molded body, and the like.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a novel superconducting material as described above, and more specifically, the rare earth element of R in the composition formula includes Y, Sc
, For example, La, Ce, Pr, Nd, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
u is indicated. M is, more specifically, Ni, P
d, Pt, Rh, Ir and the like are exemplified.

In each case, R and M may be one or more elements. The boron-carbon-based material of the present invention can be easily produced by a method such as an arc melt method under normal pressure. Because of its excellent thermodynamic stability, it can be easily applied as a practical material by forming a wire or a thin film. For this reason, power applications and device applications are expected. Another advantage of the substance of the present invention is that it is made of relatively inexpensive and easily available materials such as rare earth elements and transition metal elements.

Although it has been methodologically established to search for a new substance from a crystallographic point of view in a copper oxide high-temperature superconductor, the present invention is also applicable to the search for a substance of an intermetallic compound superconductor. Also tried to apply this method and succeeded in synthesizing a new substance, and it can be said that the development of an unknown functional substance has greatly advanced as a methodology. Hereinafter, examples will be shown, and embodiments of the present invention will be described in more detail.

[0012]

EXAMPLE A mass of Y and Ni metal and B and C powders were used as starting materials and weighed so as to have a compound ratio of Y ₃ Ni ₄ B ₄ C ₃ . 150 kg / cm using a press machine
^At a pressure of ² , a circular pellet having a diameter of 1 cm and a thickness of about 1 mm was obtained. These were put on a copper hearth and arc melted under an argon atmosphere.

From the obtained button-shaped sample, a width of about 1 mm,
A strip sample having a length of about 6 mm was cut out, and the temperature dependence of electric conduction was examined. Further, a part of the button-shaped sample was powdered, and the temperature dependence of the magnetic susceptibility was measured by SQUID, X-ray powder diffraction, and sample observation by an electron microscope were performed. FIG.
Shows the temperature dependence of electrical conduction. The superconducting transition temperature _Tc is about 11.5K. FIG. 2 shows the temperature dependence of the magnetic susceptibility. “Y ₁ Ni ₂ B ₂ C ₁ ” (T _c = about 16.5 K) known so far,
In addition to “Y ₁ Ni ₁ B ₁ C ₁ ” (T _c = about 3 K), 1
It can be seen that there is a phase showing complete diamagnetism at 1.5K. As can be seen from the X-ray powder diffraction shown in FIG. 3 from the volume percentage of the Meissner effect, it is considered that the main phase component “Y ₃ Ni ₄ B ₄ C ₃ ” shows superconductivity. The Meissner diamagnetism at 5K is 20% during Zero Field Cooling,
At the time of field cooling, it is about 12%.

The X-ray powder diffraction pattern shown in FIG.
It is shown that “Y ₁ Ni ₂ B ₂ C ₁ ”, “Y ₁ Ni ₁ B ₁ C ₁ ” and the like are included. FIG. 4 shows an image of a lattice image of an electron microscope, which is "Y ₁ Ni
_{2 B 2 C 1 ","} Y 1 " in addition to existing compounds of formula" Ni ₁ B ₁ C ₁ it can be seen that the new substance is present as represented by _{Y 3 Ni 4 B 4 C 3} ".

FIG. 5 shows Y which has been confirmed to exist.
₁Ni_TwoB_TwoC₁The crystal structure (a) of₁Ni₁B₁
C₁And the crystal structure (b) of the present invention_ThreeNi_FourB_FourC
_ThreeThis shows the crystal structure of And FIG.
FIG. 3 is a view of the structure (c) of the substance of the present invention viewed from the c-axis.
The Y of the present invention_ThreeNi_FourB_FourC_ThreeIs Y₁Ni_TwoB_Two
C₁1/2 unit cell and Y ₁Ni₁B₁C₁Laminated structure with
You can see that it is made.

Table 1 shows the crystal parameters (ideal positions) of Y ₃ Ni ₄ B ₄ C ₃ (z = 1) at room temperature in the space group P.
mm2 (NO. 25).

[0017]

[Table 1]

[0018]

According to the present invention, there is provided a novel superconductor having a composition completely different from that of a conventional boron carbide intermetallic compound superconductor. Since the substance of the present invention can be manufactured by a simple procedure of melting by an arc melt method,
This is a great advantage for molding processes such as wire forming.

[Brief description of the drawings]

FIG. 1 is a diagram showing the temperature dependence of electric conduction.

FIG. 2 is a diagram showing the temperature dependence of magnetic susceptibility.

FIG. 3 is an X-ray powder diffraction pattern diagram.

FIG. 4 is a photograph replacing a drawing showing an image of a lattice image of an electron microscope.

FIG. 5 is a crystal structure diagram of Y ₁ Ni ₂ B ₂ C ₁ , Y ₁ Ni ₁ B ₁ C ₁ and Y ₃ Ni ₄ B ₄ C ₃ .

6 is a view of Y ₃ Ni ₄ B ₄ C ₃ of FIG. 5 as viewed from the c-axis.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01B 13/00 565 H01L 39/12 ZAAC H01L 39/12 ZAA C04B 35/00 ZAAJ (72) Inventor Takehiko Matsumoto Sengen, Tsukuba, Ibaraki 1-2-1, Examiner, National Institute of Metals, National Science and Technology Agency Yuichi Fukakusa (56) References JP-A-7-291619 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) C04B 35/56 C01G 1/00 C04B 35/58 INSPEC (DIALOG)

Claims (6)

(57) [Claims] (1) a compound represented by the following formula: R ₃ M ₄ B ₄ C ₃ (R is one or more of Y, Sc, or a rare earth element;
Represents one or more group VIII elements). 2. The composition formula is as follows: R ₃ M _4-x B _4-y C _3-z (R is one or more of Y, Sc, or a rare earth element;
Represents one or more group VIII elements, and 0 < x < 1,0
< Y < 1, 0 < z < 3, provided that x = y = 1 and z = 0 , but not). 3. M is Ni, Pd, Pt, Rh or I
3. The superconducting material according to claim 1, which is at least one of r. 4. The substance according to claim 1, wherein the crystal structure is tetragonal or orthorhombic. 5. The lattice constant is as follows: a = 3.4 to 4.0 ° b = 3.4 to 4.0 ° c = 12.50 to 13.10 ° or 25.00 to 2
The superconducting material according to any one of claims 1 to 4, which is 6.20 °. 6. A superconductor comprising the substance according to claim 1.