KR100928553B1 - SUPERCONDUCTING COMPOSITIONS WITH HIGH Tc AND PROCESSES FOR PREPARING BULK MATERIALS COMPRISED OF THE SAME - Google Patents

Abstract

The present invention is a superconductor composition represented by the formula Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _Z or Tl _1-x M _x A ₂ Ca _{3-u Du} Cu ₄ O _z The present invention relates to a superconductor powder and a superconductor bulk, and to a method for producing the superconductor bulk, wherein the superconductor composition includes an oxide containing A-Ca-Cu, an oxide containing AD-Ca-Cu, and MA-Ca-Cu. Tl-MA-Ca-Cu-O or Tl-MAD by mixing an oxide containing Tl and an oxide containing M with a precursor powder made of one or more materials selected from oxides containing oxides and MAD-Ca-Cu The superconducting precursor powder of -Ca-Cu-O composition can be synthesized by a predetermined heat treatment at normal pressure, and exhibits stable superconductivity critical temperature characteristics of about 100 K or more, thereby enabling economical synthesis according to the present invention. Oxidation with a layer structure on Tl-1234, where application is expected System there is the effect obtained with high temperature superconductor compositions and the like.

Oxide High Temperature Superconductor, Tl-1234 Phase, Ba Substitution, Element Substitution

Description

Superconducting COMPOSITIONS WITH HIGH Tc AND PROCESSES FOR PREPARING BULK MATERIALS COMPRISED OF THE SAME

The present invention relates to a high temperature superconductor composition (particularly, a high temperature superconductor composition having a Tl-1234 phase structure), a superconductor powder and superconductor bulk consisting thereof, and a method for producing the superconductor bulk thereof.

The superconductor is a material in which the electrical resistance disappears when cooled below the intrinsic superconductivity critical temperature (T _c ) and the diamagnetic magnetism effect is observed. The higher the critical temperature, the more economically the superconductivity can be utilized.

Therefore, the development of superconductors is focused on increasing the critical temperature. Since 1987, various types of superconductors having a critical temperature of 77 K or more, which is the boiling point of liquid nitrogen, have been developed. -Cu-O), bismuth-based (Bi-Sr-Ca-Cu-O), thallium-based (Tl-Ba-Ca-Cu-O, Tl-Sr-Ca-Cu-O), mercury-based (Hg- Ba-Ca-Cu-O) and the like are known.

In general, the superconductor can maximize its characteristics at a temperature below about 3/4 of the critical temperature. Therefore, when using liquid nitrogen as the refrigerant, a superconductor having a superconductivity critical temperature of about 100 K or more is preferable.

It is known that thallium (Tl) based superconductors have various superconducting phases depending on the number of Tl-O layers and the number of Cu-O layers in the unit cell structure.

That is, in the case of the Tl-Ba-Ca-Cu-O system, TlBa ₂ Ca _{n -1} Cu _n O _z (n = 1 to 5), which is one layer of Tl-O, and Tl ₂ Ba _{2, which} has two layers of Tl-O, The composition of Ca _{n -1} Cu _n O _z (n = 1-4) is known, and these compositions are abbreviated for Tl (Ba) -12 (n-1) n phase and Tl (Ba) -22 (n-1), respectively. n), where n represents the number of Cu—O layers.

On the other hand, in the case of Tl-Sr-Ca-Cu-O system, the composition of TlSr ₂ Ca _{n -1} Cu _n O _z (n = 1 to 3) is known.

The unit cell structure of the Tl system is, for example, in the case of Tl ₂ Ba ₂ Ca _{n -1} Cu _n O _z , two Tl-O layers and a perovskite type Ba ₂ Ca _{n -1} Cu _n O _z layer alternately c. It has a structure arranged in the axial direction, the Cu-O layer has a structure stacked in the c-axis direction again inside the Ba ₂ Ca _{n -1} Cu _n O _z layer.

Among these thallium-based superconductor phases, superconductors having n = 3 and n = 4 are evaluated to have excellent critical temperature and critical current density characteristics, and a superconductor having one Tl-O layer is a Tl-O layer. It is known to exhibit superior physical properties than these two superconductors [M. Jergel, A. Conde Gallardo, C. Falcony Guajardo and V. Strbik, "TOPICAL REVIEW; Tl-based superconductors for high-current, high-field applications" Supercond. Sci. Technol. 9, 427-446 (1996).

Therefore, the synthesis of superconductors of Tl-1223 phase or Tl-1234 phase composition is of great technical importance.

However, a superconductor having a composition of one Tl-O layer is not easier to synthesize a single phase compared to a superconductor having a composition of two Tl-O layers. Particularly in the case of Tl (Ba) -1223 phase and Tl (Ba) -1234 phase, the Tl-O double layer structure is more than the Tl-O single layer when the carbon content in the precursor used in the preparation of the specimen is very large. Materials are synthesized, and the synthesis should be done by minimizing the carbon content of the precursor material for single phase synthesis, and a device capable of applying a high pressure of about 3.5 GPa (about 35000 atm) even with a low carbon content precursor material. It is known that only a single phase can be synthesized [A. Iyo, Y. Aizawa, Y. Tanaka, M. Tokumoto, K. Tokiwa, T. Watanabe and H. Ihara, "High-Pressure synthesis of TlBa ₂ Ca _{n -1} Cu _n O _y (n = 3 and 4) with T _c = 133.5 K (n = 3) and 127 K (n = 4) "Physica C 357-360, 324-328 (2001)].

In comparison, Tl (Sr) -1234 specimen synthesis of the structure is still watching the bar virtually no for a single-phase synthesis _{(Tl 0 .5 Pb 0 .5)} Sr 1 .6 Ba 0 .4 Ca 3 Cu 4 O y Attempts have been made to synthesize specimens of phase 1234 as a composition, but it has been reported that no single phase of phase 1234 was synthesized [Nasser M. Hamdan, “The role of charge carrier concentration in Tl-1234" Physica B 284-288, 1093-. 1094 (2000).

In addition, the 1234 phase composition of _{(Tl 0 .64 Pb 0 .2 Bi} 0 .16) Sr 2 Ca 3 Cu 4 O _z composition when the composite specimen with a rather search Tl-1223 superconducting phase composition is very well-known synthesis of T, Kaneko, T. Wada, H. Yamauchi and S. Tanaka, “(Tl, Pb, Bi) Sr ₂ Ca ₂ Cu ₃ O _z superconductors with zero resistance at 120 K” Appl. Phys. Lett. 56, 1281-1283 (1990).

In addition to the thallium (Tl) -based superconductor, the superconductor of 1234 phase composition is carbon-based (C-1234), boron-based (B-1234), gallium-based (Ga-1234), aluminum-based (Al-1234), copper-based (Cu -1234) and the like (E. Takayama-Muromachi, ATMateev, M. Isobe, T. Kawashine and Y. Matsui, "High-pressure syntheses of series of high T _c -superconductors (Cu, X) Sr ₂ Ca _{n -1} Cu _n O _y (X = Ge, P, C, S) "Physica C 282-287,949-950 (1997)], all synthesized at high pressures of several GPa and at high temperatures above about 1100 ° C. It is known that the superconductor of is not synthesized. In addition, most of these 1234 phase superconductors are known to have a high critical temperature.

Accordingly, the inventors of the present invention expect that if a single phase of 1234 phase composition is synthesized under a normal pressure, mass production and the like will be easy and relatively economical will be ensured, and superconducting critical temperature characteristics above the liquid nitrogen temperature will be expected. Expected to be efficient use and application, extensive efforts and efforts to synthesize a superconductor having a 1234 phase composition under the normal heat treatment conditions, Tl-based phase 1234 phase almost single phase through a suitable composition and synthesis method Superconductor synthesis is possible and the critical temperature is also confirmed that the 100 K or more completed the present invention.

Accordingly, an object of the present invention is to provide a high-temperature superconductor composition having a critical temperature of about 100 K or more, a superconductor powder and superconductor bulk made of the composition, and a method for producing the superconductor bulk at atmospheric pressure, respectively.

In order to achieve the above object, the superconductor composition according to the present invention is formula Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _z or Tl _1-x M _x A ₂ Ca _3-u D _u Cu ₄ In O _z , M is Pb or Bi, x is 0.05 ≦ x <0.5, and A is composed of Sr and Ba, and Sr / Ba is an atomic ratio of Sr and Ba forming A. The ratio is 0.5 to 1.5, wherein D is at least one element selected from Mg, Ca, and alkali elements, u is 0 <u ≦ 0.5, and z is 10 <z <12 and has a layer structure of 1234. Or
In Formula Tl _1-x M _x A ₂ Ca ₃ Cu ₄ O _z , M is an element selected from Ti, Mn, Ge, Sn, V, Sb, Te, Ru, in addition to Pb, and is substituted with Pb. And [substituted element] / Pb ratio, in which an elemental ratio other than Pb is substituted with Pb, is 0.3 to 0.5, x is 0.05 ≦ x <0.5, and A is Sr and Ba. Sr / Ba ratio, which is an atomic ratio of Sr and Ba constituting A, is 0.5 to 1.5, and z has a layer structure of 1234 on 10 <z <12, or
In Formula Tl _1-x M _x A ₂ Ca ₃ Cu ₄ O _z , M is any one selected from In, Cr and alkali elements, x is 0.05 ≦ x <0.5, and A is Sr and Ba. The Sr / Ba ratio, which is the atomic ratio of Sr and Ba of A, is 0.5 to 1.5, and z is 10 <z <12, and has a layer structure of 1234.
In addition, the superconductor powder and the superconductor bulk according to the present invention are characterized in that each made of the superconductor composition.

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In addition, the method for producing a superconductor bulk according to the present invention comprises an oxide comprising A-Ca-Cu, an oxide comprising AD-Ca-Cu, an oxide comprising MA-Ca-Cu and MAD-Ca-Cu A first step of making a precursor powder from at least one material selected from oxides; Synthesizing superconducting precursor powder of Tl-MA-Ca-Cu-O or Tl-MAD-Ca-Cu-O composition by mixing the oxide containing Tl and the oxide containing M to the precursor powder produced in the first step A second step; A third step of molding the superconducting precursor powder synthesized in the second step into a predetermined size; A fourth step of surrounding or sealing the bulk formed in the third step with a material which does not react with the bulk; A fifth step of heat-treating the bulk enclosed or sealed with the material in the fourth step at atmospheric pressure in a temperature range of 850 to 900 ° C .; And a sixth step of cooling the bulk heat-treated in the fifth step to room temperature, wherein the first step starts with nitride, carbide or oxide comprising at least one of composition elements M, A, D, Ca and Cu. A _2-u D _u Ca ₃ Cu ₄ O _z , A ₂ Ca _3-u D _u Cu ₄ O _z , M _x A _2-u D _u Ca ₃ Cu ₄ O _z and M _x A ₂ A step 1-1 of selecting and mixing any one or more of Ca _3-u D _u Cu ₄ O _z ; A first 1-2 step of pulverizing the mixed material in the step 1-1 into powders so as not to enter the material of the container to grind into several micro-sized powders; A first to third step of homogeneously mixing the powder by adding a liquid made of any one of volatile substances including ethyl alcohol and acetone to the powder produced in the first and second steps; A first to fourth steps of evaporating and pulverizing the liquid added in the first to third steps to form a powder and then molding the powder to a predetermined size; A first to fifth step of heat-treating the bulk formed in the first to fourth steps in an air or oxygen atmosphere at atmospheric pressure in a temperature range of 800 to 900 ° C. for 15 to 40 hours using a tubular electric furnace; 1-6 step of cooling the bulk heat-treated in the step 1-5 to room temperature; It comprises a first to seventh step to form a precursor powder by re-pulverizing the bulk cooled in the first to sixth step, in the second step the Tl-MA-Ca-Cu-O and the Tl-MAD- Ca-Cu-O is represented by Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _z or Tl _1-x M _x A ₂ Ca _3-u D _u Cu ₄ O _z , wherein M is Pb, Bi, In, Cr, Ti, Mn, Ge, Sn, V, Sb, Te, Ru and at least one element selected from alkali elements, A is composed of Sr and Ba, D is Mg, Ca and At least one element selected from alkali elements, x is 0.05 ≦ x <0.5, u is 0 <u ≦ 0.5, and z is 10 <z <12.

The superconductor composition and powder according to the present invention exhibits a critical temperature characteristic of about 100 K or more higher than the liquid nitrogen temperature of 77 K, so that the superconductor and superconductor are operated using liquid nitrogen which is a cheap refrigerant, or operate at a temperature above the liquid nitrogen temperature. It can be very useful for manufacturing and application of thin films and superconducting wires.

In addition, it is possible to synthesize a 1234-type structure, which was possible only under a high pressure, in a single phase even at normal pressure by the element substitution and synthesis method according to the present invention, thereby economically synthesizing a high temperature superconductor bulk (material). There is an advantage to this.

In addition, due to the ease of synthesis according to the present invention it can be usefully used for the understanding of superconducting properties, physical property improvement studies and the development of new superconductors.

Furthermore, the superconductor (composition, powder, bulk, hereinafter the same) according to the present invention has the advantage that the high-temperature superconductor is synthesized by the final heat treatment in a very short time compared to other Y-based or Bi-based superconductor shortening the manufacturing time, as well as heat treatment Since the superconductivity of the city is stable compared to the Y-based or Bi-based superconductor, it can be usefully used for developing superconducting parts requiring durability.

Finally, the method for manufacturing a superconductor bulk according to the present invention can reduce the amount of Tl which is a volatile and rare element by substituting a part of Tl with M element in the synthesis process and by minimizing the evaporation of Tl during synthesis. In addition, the problems related to securing and stability of raw materials of Tl have also been solved.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, since these embodiments are intended to specifically describe the present invention, the scope of the present invention is not limited to these embodiments.

The final sintered body (bulk) according to the manufacturing method of the present invention may be in any shape, but by applying a pressure of about 4 tons per cm ² made into a tablet form of a specimen of diameter 13mm, thickness 3mm, the specimen after heat treatment Was quenched to room temperature. The quenched specimen was cut back into a cuboid shape and partly pulverized into a powder to measure physical properties.

The structure of the specimen was measured using an X-ray diffractometer (Bruker D5005) and CuKα rays, and the resistivity of the specimen was measured by applying a current of 10 mA using the 4-point probe method and the temperature of the specimen. The temperature was controlled using a helium gas refrigerator (CTI-22 Cryodyne Refrigerator) and a temperature controller (LakeShore 330), and the temperature of the specimen was measured by a Si-diode thermometer installed at the same position as the specimen. ac susceptibility was measured using a Hartshorn type bridge using a 150 Hz and 1 Oe alternating field.

<Regarding Superconductor Composition Example >

First, the superconductor composition according to the present invention has a composition formula such as the following formula (1) or (2).

[Formula 1]

Tl _{1 - x} M _x A _{2 - u} D _u Ca ₃ Cu ₄ O _z

[Formula 2]

Tl _{1 - x} M _x A ₂ Ca _{3 - u} D _u Cu ₄ O _z

In Formulas 1 and 2, M is at least one element selected from Pb, Bi, In, Cr, Ti, Mn, Ge, Sn, V, Sb, Te, Ru, and alkali elements, x is 0.05 ≦ x <0.5, A is composed of Sr and Ba, D is at least one element selected from Mg, Ca and alkali elements, and u is 0 ≦ u ≦ 0.5.

Accordingly, M and D in Formulas 1 and 2 may be selected by dividing the composition ratio by selecting one or two or more of the elements listed above, and in Formula 2, D is substituted with Ca instead of A in Formula 1 If u = 0, the two formulas are the same.

Here, the Sr / Ba ratio, which is the atomic ratio of Sr and Ba of A, is preferably 0.33 to 1.66, more preferably 0.5 to 1.5.

In addition, the M preferably includes at least Pb or Bi, but when the M is Pb, any one element selected from Bi, Ti, Mn, Ge, Sn, V, Sb, Te, and Ru, in addition to Pb, may be used. It is more preferable that [substituted element] / Pb ratio which is comprised by substituting and which is an atomic ratio whose element other than said Pb is substituted with said Pb is 0.3-0.5.

Of course, the M may be any element selected from Pb, Bi, In, Cr and alkali elements.

And z is preferably 10 <z <12 or 11 ± δ (0 <δ <1).

Furthermore, x is 0.2 to 0.3, and the composition preferably has a 1234 single phase layer structure.

Embodiments of the various superconductor compositions are based on the following specific embodiments.

<Specific Regarding Superconductor Composition Example  1>

It is represented by Formula 1 or Formula 2 M = Pb, In the case of Sr / Ba ratio = 1, x = 0.3, u = 0, it is represented by following formula (3).

[Formula 3]

_{Tl 0 .7 Pb 0 .3 SrBaCa 3} Cu 4 O Z

In the superconductor composition represented by Chemical Formula 3, as a result of X-ray diffraction analysis, as shown in FIG. 1, it was confirmed that the layer structure of the 1234 phase was formed almost as a single phase.

In addition, according to FIG. 2, which is an ac susceptibility characteristic curve, the superconductor composition according to the present example exhibits clearly diamagnetic properties, and the critical temperature analyzed from the result of the specimen before heat treatment is about 107.4 K, which is measured as a specific resistance. Compared with the values of T _c (R = 0) = 102.2 K and T _c (onset) = 107.7 K, these values are almost identical to those of T _c (onset), which were observed in other specimen measurements. Therefore, it was found that T _c (onset) could be the highest critical temperature of the specimen.

In particular, Figure 2 shows the ac susceptibility measured after the first heat-treatment of the specimen in order to sequentially heat treatment at 300 ℃ and 400 ℃ for 12 hours in an oxygen atmosphere of about 1 atmosphere at 300 ℃, respectively for 6 hours The results of the measurement (ac susceptibility measurements were measured after quenching to liquid nitrogen temperature after each heat treatment), through which the superconductor composition according to the present embodiment almost did not change the characteristics of these oxygen and nitrogen atmosphere heat treatment And it was found.

As a result, the superconductor composition according to the present embodiment is Y-based or Bi-based [HKLee, K. Park and DHHa, " Effect of temperature and atmosphere on stability of high-T _c phases in Bi-Pb-Sr-Ca-Cu-O superconductors "J. Appl. Phys. 70, 2764-2767 (1991)] It was confirmed for the first time that the relatively stable characteristics compared to the specimen.

<Specific Regarding Superconductor Composition Example  2>

This is represented by the following formula (4) in the case of M = Pb, x = 0.2, u = 0, y = 0.4 to 2.0 in the formula (1) or formula (2).

[Formula 4]

_{Tl 0 .8 Pb 0 .2 Sr 2} - y Ba y Ca 3 Cu 4 O Z (y = 0.4 ~ 2.0)

FIG. 3 shows the X-ray diffraction pattern of the superconductor composition represented by Chemical Formula 4 by changing y values from 0.4 to 2.0.

Y = 0.4 in FIG. 3 The diffraction peaks observed in the specimens were observed as the main diffraction peaks of the conventional diffraction peaks on Tl-1223 and some impurities were observed. Using the peaks of the Miller-indexed Tl-1223 phase, the lattice constant of the specimen calculated by the least squares method was a = 3.812 (1) Å, c = 15.368 (8) Å [where the number in () is the last digit. Error, same below].

In addition, the diffraction peaks observed in y = 1.0 specimens were mirrored on Tl-1234, and the lattice constants calculated by the least-squares method were a = 3.827 (1) Å and c = 18.66 (2) Å.

The distinction between the 1223 phase and the 1234 phase is evident in FIG. 3, but is simply due to the difference in Miller Index pacing, while the 001 (Miller Index, below) peak on the 1223 phase is observed at 2Θ = 5.8 °, whereas for the 1234 phase Can be distinguished by the difference that the 001 peak is observed at 2Θ = 4.8 °.

Therefore, the result of FIG. 3 is a nominal configuration of (Tl, Pb) -1234 substituted with a certain amount of Pb, and when the specimen is synthesized by the above-mentioned method, the Ba y value of Ba is less than 0.75, whereas mainly 1223 phase is formed. When the substitution amount of 0.8 or more, 1234 starts to form, and the substitution amount of Ba mainly shows that the 1234 phase is well formed up to 1.5.

However, the Ba substitution amount is 2.0, indicating that there is no Sr and that 1234 phase is hardly formed.

As a result, Figure 3 shows that when the specimen is heat-treated and synthesized by the method according to the present invention, 1234 phase can be formed under normal pressure, and the formation of the 1234 phase is important to appropriately control the substitution amount of Ba or the ratio of Sr and Ba. Instruct

4 is Tl _{0 .8} Pb _{0 .2} Sr ₂ shown in Figure 3 _- shows the _y Ba _y Ca ₃ Cu ₄ O _z typical specific resistance characteristics of the specimen. This result shows that all the specimens on 1234 on which Pb is substituted show the superconducting transition, the metal temperature dependence in the steady state, and the critical temperature T _{c at} which the superconducting resistance becomes zero. (R = 0) is 99. 6 K, 101.2 K, 98.7 K and 102.1 K for y = 0.8, 1.0, 1.25 and 1.5, respectively, and the temperature T _c (onset) at which the superconducting transition begins is y = 0.8, 1.0 , 1.25 and 1.5 were 104.2 K, 105.8 K, 102.5 K and 107.5 K, respectively. In the case of y = 1.5, some impurities were observed, but the critical temperature was relatively high in the state where 1234 phase was the main component.

<Specific Regarding Superconductor Composition Example  3>

This is represented by the following formula (5) in the case of M = Bi, x = 0.2, u = 0, y = 0.4 to 1.5 in the formula (1) or formula (2).

[Formula 5]

_{Tl 0 .8 Bi 0 .2 Sr 2} - y Ba y Ca 3 Cu 4 O Z (y = 0.4 ~ 1.5)

FIG. 5 shows the X-ray diffraction pattern of the superconductor composition represented by Chemical Formula 5 by changing y values from 0.4 to 1.5.

Referring to FIG. 5, it is shown that even in the case of substituting Bi, phase formation characteristics change according to Ba substitution amount very similarly to Pb substitution, and in this case, 1234 phase is formed when y = 0.75 or more, and y = It is shown that almost single phase is formed in the 0.8 ~ 1.25 region, and 1234 phase is formed as the main phase even at y = 1.5.

Therefore, FIG. 5 shows that the substitution amount of Ba is very important for the formation of the 1234 phase, and indicates that the formation of the phase is not easy if the substitution amount of Ba is less than or equal to a certain level.

6 is Tl _{0 .8} Bi _{0 .2} Sr ₂ shown in Fig. ₅ shows the _y Ba _y Ca ₃ Cu ₄ O _z typical specific resistance characteristics of the specimen. This result is similar to the case where Pb is substituted, T _c (R = 0) is 103.9 K, 107.3 K, 104.4 k and 103.8 K for y = 0.8, 1.0, 1.25 and 1.5, and T _c (onset) is 112 for y = 0.8, 1.0, 1.2 and 1.5, respectively. 5 K, 114.2 K, 112.1 K and 110.0 K.

Therefore, the results of the resistivity measurement show that the specimens on 1234 with Pb and Bi substituted all have a critical temperature of about 100 K or more, and when the ratio of Sr / Ba is about 1, T _c It can be seen that the (R = 0) and T _c (onset) values are observed relatively high.

<Specific Regarding Superconductor Composition Example  4>

It is represented by Formula 1 or Formula 2 M = Pb, Sr / Ba ratio = 1, x = 0 to 0.5, u = 0 is represented by the following formula (6).

[Formula 6]

Tl _{1 - x} Pb _x SrBaCa ₃ Cu ₄ O _Z (x = 0 ~ 0.5)

FIG. 7 shows the X-ray diffraction pattern of the superconductor composition represented by Chemical Formula 6 by changing the x value from 0 to 0.5.

The results of FIG. 7 show that the Tl-1223 phase as well as the Tl-1223 phase are partially formed in the Pb-substituted specimen (x = 0). For reference, the coexistence of these two phases did not change significantly even when the experiment was performed by additionally changing the heat treatment time.

However, if the substitution amount x of Pb is 0.05 or more, the 1223 phase is decreased and mainly 1234 phase is observed compared to the specimen with x = 0 under the same experimental conditions.

If x = 0.5, some impurities are produced but shows that the 1234 phase is the predominant composition. This result indicates that the formation of phase 1234 is facilitated by the substitution of Pb when the composition ratio of Sr and Ba is constant.

In addition, when comparing the X-ray diffraction pattern of the specimen of x = 0 of Figure 7 and the results of Figure 5, it can be seen that not only an appropriate amount of Pb but also the substitution of Bi contributes to the formation on 1234.

On the other hand, the X-ray diffraction pattern of the specimen of x = 0 in Figure 7 X-ray diffraction observed in Figures 3 and 5 where Pb and Bi is substituted, compared to the partial formation of 1234 phase, even though Pb or Bi is not substituted When the substitution y value of Ba in the pattern is less than y = 0.75, the substitution amount of Ba or the appropriate composition ratio of Sr and Ba also plays a very important role in the formation of phase 1234 as compared with the formation of mainly Tl-1223 phase.

FIG. 8 shows the resistivity of the specimen shown in FIG. 7. The value of T _c (R = 0) is increased to about 7 K as the amount of Pb substitution increases compared to the case where Pb is not substituted, and the values of T _c (R = 0) of all Pb-substituted specimens are 100 K. The critical temperature was shown above.

<Specific Regarding Superconductor Composition Example  5>

9 shows X-ray diffraction patterns of superconductors having various compositions. 9 (a) is a case where M = In, Sr / Ba ratio = 1, x = 0.2, u = 0 in the formula (1), Figure 9 (b) is M = Cr, Sr / in the formula (1) In the case of Ba ratio = 0.6, x = 0.2, u = 0, Figure 9 (c) is a case in which M is an alkali element in the formula (1) M = Rb, Sr / Ba ratio = 1, x = 0.2, u = 0, and Figure 9 (d) is a case in which M = Pb, Sr / Ba ratio = 0.9, x = 0.2, D = K, u = 0.1 in the formula (1), Figure 9 (e) In Formula 1, M = Pb, Sr / Ba ratio = 0.5, x = 0.2, D = Mg, u = 0.5, and FIG. 9 (f) shows M = Pb, Sr / Ba ratio = In the case of 1, x = 0.3, D = Mg, u = 0.2, they all show nearly single phase 1234 phase X-ray diffraction patterns. The results of measurement of the resistivity of these specimens are shown in FIG. 10, where T _c (R = 0) is 105.3 K for (a), (b), (c), (d), (e) and (f), respectively. , 90.3 K, 100.8 K, 101.6 K, 105.5 K, and 101.9 K, and T _c (onset) is 108.8 K for (a), (b), (c), (d) (e), and (f), respectively. , 102.0 K, 107.8 K, 104.3 K, 109.0 K and 100.7 K.

<Specific Regarding Superconductor Composition Example  6>

11 and 13 illustrate a case in which M in Formula 1 includes Pb and other elements, and Sr / Ba ratio = 1, x = 0.2, u = 0, and is represented by Formula 7.

[Formula 7]

Tl _0.8 Pb _0.15 M _0.05 SrBaCa ₃ Cu ₄ O _z

(A), (b), (c), (d), and (e) of FIG. 11 are cases where M in the general formula (7) is Bi, Ti, Mn, Ge, and Sn, and FIG. 13 (a), (b), (c) and (d) in the case of M in the formula (7) is V, Sb, Te and Ru, respectively. All of these specimens show almost single phase 1234 phase X-ray diffraction patterns, indicating that the aforementioned elements can be utilized to form phase 1234. 12 shows the resistivity characteristics of the specimens shown in FIG. 11, and T _c (R = 0) is 101.2 K, 102.4 K, 102.4 K, 104.5 K and 99.8 K for (a), (b), (c), (d) and (e) respectively, and T _c (onset) is For (a), (b), (c), (d) and (e) they are 106.0 K, 105.8 K, 105.7 K, 107.8 K and 104.6 K, respectively. 14 shows the resistivity of the specimens shown in FIG. 13, and T _c (R = 0) is 97.2 K, 103.7 K, 103.0 K and 102.6 K for (a), (b), (c) and (d) respectively, and T _c (onset) is (a), (b) , (c) and (d) are 102.8 K, 109.3 K, 108.5 K and 107.0 K, respectively.

Superconductor Powder Example >

It is a superconductor powder consisting of a composition according to the embodiment of the superconductor composition has a micro size.

Superconductor Bulk Example >

It may have any size as a superconductor bulk (sintered body) consisting of the composition according to the embodiment relating to the superconductor composition. It can be used variously as a high temperature superconductor material.

<Method of manufacturing superconductor bulk Example >

The method for producing a superconductor bulk according to the present invention basically comprises an oxide comprising A-Ca-Cu, an oxide comprising AD-Ca-Cu, an oxide comprising MA-Ca-Cu and MAD-Ca-Cu A first step of making a precursor powder from any one or more materials selected from oxides; Synthesizing superconducting precursor powder of Tl-MA-Ca-Cu-O or Tl-MAD-Ca-Cu-O composition by mixing the oxide containing Tl and the oxide containing M to the precursor powder produced in the first step A second step; A third step of molding the superconducting precursor powder synthesized in the second step into a predetermined size; A fourth step of surrounding or sealing the bulk formed in the third step with a predetermined material; A fifth step of heat-treating the bulk enclosed or sealed in the fourth step at atmospheric pressure for 20 minutes to 7 hours at a temperature of 850 to 900 ° C .; The sixth step of cooling the bulk heat-treated in the fifth step to room temperature, wherein M is Pb, Bi, In, Cr, Ge, Sn, Sb, Te, Se, Ti, V, Mn, Ru and alkali At least one element selected from the elements, A is composed of Sr and Ba, and D is at least one element selected from Mg, Ca and alkali elements.
Here, the first step may be more specifically configured as the following step.
A _2-u D _u Ca ₃ Cu ₄ O _z , A ₂ Ca _3-u D _u synthesized using nitrides, carbides, or oxides containing at least one of the elements M, A, D, Ca, and Cu as starting materials Step 1-1 of mixing any one or more of Cu ₄ O _z , M _x A _2-u D _u Ca ₃ Cu ₄ O _z and M _x A ₂ Ca _3-u D _u Cu ₄ O _z ; A first 1-2 step of pulverizing the mixed material in the first step into a predetermined container into a micro-size to powder; A first to third step of mixing the powder homogeneously by adding a predetermined liquid to the powder made in the first and second steps; A first to fourth steps of evaporating and pulverizing the liquid added in the first to third steps to form a powder and then molding the powder to a predetermined size; A first to fifth step of heat-treating the bulk formed in the first to fourth steps in an air or oxygen atmosphere at atmospheric pressure in a temperature range of 800 to 900 ° C. for 15 to 40 hours using a tubular electric furnace; 1-6 step of cooling the bulk heat-treated in the step 1-5 to room temperature; It comprises a first to seventh step to form a precursor powder by re-pulverizing the bulk cooled in the first to sixth step, in the second step the Tl-MA-Ca-Cu-O and the Tl-MAD- Ca-Cu-O is Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _z or Tl _1-x M _x A ₂ Ca _3-u D _u Cu ₄ O _z , wherein x may be 0.05 ≦ x <0.5, and u may be 0 <u ≦ 0.5.

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In this case, in the first step, the precursor powder made in the first to seventh steps may be repeated at least once or more from the first to the first to the first to seventh steps.

In addition, in the first step, the predetermined container is a trigger provided so that the material of the container does not enter during the pulverization of the mixture, and in the first 1-2 steps, the predetermined liquid is one of volatile substances including ethyl alcohol and acetone. Either one of the materials that surrounds or seals the bulk formed in the fourth step may be more specifically silver or gold that does not react with the bulk.

Finally, the bulk cooled in the sixth step may be pulverized again and may be repeated at least once from the third step to the sixth step.

In addition, the specific element selection according to the present embodiment is in accordance with the general examples and specific examples 1 to 6 for the superconductor composition, and each result thereof is also based on FIGS. 1 to 14.

Since the contents of each of the other steps are known in the art, detailed description thereof will be omitted.

1 is _{Tl 0 .7 Pb 0, 3 SrBaCa} 3 Cu 4 O z X-ray diffraction pattern analysis results of the specimen represented by

FIG. 2 is a resistivity characteristic diagram according to the temperature of the specimen shown in FIG. 1,

Figure 3 is a _{Tl 0 .8 Pb 0, 2 Sr} 2 - y Ba y Ca 3 Cu 4 O z , it expressed in X-ray diffraction pattern analysis of the specimens,

4 is a resistivity characteristic diagram according to the temperature of the specimens shown in FIG.

5 is _{Tl 0 .8 Bi 0 .2 Sr 2} - y Ba y Ca 3 Cu 4 O z , expressed in X-ray diffraction pattern analysis of the specimens,

FIG. 6 is a resistivity characteristic chart of temperature of the specimens shown in FIG. 5; FIG.

7 is represented by Tl _{1 - x} Pb _x SrBaCa ₃ Cu ₄ O _z X-ray diffraction pattern analysis of the specimens,

FIG. 8 is a specific resistance chart according to temperature of the specimens shown in FIG. 7;

9 is represented by Tl _{1 - x} M _x A _{2 - u} D _u Ca ₃ Cu ₄ O _z or Tl _{1 - x} M _x A ₂ Ca _{3 - u} D _u Cu ₄ O _z X-ray diffraction pattern analysis of the specimens,

FIG. 10 is a resistivity characteristic chart of temperature of the specimens shown in FIG. 9. FIG.

11 and 13 are _{Tl 0 .8 Pb 0 .15 M 0} .05 SrBaCa 3 Cu 4 O z Represented by X-ray diffraction pattern analysis of the specimens,

12 is a resistivity characteristic diagram according to the temperature of the specimens shown in FIG. 11,

FIG. 14 is a resistivity characteristic chart of temperature of the specimens shown in FIG. 13. FIG.

Claims (19)

delete delete In formula Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _z or Tl _1-x M _x A ₂ Ca _3-u D _u Cu ₄ O _z , M is Pb or Bi, X is 0.05 ≦ x <0.5, A consists of Sr and Ba, Sr / Ba ratio of the atomic ratio of Sr and Ba forming the A is 0.5 to 1.5, D is at least one element selected from Mg, Ca and alkali elements, U is 0 <u ≦ 0.5, The z has a layer structure of 1234 phase as 10 <z <12, characterized in that the superconductor composition. In formula Tl _1-x M _x A ₂ Ca ₃ Cu ₄ O _z , M is composed of any element selected from Ti, Mn, Ge, Sn, V, Sb, Te, and Ru in addition to Pb, and is substituted with Pb, [Substituted element] / Pb ratio whose atomic composition ratio (atomic ratio) in which elements other than said Pb are substituted with said Pb is 0.3-0.5, X is 0.05 ≦ x <0.5, A consists of Sr and Ba, Sr / Ba ratio of the atomic ratio of Sr and Ba forming the A is 0.5 to 1.5, The z has a layer structure of 1234 phase as 10 <z <12, characterized in that the superconductor composition. In formula Tl _1-x M _x A ₂ Ca ₃ Cu ₄ O _z , M is any one selected from In, Cr, and alkali elements, X is 0.05 ≦ x <0.5, A consists of Sr and Ba, Sr / Ba ratio of the atomic ratio of Sr and Ba forming the A is 0.5 to 1.5, The z has a layer structure of 1234 phase as 10 <z <12, characterized in that the superconductor composition. delete The method according to any one of claims 3 to 5, The x is 0.2 to 0.3 superconductor composition, characterized in that. delete delete A superconductor powder comprising the superconductor composition of claim 7. delete delete A superconductor bulk, comprising the superconductor composition of claim 7. delete delete The precursor powder is made of at least one material selected from oxides comprising A-Ca-Cu, oxides containing AD-Ca-Cu, oxides containing MA-Ca-Cu and oxides containing MAD-Ca-Cu. A first step; Synthesizing superconducting precursor powder of Tl-MA-Ca-Cu-O or Tl-MAD-Ca-Cu-O composition by mixing the oxide containing Tl and the oxide containing M to the precursor powder produced in the first step A second step; A third step of molding the superconducting precursor powder synthesized in the second step into a predetermined size; A fourth step of surrounding or sealing the bulk formed in the third step with a material which does not react with the bulk; A fifth step of heat-treating the bulk enclosed or sealed with the material in the fourth step at atmospheric pressure in a temperature range of 850 to 900 ° C .; Including the sixth step of cooling the bulk heat-treated in the fifth step to room temperature, The first step is, A _2-u D _u Ca ₃ Cu ₄ O _z , A ₂ Ca _3-u D _u synthesized using nitrides, carbides, or oxides containing at least one of the elements M, A, D, Ca, and Cu as starting materials 1-1 step of selecting and mixing any one or more of Cu ₄ O _z , M _x A _2-u D _u Ca ₃ Cu ₄ O _z and M _x A ₂ Ca _3-u D _u Cu ₄ O _z ; A first 1-2 step of pulverizing the mixed material in the step 1-1 into powders so as not to enter the material of the container to grind into several micro-sized powders; A first to third step of homogeneously mixing the powder by adding a liquid made of any one of volatile substances including ethyl alcohol and acetone to the powder produced in the first and second steps; A first to fourth steps of evaporating and pulverizing the liquid added in the first to third steps to form a powder and then molding the powder to a predetermined size; A first to fifth step of heat-treating the bulk formed in the first to fourth steps in an air or oxygen atmosphere at atmospheric pressure in a temperature range of 800 to 900 ° C. for 15 to 40 hours using a tubular electric furnace; 1-6 step of cooling the bulk heat-treated in the step 1-5 to room temperature; It comprises a first to seventh step to form a precursor powder by pulverizing again the bulk cooled in the first to sixth step, In the second step, the Tl-MA-Ca-Cu-O and the Tl-MAD-Ca-Cu-O are Tl _1-x M _x A _2-u D _u Ca ₃ Cu ₄ O _z or Tl _1-x Represented by M _x A ₂ Ca _3-u D _u Cu ₄ O _z , M is at least one element selected from Pb, Bi, In, Cr, Ti, Mn, Ge, Sn, V, Sb, Te, Ru, and alkali elements, A consists of Sr and Ba, D is at least one element selected from Mg, Ca and alkali elements, X is 0.05 ≦ x <0.5, U is 0 <u ≦ 0.5, The z is a method for producing a superconductor bulk, characterized in that 10 <z <12. The method of claim 16, The first step is, The method of manufacturing a superconductor bulk, characterized in that for repeating the precursor powder produced in the step 1-7 again at least once or more from the step 1-4 to the step 1-7. The method of claim 16, And the material surrounding or sealing the molded bulk in the fourth step is silver or gold. The method of claim 16, The method of manufacturing a superconductor bulk, characterized in that to repeat the bulk cooled in the sixth step and to repeat at least one or more times from the third step to the sixth step.

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