Room-temperature and atmospheric-pressure superconducting ceramic compound and method for producing the same

Abstract

To provide a superconducting ceramic compound that exhibits superconducting properties at room temperature and atmospheric pressure.SOLUTION: A superconducting ceramic compound comprises a ceramic compound having an apatite crystal structure represented by Chemical Formula 1. <Chemical Formula 1>AaBb(EO4)cXd, wherein A, E, and X are elements constituting apatite minerals, B is a substituent and is an element having d orbitals, A comprises Pb, B comprises Cu, E comprises P and S, X comprises S or O, 0<a<10, 0<b<10, a+b=10, c=6, and 0<d≤4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a room-temperature, atmospheric-pressure superconducting ceramic compound and a method for producing the same, and more particularly, to a superconducting ceramic compound exhibiting superconducting properties at room temperature and atmospheric pressure and a method for producing the same.

Background Art

[0002] Modern times have seen such remarkable progress in technologies dealing with electrons that it is called the age of electricity and electronics. The fundamental aspect, of course, lies in a sufficient supply of electric power based on power generation, transmission, and distribution, and has developed to technologies of primary batteries, secondary batteries, which are media capable of storing electric power, and wireless power transmission and reception, becoming the driving force behind the remarkable development of modern times.

[0003] However, issues such as preparing alternatives for the recently emerging environmental and energy problems and solving the problem of efficiency degradation caused by the high integration / high density of semiconductors have led to the necessity of finding new substances to replace / solve the existing method of solving problems by using low-resistance substances such as copper and gold.

[0004] One area of interest as an approach to this is the field of high-temperature superconductivity, which in 1986, Bednorz and Müller published a new class of superconducting materials with a critical temperature (Tc) higher than the limit of the critical temperature of the classical BCS theory, surprising the solid-state physics community [Bednorz, et al, Z Phys B 64, 189 (1986)]. These materials are ceramics consisting of copper oxide layers separated by buffer cations. In the original compound of Bednorz and Müller (LBCO), the buffer cations are lanthanum and barium. Paul Chu, inspired by their work, synthesized a similar material where the buffer ions are yttrium and barium. This material is YBCO, the first superconductor to have a Tc exceeding the boiling point of liquid nitrogen (77K) [Wu, et al, Phys Rev Lett 58, 908 (1987)].

[0005] Among reports of similar phase transitions, the highest critical temperature increase is known to be 203.5K shown by hydrogen sulfide at a pressure of 155GPa. [Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system. Nature 525, 73 (2015).]

[0006] Subsequent related research using similar materials has continued, with the critical temperature increasing, and in 2020, a superconducting material with a critical temperature close to room temperature of 15°C was reported, but it requires a very high pressure of 267GPa. As a result of repeated efforts to relatively lower the pressure, in 2021, when a pressure of 186GPa was applied, a material showing superconducting properties at about minus 5°C was reported, but it is considered difficult to apply in real life in such a way (https: / / en.Wikipedia.org / wiki / Room-temperature_superconductor).

[0007] The reason is that, based on the experimental results of such hydrogen sulfide series and yttrium superhydrides, it is a fact that there is great expectation for room-temperature superconductors in the academic community. However, 267 GPa and 186 GPa correspond to pressures approximately 200,000 times that of atmospheric pressure (1 atm). When converted to weight, more than 2,700 tons are applied to an area of 1 cm 2 and it is considered almost impossible to utilize this industrially by itself.

[0008] Therefore, it is necessary to develop a superconducting substance that can be used not only at room temperature but also at normal pressure. This means that only substances that do not belong to the hydrogen sulfide or yttrium superhydride series, in other words, substances that do not require high pressure, will have high applicability and increased industrial usability.

[0009] In an invention already filed, the inventors have disclosed a substance containing a small amount of a room-temperature and normal-pressure superconducting substance having a critical temperature of 313 K. Although the fact that a superconducting substance was contained was confirmed through magnetic properties and MAMMA analysis, due to the small amount contained, the electrical properties specific to superconductivity were confirmed, albeit insufficiently.

Summary of the Invention

Problems to be Solved by the Invention

[0010] Therefore, the first technical problem to be solved by the present invention is to provide a superconducting ceramic compound that exhibits superconducting properties at room temperature and normal pressure.

[0011] Further, the second technical problem to be solved by the present invention is to provide a method for manufacturing a superconducting ceramic compound that exhibits superconducting properties at room temperature and normal pressure.

[0012] Together, the third technical problem to be solved by the present invention is to provide a solid-phase manufacturing method for a superconducting ceramic compound that exhibits superconducting properties at room temperature and normal pressure.

Means for Solving the Problems

[0013] In order to solve the above-described first technical problem, the present invention discloses a room-temperature and atmospheric-pressure superconducting ceramic compound characterized by containing a ceramic compound represented by Chemical Formula 1.

[0014] <Chemical Formula 1> A a B b (EO4) c X d A: (s- or p-block metal) Ca, Ba, Sr, Sn, Pb, (such as lanthanide series) Y, La, Ce, or a combination thereof B: (d-block metal) Cu, Cd, Zn, Mn, Fe, Ni, Ag, or a combination thereof E: P, As, V, Si, B, S, or a combination thereof X: F, Cl, OH, O, S, Se, Te, or a combination thereof (a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4)

[0015] According to another embodiment of the present invention, the raw material may be a substance having Chemical Formula 1, and the weight thereof is weighed according to the molar ratio within the range of a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4.

[0016] According to another embodiment of the present invention, the raw material may be a ceramic precursor obtained by weighing the weight of a substance having Chemical Formula 1 according to the molar ratio within the range of a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4 and performing pre-treatment synthesis.

[0017] According to another embodiment of the present invention, the ceramic compound may have a white or black color.

[0018] According to another embodiment of the present invention, the ceramic compound may have a gray color.

[0019] According to another embodiment of the present invention, the magnetic susceptibility of the ceramic compound due to temperature change may exhibit superconducting characteristics.

[0020] According to another embodiment of the present invention, the ceramic compound may be one in which the magnetic susceptibility due to the change in the magnetic field exhibits superconducting characteristics.

[0021] According to another embodiment of the present invention, the ceramic compound may be one in which the current-voltage characteristics due to the change in temperature exhibit superconducting characteristics.

[0022] According to another embodiment of the present invention, the ceramic compound may be one in which the current-voltage characteristics due to the change in the magnetic field exhibit superconducting characteristics.

[0023] According to another embodiment of the present invention, the resistance-temperature characteristics due to the change in the temperature of the ceramic compound may exhibit superconducting characteristics.

[0024] According to another embodiment of the present invention, B of the ceramic compound may be substituted at the position of A or enter between the vacant spaces in terms of crystal structure.

[0025] On the other hand, the present invention provides a method for manufacturing a superconducting ceramic compound, which includes a step of depositing raw materials in a vacuum state to synthesize a ceramic compound represented by Chemical Formula 1.

[0026] <Chemical Formula 1> A a B b (EO4) c X d A: (s- or p-block metal) Ca, Ba, Sr, Sn, Pb, (such as lanthanide series) Y, La, Ce, or a combination thereof B: (d-block metal) Cu, Cd, Zn, Mn, Fe, Ni, Ag, or a combination thereof E: P, As, V, Si, B, S, or a combination thereof X: F, Cl, OH, O, S, Se, Te, or a combination thereof (a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4)

[0027] According to another embodiment of the present invention, the raw material may be a substance having Chemical Formula 1 weighed according to the molar ratio in the ranges of a: 0 to 10, b: 0 to 10, c: 0 to 6, and d: 0 to 4.

[0028] According to another embodiment of the present invention, the vapor deposition may be heating at a reaction temperature of 550°C to 2000°C.

[0029] According to another embodiment of the present invention, the raw material may be a ceramic precursor which is weighed according to the molar ratio in the ranges of a: 0 to 10, b: 0 to 10, c: 0 to 6, and d: 0 to 4 for a substance having Chemical Formula 1 and pre-treated and synthesized.

[0030] According to another embodiment of the present invention, the ceramic precursor may be pre-treated by reacting at a reaction temperature of 550°C to 1100°C.

[0031] On the other hand, the present invention provides a method for producing a superconducting ceramic compound, including a step of reacting lanarkite (L, Lanarkite (Pb2SO5 = PbO·PbSO4)) with copper phosphide (Cu3P) to synthesize a ceramic compound represented by Chemical Formula 1, in order to solve the above-described third technical problem.

[0032] According to another embodiment of the present invention, the temperature during the reaction may be 600°C to 1000°C.

[0033] According to another embodiment of the present invention, the lanarkite may be weighed according to the composition of PbO and PbSO4, mixed, and heated.

[0034] According to another embodiment of the present invention, the synthesis of Cu3P may be weighing Cu and P according to the composition ratio, mixing, and heating.

[0035] Also provided is a superconducting ceramic compound characterized by containing a ceramic compound represented by Chemical Formula 1, which is produced by the above-described production method.

[0036] <Chemical Formula 1> A a B b (EO4) c X d A: (s- or p-block metal) Ca, Ba, Sr, Sn, Pb, (such as lanthanide series) Y, La, Ce, or a combination thereof B: (d-block metal) Cu, Cd, Zn, Mn, Fe, Ni, Ag, or a combination thereof E: P, As, V, Si, B, S, or a combination thereof X: F, Cl, OH, O, S, Se, Te, or a combination thereof (a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4)

[0037] According to another embodiment of the present invention, the raw material may be a substance having Chemical Formula 1, and the weight is weighed according to the molar ratio in the range of a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4.

[0038] According to another embodiment of the present invention, the raw material may be a ceramic precursor obtained by weighing the weight according to the molar ratio in the range of a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4 for a substance having Chemical Formula 1 and performing pre-treatment synthesis.

[0039] According to another embodiment of the present invention, the ceramic compound may have a white or black tint.

[0040] According to another embodiment of the present invention, the ceramic compound may have a gray tint.

[0041] According to another embodiment of the present invention, the magnetic susceptibility of the ceramic compound due to temperature change may exhibit superconducting characteristics.

[0042] According to another embodiment of the present invention, the ceramic compound may have a magnetic susceptibility due to a change in magnetic field that exhibits superconducting properties.

[0043] According to another embodiment of the present invention, the ceramic compound may have current-voltage characteristics due to a change in temperature that exhibits superconducting properties.

[0044] According to another embodiment of the present invention, the ceramic compound may have current-voltage characteristics due to a change in magnetic field that exhibits superconducting properties.

[0045] According to another embodiment of the present invention, the resistance-temperature characteristics due to a change in temperature of the ceramic compound may exhibit superconducting properties.

[0046] According to another embodiment of the present invention, B of the ceramic compound may be substituted at the position of A or enter between the vacant spaces in terms of crystal structure.

Advantages of the Invention

[0047] According to the ceramic compound and its manufacturing method according to the present invention, there is an effect of exhibiting superconducting properties at normal temperature and normal pressure.

Brief Description of the Drawings

[0048]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figures 25 - 27

Figure 28

Figure 29

Figure 30

Figure 31

Figure 32

Figure 33

Figures 34 - 35

Figures 36 - 37

Figure 38

Figure 39

Figure 40

Figure 41

Figure 42

Mode for Carrying Out the Invention

[0049] Hereinafter, the present invention will be described in detail.

[0050] However, it should be noted that the technical terms used in the present invention are merely used to explain a specific embodiment and are not intended to limit the present invention.

[0051] In addition, technical terms used in the present invention shall be construed in the meaning generally understood by those having ordinary knowledge in the technical field to which the present invention pertains, unless otherwise defined in the present invention, and shall not be construed in an overly comprehensive meaning or an overly narrow meaning. When a technical term used in the present invention is an incorrect technical term that cannot accurately express the idea of the present invention, it shall be understood as being replaced by a technical term that can be correctly understood by those skilled in the art. General terms used in the present invention shall be construed according to the dictionary definition or in the context of the preceding and following sentences, and shall not be construed in an overly narrow meaning. Singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "composed of" or "including" shall not be construed as necessarily including all of the various components or various steps described in the invention. Some of the components or some of the steps may not be included, or it shall be construed that additional components or steps can be further included. In the description of the present invention, when it is determined that a specific description of related known technologies may obscure the gist of the present invention, the detailed description thereof shall be omitted.

[0052] Figure 1 is a photograph of the deposited shape of the ceramic compound according to the present invention, Figure 2 is an SEM photograph of the white region of the ceramic compound according to the present invention, Figure 3 is an SEM photograph of the bright (light) gray region of the ceramic compound according to the present invention, Figure 4 is an SEM photograph of the dark (dark) gray region of the ceramic compound according to the present invention, Figure 5 is an SEM photograph of the black region of the ceramic compound according to the present invention, Figure 6 is a diagram schematically showing the hue and composition of the ceramic compound for Figures 2 to 5 and conceptually showing the thickness, Figure 7 is an XRD graph of the ceramic compound according to the present invention, Figure 8 is a graph of the measured Raman spectrum of the ceramic compound according to the present invention, Figure 9 is a graph obtained by removing the background (BG) in Figure 8 and then comparing it with general apatite data, Figure 10 is a graph showing a method for judging the superconducting susceptibility data of the ceramic compound according to the present invention, Figure 11 is a graph showing a method for judging the superconducting resistance data of the ceramic compound according to the present invention, Figure 12 is a graph showing a method for judging the superconducting IV data of the ceramic compound according to the present invention, Figure 13 is M-T (magnetic susceptibility - temperature) data for a thin film showing the superconducting properties of the ceramic compound according to the present invention with a magnetic field of 0.12 Oe, Figure 14 is M-T (magnetic susceptibility - temperature) data for a thin film showing the superconducting properties of the ceramic compound according to the present invention with a magnetic field of 10 Oe, Figure 15 is a data graph showing the removal of the diamagnetic value of the skeletal material itself to view the magnetic susceptibility value of only superconductivity from the data of Figures 13 and 14, Figure 16 is a data graph of the measured magnetic susceptibility with the change of the magnetic field (H) of the ceramic compound according to the present invention, Figure 17 is an enlarged data graph of the portion indicated by the dotted circle in Figure 16, Figure 18 is a data graph showing the state where the linear fitting data is removed in Figure 16, Figure 19 is a data graph of the IV characteristics with the change of temperature of the ceramic compound according to the present invention, Figure 20 is an enlarged graph of the central dotted circle portion in Figure 19, Figure 21 is the IV characteristic data of the ceramic compound according to the present invention at a low temperature, Figure 22 isThis is a graph of the result of measuring IV while vertically applying a magnetic field change at 300 K to the ceramic compound according to the present invention. FIG. 23 is a graph of RT data obtained by measuring the resistance value (R) according to the change in temperature (T) of the ceramic compound according to the present invention. FIG. 24 is a photograph of a sample obtained by measuring SEM-EDX of the ceramic compound according to the present invention, and position numbers #1, #2, and #3 are shown from the left side to the right side. FIGS. 25, 26, and 27 are SEM photographs taken at position numbers #1, #2, and #3 in FIG. 24, respectively. FIG. 28 is data obtained by measuring SEM-EDX at position numbers #1, #2, and #3 in FIG. 24. FIG. 29 is a structural modeling of the ceramic compound according to the present invention, which is a diagram schematically showing the relationship between lead and copper two-dimensionally. FIG. 30 is a structural modeling of the ceramic compound according to the present invention, which is a diagram considering the three-dimensional arrangement of copper. FIG. 31 is a graph of the change in resistance according to the change in temperature of the ceramic compound by the solid-phase reaction according to the present invention. FIG. 32 is an XRD analysis graph of the ceramic compound by the solid-phase reaction according to the present invention. FIG. 33 is a graph showing the result of measuring I-V according to the change in temperature for Example 1 of the present invention. FIGS. 34 and 35 are SEM measurement photographs for Example 3 and Example 5, respectively. FIGS. 36 and 37 are graphs of the measured I-V changes for Example 3 and Example 5, respectively. FIG. 38 is a graph showing the superconducting characteristics according to the change in temperature for Example 4. FIG. 39 is a graph showing the superconducting characteristics according to the change in magnetic field for Example 4. FIG. 40 is a graph showing the RT characteristics according to the change in temperature for Example 4. FIG. 41 is SEM-EDX data measured at any two locations (#1, #2) for Example 4. FIG. 42 is a photograph of an experiment in which the resistance was measured in real time for Example 4, and the present invention will be described with reference to this.

[0053] The present invention further intends to disclose the crystal structure of only a small amount of superconducting substances that could not be publicly disclosed in the previously filed invention.

[0054] The present invention has found a method capable of increasing the amount of superconducting material in the form of a thin film through a vapor deposition (VD) method. Further analysis has confirmed the reaction mechanism and crystal structure of the superconducting material. Based on this information, superconducting materials can also be synthesized in the form of ingots or powders using general solid-phase reactions.

[0055] In addition, the various energy sources used for deposition are not limited to chemical vapor deposition (CVD) using heat, but also include atomic layer deposition (ALD), sputtering, thermal evaporation, electron beam evaporation, molecular beam epitaxy (MBE), pulsed laser deposition (PLD), etc., as long as they can deposit the raw materials, without limitation.

[0056] The present invention also discloses through repeated experiments that the superconducting material is a mixture of stable phases having two or more critical temperatures (Tc). This is similar to the reason that the YBCO phase with a critical temperature of 90K (about -180°C) is well-known, but the 60K (about -210°C) phase is also often produced. This is because even if the crystal structure is the same, a slight difference in the amount of oxygen (doping) changes the electronic structure and thus the critical temperature.

[0057] YBCO has a wide doping range for the 90K phase and the 60K phase, so these two phases are often formed. In the case of YBCO, it is known that the higher the oxygen partial pressure during synthesis, the more dominant the 90K phase becomes (https: / / www.researchgate.net / figure / YBCO-phase-diagram-as-a-function-of-the-oxygen-content-between-6-and-7-12_fig15_33436805).

[0058] The superconducting material according to the present invention also has the same crystal structure, but due to the difference in the electronic structure, there can be three stable phases with significantly different critical temperatures. That is, (1) 310K - 320K (about 40°C - 50°C): hereinafter, Tc_I, (2) 340K - 350K (about 70°C - 80°C): hereinafter, Tc_II, (3) 375K - 390K (about 100°C - 125°C): hereinafter, the regions can be divided into Tc_III.

[0059] Similar to YBCO, the above three phases all have the same crystal structure, but are considered to have different critical temperature characteristics due to subtle differences in the electronic structure, and the ratio of the three phases varies depending on the synthesis conditions.

[0060] The subtle differences in the electronic structure must accurately identify the position where the superconducting phenomenon occurs and belong to a very academic research scope such as quantum mechanical calculations, so it will not be discussed in more detail here.

[0061] In the thin film according to the present invention, through the measurement of resistance, changes in the critical temperatures of Tc_I and Tc_II were observed. For Tc_III, no clear transition was observed. In the measurement of magnetic susceptibility, changes were shown at Tc_II and Tc_III, but the signal was captured at Tc_III, which was not well seen in the resistance measurement. This is considered to be because the measurement of magnetic susceptibility is more sensitive than the measurement of resistance.

[0062] In addition, in the solid-phase reaction composite tried to confirm the mechanism of the thin film according to the present invention, Tc_III was observed to be the largest, and Tc_I and Tc_II were weakly observed, which means that the amount of Tc_III was surely increased.

[0063] A more detailed explanation of the above-mentioned Tc_I, Tc_II, and Tc_III regions will be described later.

[0064] The superconducting ceramic compound according to the present invention is characterized by including a ceramic compound represented by Chemical Formula 1.

[0065] <Chemical Formula 1> A a B b (EO4) c X d A: (s- or p-block metal) Ca, Ba, Sr, Sn, Pb, (such as lanthanide series) Y, La, Ce, or a combination thereof B: (d-block metal) Cu, Cd, Zn, Mn, Fe, Ni, Ag, or a combination thereof E: P, As, V, Si, B, S, or a combination thereof X: F, Cl, OH, O, S, Se, Te, or a combination thereof (a: 0 to 10, b: 0 to 10, c: 0 to 6, d: 0 to 4)

[0066] Although the Chemical Formula 1 has a surface structurally similar to apatite, since its physical properties and characteristics are different, in this patent, this structure is referred to as "LK99".

[0067] The apatite is a mineral in which a metal is bonded to a phosphate group or the like and has been commonly used as a dye for a long time. It is an electrical insulator with a large energy gap, while the LK99 structure according to the present invention forms new energy levels with substituents, dopants, and defects in the compound, and has the characteristics of an electrical conductor, particularly exhibiting superconducting properties.

[0068] In addition, A, E, and X in Chemical Formula 1 are common elements that make up apatite minerals (https: / / www.intechopen.com / books / apatites-and-their-synthetic-analogues-synthesis-structure-properties-and-applications / introduction-to-apatites). Here, B is a kind of substituent or added impurity, which is an element having a d-orbital, and thereby has the property of changing from an electrical insulator to a conductor or a superconductor.

[0069] That is, more specifically, A is a metal such as Ca, Ba, Sr, Sn, Pb, etc., having the characteristics of s-block metals or p-block metals, or Y, La, Ce, etc., and the metals include the lanthanum series, etc., or combinations thereof.

[0070] Also, B is Cu, Cd, Zn, Mn, Fe, Ni, Ag, etc., having the characteristics of d-block metals, E is P, As, V, Si, B, S, or combinations thereof, and X may be F, Cl, OH, O, S, Se, Te, or combinations thereof.

[0071] At the same time, a described above is 0 to 10, b is 0 to 10, c is 0 to 6, and d is 0 to 4. However, the meaning of '0' here can be regarded as the meaning of being able to exist, rather than meaning none (for example, 10 -10 (g)).

[0072] Also, the raw material is A of Chemical Formula 1 a B b (EO4) c X dThe substances forming it are weighed according to the molar ratio within the ranges of a being 0 to 10, b being 0 to 10, c being 0 to 6, and d being 0 to 4, and reacted in a reaction vessel capable of vacuum adjustment at a reaction temperature of 550°C to 2000°C for a reaction time of 1 to 100 hours so as to be vapor-phase deposited, whereby a ceramic compound can be synthesized.

[0073] In addition, the raw materials can be pretreated so that the vapor-phase deposition is effectively carried out densely and uniformly. Such a pretreatment is carried out on A of Chemical Formula 1 a B b (EO4) c X d The substances forming it are weighed according to the molar ratio within the ranges of a being 0 to 10, b being 0 to 10, c being 0 to 6, and d being 0 to 4, and reacted in a reaction vessel capable of vacuum adjustment at a reaction temperature of 550°C to 1100°C for a reaction time of 10 to 100 hours to obtain a pretreated ceramic precursor, which can be used as a vapor deposition raw material.

[0074] In the present invention, the process temperature and process time are as follows: (1) in the case of the ceramic precursor, 550°C to 1100°C and 10 to 100 hours, and (2) in the case of the vapor deposition process, 550°C to 2000°C and 0.5 to 100 hours. The reason is that in the case of the ceramic precursor, primarily, reaction conditions are set at a relatively low temperature (550°C to 1100°C) stably according to the composition ratio so that the reaction occurs in a well-mixed solid-solution state, and since it is a precursor to be primarily prepared for use as a vapor deposition raw material.

[0075] Here, if the heating temperature of the ceramic precursor is less than 550°C, sufficient mixing may not occur, and as a result, the desired reaction may not occur sufficiently. On the contrary, if it exceeds 1100°C, the composition may change due to the high temperature, and there are problems such as proceeding to other reactions and not obtaining the desired composition, as well as the problem of energy waste. The heating time requires 10 to 100 hours. However, if it is less than 10 hours, similar to the case of low temperature, the problem is that a sufficient reaction does not occur. On the contrary, if it exceeds 100 hours, too much energy may be consumed, which can be a problem.

[0076] In the case of the vapor deposition process, the conditions for vapor deposition can be roughly divided into two types. One is CVD (Chemical Vapor Deposition method). A well-prepared sample (including the pretreatment substance) is placed in a vacuum state on the heating part, and an energy source is applied to raise the temperature to move it into the gas phase. At this time, if the temperature is less than 550°C, the vaporization of the substance that should be in the gaseous state does not occur well. If the temperature exceeds 2000°C, the temperature of the vapor deposition surface rises excessively, and the desired vapor deposition phase may not be formed well. The heating time is required to be 0.5 to 100 hours. If it is less than 0.5 hours, sufficient vaporization is difficult, so the vapor deposition may become thin. On the contrary, if it exceeds 100 hours, it may be energy-wasting after the vapor deposition is completed.

[0077] The other one may be a physical vapor deposition process including thermal evaporation with a heating temperature of 550 to 2000°C. If the temperature is less than 550°C, the elements cannot be vaporized sufficiently, and it is difficult to uniformly form a compound. On the contrary, if it exceeds 2000°C, it may be difficult to form a superconducting compound. The heating time is required to be 0.5 to 100 hours. If it is less than 0.5 hours, sufficient vaporization is difficult, so the vapor deposition may become thin. On the contrary, if it exceeds 100 hours, it may be energy-wasting after the vapor deposition is completed.

[0078] On the one hand, due to heating at high temperatures during the synthesis of the ceramic compound according to the present invention, as the formation and synthesis of the synthesized ceramic compound progress over a fine time period, there exists a temperature gradient of temperature deviation like natural cooling in the layers or domains of the product. However, a vapor deposition film may be formed in a specific temperature range (100°C to 400°C). A white film forms in the high-temperature part, a black film forms in the low-temperature part, and in the intermediate region, a film that appears gray with two films coexisting is formed. This colored ceramic compound can exhibit superconducting properties. In particular, the electrical properties specific to superconductivity are strongly expressed in the gray region, which means that the amount has been sufficiently formed to enable electrical percolation. Looking at the photograph of the deposited shape of the ceramic compound according to the present invention in the attached Figure 1, it can be seen that the region N close to the heat source S for heating the raw material has a white W color, the distant region F has a black B color, and the intermediate region M shows a gray G color.

[0079] Explaining the relationship between the ceramic compound according to the present invention and colors such as white, black, and gray through scanning electron microscope (SEM) photographs, the photographs in Figures 2 to 5 are SEM photographs taken with the generated ceramic compound tilted at an angle (about 45°). Figure 2 is for the white region of the ceramic compound according to the present invention, Figure 3 is for the bright (light) gray region, Figure 4 is for the dark (dark) gray region, and Figure 5 is for the black region.

[0080] The expression of such hues is related to the composition of the formed ceramic compound. The white region is dominated by lanarkite (Pb2SO5), and the black region is considered to be predominantly formed of PbS.

[0081] The reaction for forming lanarkite is considered to be that PbS vaporizes first and is formed by receiving oxygen supply from the substrate. The reaction formula is as follows.

[0082] 2PbS(s) + 5 / 2O2(s, from substrate) → Pb2SO5(s) + S(g)↑

[0083] Figure 6 schematically shows the hue and the composition of the ceramic compound with respect to FIGS. 2 to 5, and conceptually shows the thickness. The region N close to the heat source S for heating the raw material has a white color W and has a thickness of about 30 μm, and the far region F has a black color B and has a thickness of about 0.6 μm. The intermediate region M shows a bright and dark gray G because the black has a thickness of about 1.3 to 3.3 μm and the white has a thickness of about 4 to 30 μm, and it is considered that dark gray and light gray are expressed. However, whether it is simply due to the mixture of ceramic compounds showing their respective hues or due to the change in composition will be described later.

[0084] One explanation regarding such a composition can be described through the crystal structure analysis (XRD) of an X-ray diffractometer. FIG. 7 is an XRD graph of the ceramic compound according to the present invention, and particularly relates to the gray region M (2 (dark gray) in FIG. 6) where superconducting characteristics are exhibited. The black line in the graph is based on the measurement data (Experimental pattern). In contrast, it is a graph shown by matching with a thick line (Apatite) and a thin line (Lead Phosphate) using COD (Crystallography Open Database).

[0085] Here, the thick line matches with Apatite, which is a kind of phosphate mineral. Although there are some deviations in the peak positions, it shows that they generally match well. The thin line is lead phosphate, which is a small amount of side reaction product generated together during the synthesis of the ceramic compound of the present invention.

[0086] As can be seen from the graph of FIG. 7, the ceramic compound has the characteristic that its main component is similar to the structure of apatite. However, apatite is a white or slightly colored substance, and its electrical property is an insulator, not a conductor or superconductor according to the present invention. Therefore, it can be understood that ordinary apatite is different from the structure 'LK99' of the ceramic compound of the present invention.

[0087] In addition, for the gray region M (2 (dark gray) in FIG. 6) where the superconducting properties of the ceramic compound according to the present invention are clearly exhibited, if Raman is measured by arbitrarily selecting three points, the presence or absence of a phosphate group can be confirmed. FIG. 8 is a graph showing the Raman measurement of the ceramic compound according to the present invention. Referring to this, 1, 2, and 3 in the photo at the upper left end of the graph indicate the measured positions.

[0088] After removing the background (BG) from the graph of FIG. 8 and comparing it with the data of general apatite, the resulting graph is shown in FIG. 9. In FIG. 9, v1, v2, v3, and v4 represent the vibration modes of the PO4 molecule, which is a phosphate group. v1 is symmetric stretching, v2 is symmetric bending, v3 is antisymmetric stretching, and v4 is antisymmetric bending. It can be confirmed that the ceramic compound of the present invention has a phosphate group.

[0089] Continuing the explanation of the above-mentioned Tc_I, Tc_II, and Tc_III regions, as shown in FIGS. 10, 11, and 12, it is necessary to explain the method for judging the superconductivity of the ceramic compound.

[0090] That is, whether or not it is superconducting can be determined by measuring two major characteristics: 1) magnetic susceptibility (magnetic moment), and 2) determination based on resistance or IV (current-voltage) data.

[0091] Figure 10 shows the magnetic susceptibility data of superconductivity for the ceramic compound according to the present invention. When the temperature rises above the critical temperature (Tc), a transition occurs where the magnetic susceptibility value suddenly increases. This measurement method is called ZFC, and the method of measuring while lowering the temperature from a high temperature is called FC, which will be described in detail in the part of magnetic susceptibility measurement.

[0092] Figure 11 shows the resistance data of superconductivity for the ceramic compound according to the present invention. When the temperature drops below the critical temperature (Tc), a transition occurs where the resistance value suddenly decreases (theoretically going to zero '0'). However, even when the temperature starts from a low temperature and rises above the critical temperature, the same data can be obtained.

[0093] The characteristics understood from Figures 10 and 11 are all substances in a non-superconducting state above the critical temperature, and can appear in various patterns depending on the characteristics of the substance itself.

[0094] Figure 12 shows the IV data of superconductivity for the ceramic compound according to the present invention. It measures the voltage applied across both ends when the current is applied from (-) to (+) below the critical temperature (Tc). When the current flows below the critical current (-Ic to +Ic), the superconducting characteristic that the voltage is '0' is detected. Above the critical current, it is in a non-superconducting state and shows characteristics following Ohm's law like a normal substance.

[0095] Figures 13 and 14 are M-T (magnetic susceptibility-temperature) data for a thin film showing the superconducting properties of the ceramic compound according to the present invention. The data were measured by the VSM (Vibrating Sample Magnetometer) method with magnetic fields of 0.12 Oe and 10 Oe applied respectively, and the temperature was measured from 200 K to 400 K. Measuring by the VSM method has the advantage that very small signals of the sample can be captured, but it can show a low S / N ratio for such small signals.

[0096] Therefore, in the above data, for convenience of understanding, smoothing data in addition to the original data are shown in Figure 15.

[0097] ZFC (zero-field cooling) and FC (field cooling) are typical measurement methods for confirming the Meissner effect, which is the diamagnetic property of superconductivity. Specifically, 1) a method (ZFC) of measuring the magnetic susceptibility while increasing the temperature after lowering the temperature of the sample in a state where the external magnetic field is zero and then applying a certain magnetic field; 2) a method (FC) of measuring the magnetic susceptibility while lowering the temperature again while maintaining the applied magnetic field as it is; 3) unless it is a type-I superconductor such as a simple metal element, ZFC and FC show a difference, and there is a method of confirming whether ZFC shows a diamagnetic transition below the critical temperature, etc.

[0098] The ceramic compound according to the present invention has an intrinsic diamagnetism in its own constituent skeletal substances (such as phosphate groups, silicate groups, sulfate groups) in addition to the part where superconducting properties occur. Therefore, (1) the diamagnetic property of superconductivity and (2) the diamagnetic property of the original substance can be shown in a combined state.

[0099] That is, (1) exhibits a diamagnetic transition in which the diamagnetic property increases below the critical temperature, while (2) does not have such a transition. With respect to the change in the external magnetic field, (1) shows hysteresis, while (2) does not have such a property. When the external magnetic field becomes stronger, the diamagnetic property of (1) weakens or disappears, while (2) shows a property of increasing proportionally.

[0100] In addition to the properties of (1) and (2), a new (3) ferromagnetism appears in between. Although the cause of this ferromagnetism has not been studied in detail, the inventors of the present invention interpret it as a kind of proximity effect.

[0101] When other magnetisms other than superconductivity are combined in this way, in order to observe only the diamagnetic transition of superconductivity, the influence of other magnetisms must be minimized. Therefore, an experimentally possible method is to minimize the value of the external magnetic field applied for the measurement of magnetic susceptibility. The data in Fig. 13 were measured with an external magnetic field of 0.12 Oe (to adjust the magnetic field to this level, only an SQUID with a low-field option is possible), and the data in Fig. 14 were measured with an external magnetic field of 10 Oe.

[0102] Fig. 15 shows the data obtained by removing the diamagnetic value of the backbone material itself in order to view the magnetic susceptibility value of only superconductivity from the data in Fig. 13 and Fig. 14. The diamagnetic value of the backbone material itself is obtained for 0.12 Oe and 10 Oe from the linear fitting data of the magnetic susceptibility (magnetic moment) method in the determination method of whether it is superconductivity as described above (-1.03×10 -7 emu at 0.12 Oe, -4.06×10 -7 emu at 10 Oe).

[0103] Referring to FIGS. 13 to 15, in ZFC, the primary diamagnetic transition starts at about Tc_III, and there is a change in the slope that is also regarded as a second-order transition at Tc_II (indicated by the yellow arrow). The magnetic susceptibility value shows a negative number (diamagnetism), and it can be seen that the critical temperature decreases to about -325K with the increase of the external magnetic field, and the magnetic susceptibility value already shows a positive number (the influence of ferromagnetism).

[0104] Next, the magnetic susceptibility characteristics of the ceramic compound according to the present invention due to the change in magnetic field will be described through 'Magnetization measurements of the data measured by changing the magnetic field (H) (also referred to as M-H data, measurement equipment: SQUID-Vibration Sample Magnetometer, Quantum Design MPMS3)'.

[0105] FIG. 16 is a data graph of the measurement of the magnetic susceptibility of the ceramic compound according to the present invention by changing the magnetic field (H). FIG. 17 is an enlarged data graph of the part indicated by the dotted circle in FIG. 16. FIG. 18 is a data graph showing the state where the linear fitting data in FIG. 16 is removed. Referring to these figures, (a) The M-H hysteresis is measured between -3T and +3T. Overall, the diamagnetic characteristics of the apatite backbone material without hysteresis are observed. Linear fitting (shown as fitting data in FIG. 16) is performed to obtain the diamagnetic value of the backbone material. (b) It is an enlarged view of the part indicated by the central dotted circle. Hysteresis that was not present in the strong magnetic field region is observed. It is judged that this is not due to the backbone material but is a characteristic that appears when superconductivity is combined in the low magnetic field region. (c) It is the one with the linear fitting data removed from (a), and ferromagnetism is detected. Since the ferromagnetism has been described above, it will be replaced by that description here and omitted.

[0106] On the other hand, in order to explain the electrical characteristics of the ceramic compound according to the present invention, I-V (current-voltage) was measured by changing the temperature.

[0107] Figure 19 shows the IV characteristic data of the ceramic compound according to the present invention with respect to the change in temperature. The measurement was carried out by the four-terminal method, the interval between the probes is 1 mm, and the IV characteristics of the sample were observed for several intervals from 272 K to 343 K. A unique pattern that is only observed in superconductivity is seen.

[0108] Figure 20 is an enlarged graph of the central dotted circular part of Figure 19. The superconducting characteristics can be observed, showing an asymmetric graph with '0' as the reference. This is judged to appear due to the inhomogeneity of the thin film sample (such as thickness deviation, inclusion of non-superconducting substances acting as Josephson junctions, etc.).

[0109] Figure 21 shows the IV characteristic data of the ceramic compound according to the present invention at low temperatures. It can be seen that the symmetry increases and the asymmetry decreases significantly at low temperatures (261 K). Such IV asymmetry is also called IV hysteresis, and the causes are very diverse. The minimum resistivity is 10 -7 Ω·cm, but there is a residual resistance value. Therefore, it is judged that the symmetry will increase when the size of the ceramic compound becomes larger.

[0110] This is because when the particle size is small, there are many grain boundaries, which are the boundaries between particles, and this causes the residual resistance value.

[0111] On the other hand, in order to explain the electrical characteristics of the ceramic compound according to the present invention, the I-V characteristics with respect to the change in magnetic field will be further described. Figure 22 is a result graph of measuring the IV while vertically applying a change in magnetic field at 300 K for the ceramic compound according to the present invention (measurement equipment: Power (voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: four-terminal method (4-probe method)). It well shows the superconducting characteristic that the range of the critical current decreases as the magnetic field increases at a certain temperature below the critical temperature.

[0112] In addition, the measurement of the resistance (R-T (resistance-temperature)) of the ceramic compound according to the present invention due to the change in temperature is shown in FIG. 23.

[0113] FIG. 23 is a graph of RT data obtained by measuring the resistance value (R) according to the change in temperature (T) (measurement equipment: Power (voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: four-terminal method (4-probe method)). As described above, the ceramic compound according to the present invention has superconducting properties, and thus has three critical temperatures, namely, (1) 310K to 320K (about 40°C to 50°C above zero, Tc_I), (2) 340K to 350K (about 70°C to 80°C above zero, Tc_II), and (3) 375K to 390K (about 100°C to 125°C above zero, Tc_III). Phases with these critical temperatures exist. However, Tc_I and Tc_II are confirmed but not shown in the drawings. In the Tc_III region, no sharp change pattern regarded as a transition is observed, and only a shape that decreases broadly is observed. In a magnetic susceptibility measurement with better sensitivity, the Tc_III region was also observed (in the above-mentioned ZFC, a diamagnetic transition starts primarily at about Tc_III).

[0114] On the other hand, the solid-phase reaction of the ceramic compound according to the present invention will be further described.

[0115] First, for the analysis of the components of the ceramic compound according to the present invention, measurements were carried out using SEM-EDX (measurement equipment: FE-SEM, EDX), and the results are shown in FIGS. 24 to 27.

[0116] FIG. 24 is a photograph showing a sample obtained by measuring the SEM-EDX of the ceramic compound according to the present invention, and position numbers #1, #2, and #3 from the left to the right. The SEM photographs taken at each position are shown in FIGS. 25, 26, and 27.

[0117] Here, FIG. 28 shows data obtained by measuring SEM-EDX for component analysis, and it is a table showing the molar ratio (atomic%) of the elements compared to lead (Pb) which is the central metal.

[0118] Referring to the above table, for the measured position numbers #1, #2, and #3, the ratios of lead (Pb), copper (Cu), sulfur (S), phosphorus (P), oxygen (O), and silicon (Si) can be known. It can be seen that the original apatite has a weight ratio of lead to phosphorus (Pb:P) = 1:0.6, while the ceramic compound according to the present invention is about 1:0.4.

[0119] It can be seen that a part of the phosphorus (P) in apatite is replaced by other elements (for example, about P = 0.4, S = 0.2).

[0120] Also, it is determined that copper (Cu) is partially substituted at the position of Pb in apatite or is partially arranged as an impurity between the structures to form the structure 'LK99' of the present invention. The structure of LK99 can be modeled and shown in FIGS. 29 and 30.

[0121] FIG. 29 is a structural modeling of the ceramic compound according to the present invention, which schematically shows the relationship between lead and copper two-dimensionally. FIG. 30 is a structural modeling of the ceramic compound according to the present invention, which takes into account the three-dimensional arrangement of copper. Referring to these, the positions where copper (Cu) enters can be modeled in two types, namely, the case of substituting lead (Pb) and the case of entering between the vacant spaces in the structure. When substituting lead, as can be seen from FIG. 29, it can occur at either one or both of the two positions of Pb_1 and Pb_2. When entering between the vacant spaces, as can be seen from FIG. 30, it can occur at either one or both of the elliptical position (the space between the upper Pb_2 and the lower Pb_2) and the rectangular position (where part of O_2 is missing and it enters that position or the space between the adjacent O_2).

[0122] Also, although not shown in the drawings, sulfur (S) is present at the position of phosphorus (P) and partially replaces phosphorus.

[0123] In addition, through the analysis of the ceramic compound according to the present invention, several characteristics of the formation of the superconducting substance are as follows: (1) the superconducting substance is formed in the region where lanarkite is present; (2) both Cu and P are detected in the region of the superconducting substance; (3) among the compounds formed by Cu and P, the substance existing in the database (COD) is Cu3P; (4) therefore, it is found that lanarkite reacts with Cu3P to generate 'LK99', which is the structure of the superconducting substance that is the ceramic compound according to the present invention, and this can be shown by the following reaction formula.

[0124] <Reaction formula> L + Cu3P → LK99 (L: Lanarkite (Pb2SO5 = PbO·PbSO4))

[0125] The above reaction formula is the reaction mechanism of the ceramic compound according to the present invention. The structure of apatite does not exist only with sulfate groups, but exists in the form of phosphate groups alone or a mixture of phosphate groups and sulfate groups. Lanarkite is a sulfate group compound, but it is found that by reacting with Cu3P, part or all of the sulfur is replaced by phosphorus to form phosphate groups.

[0126] On the other hand, the synthesis of the ceramic compound according to the present invention can be carried out by performing a solid-state reaction using the above reaction formula.

[0127] First, to synthesize lanarkite, PbO powder and PbSO4 powder are uniformly mixed at a molar ratio of 1:1, put into an alumina crucible, then placed in a heating furnace, reacted at 725 °C for 24 hours. After the reaction is completed, it is pulverized and put into a vial for storage.

[0128] Next, to synthesize Cu3P, Cu powder and P powder are mixed at a composition ratio, placed in a reaction tube (quartz tube), sealed after forming a vacuum, reacted at 550 °C for 48 hours, and after the reaction is completed, taken out from the reaction tube, the ingot is pulverized, put into a vial, and stored.

[0129] Next, to obtain the ceramic compound according to the present invention, the synthesized ranalcite and Cu3P are uniformly mixed at a molar ratio of 1:1, put into a reaction tube, sealed after forming a vacuum, and reacted at 600 °C to 1000 °C for 5 to 40 hours (if it is less than this temperature range, sufficient reaction energy cannot be supplied, and if it exceeds this range, SO4 contained in ranalcite may be decomposed. Also, if it is less than this time range, a large amount of unreacted substances will exist, and even if it exceeds this range, the reaction has already ended and there may be no particular effect). After the reaction is completed, the sample taken out from the reaction tube is in the form of an ingot, and if necessary, this ingot can be processed or pulverized and stored.

[0130] The electrical properties and structural properties of the ceramic compound according to the present invention synthesized through a solid-state reaction based on the above reaction formula can be confirmed through FIGS. 31 and 32.

[0131] Referring to FIG. 31, the resistance of the electrical properties is obtained by processing the ingot of the solid-state reaction into a square shape and measuring the change in resistance due to the change in temperature (304K to 382K). The measurement method can use the same method as the previous measurement method of the electrical properties.

[0132] Overall, the largest transition is Tc_III at 377K (about 104 °C). Tc_I and Tc_II are not clearly visible, but when the temperature range is expanded, it can be seen that there are changes at 315K (about 42 °C) and 343K (about 70 °C). Here, it is judged that the Tc_III phase is the most, and the Tc_I phase and the Tc_II phase are partially mixed.

[0133] Also, referring to Fig. 32, it is an XRD analysis graph. The XRD pattern measured by pulverizing the ingot synthesized by the solid-phase reaction is shown in (a). To be comparable with the XRD data for the ceramic compound synthesized by the above-described vapor deposition, the result of matching using COD is shown in (b). A remarkable point is that the eulytite structure, which was not observed in the vapor deposition product, was observed as a by-product. The reason is considered to be that eulytite has a composition similar to 'LK99' in that phosphate groups and sulfate groups coexist. Also, it shows non-conductive properties, which is considered to be because it does not contain copper (Cu), which is a doping substance. Since it is an electrical insulator with a large energy gap, in order to have electrical conductivity, especially superconducting properties, substituents, dopants, and defects that can create new energy levels are required. Here, the reason it is an electrical insulator with a large energy gap is that apatite is originally an ionic compound with an overall oxidation number of zero. The properties of ionic compounds are originally transparent crystals (powders are white) or slightly colored electrical insulators due to a large energy gap. Since eulytite is also an ionic compound, it is an electrical insulator.

[0134] To investigate the volume occupied by each of the other by-products, volume% is calculated and shown in (a) (using MAUD, which is Rietveld software). The dotted line is the experimental value, and the solid line is the calculated value. The reason for examining the volume ratio is that when superconductivity and non-superconductivity are mixed, only when the ratio of the superconducting volume exceeds a certain critical point, the superconducting particles are electrically connected to each other (percolation), showing superconducting characteristics such as IV transition and RT transition. The ceramic compound synthesized by the solid-phase reaction according to the present invention shows superconducting electrical properties because the volume% of apatite occupies approximately half (48.9 volume%).

[0135] Example 1 Vapor Deposition Synthesis A of Chemical Formula 1 aB b (EO4) c X d In (EO4), A uses Pb, B uses Cu, E uses P, X uses S (Pb: DAEJUNG, EP, Cu: DAEJUNG, EP, S: DAEJUNG, EP, P: JUNSEI, EP), and 3 g of the total weight is weighed according to the molar ratio within the range where a is 0 to 10, b is 0 to 10, c is 0 to 6, and d is 0 to 4, placed in a quartz tube, and while maintaining a vacuum state of 10 -5 Torr, the quartz tube is placed in a furnace chamber, and vapor deposition is carried out while vaporizing at a reaction temperature of 550 °C to 2000 °C and a reaction time of 0.5 to 100 hours to synthesize the ceramic compound according to the present invention.

[0136] Example 2 Vapor Deposition Synthesis A of Chemical Formula 1 a B b (EO4) c X d In, A uses Pb, B uses Cu, E uses P, X uses S, and 3 g of the total weight is weighed according to the molar ratio within the range where a is 0 to 10, b is 0 to 10, c is 0 to 6, and d is 0 to 4, placed in a quartz tube, and after making it into a vacuum state of 10 -5 Torr and maintaining it for 20 minutes, then, with the total length of the tube being 15 cm, it is sealed using a torch, the quartz tube is placed in a furnace chamber, and reacted at a reaction temperature of 550 °C to 1100 °C and a reaction time of 10 to 100 hours to synthesize a ceramic precursor and used as a raw material for vapor deposition. Except for this, it is carried out in the same manner as in Example 1 to synthesize the ceramic compound according to the present invention.

[0137] Example 3 Vapor Deposition Synthesis A of Chemical Formula 1 a B b (EO4) c X d In, A uses Pb, B uses Cu, E uses P, X uses S, and 3 g of the total weight is weighed according to the molar ratio within the range where a is 0 to 10, b is 0 to 10, c is 0 to 6, and d is 0 to 4, placed in a quartz tube, and with a vacuum pump at 10 -5After bringing it to a vacuum state of Torr and maintaining it for 20 minutes, then, while making the total length of the tube 15 cm, it is sealed using a torch, the quartz tube is placed in a heating furnace chamber, and reacted at a reaction temperature of 550°C to 1100°C for a reaction time of 10 to 100 hours to synthesize a ceramic precursor. This is placed on a substrate as a raw material, arranged in a vacuum chamber, then placed on a heating part (tungsten boat), and 10 -5 While maintaining the vacuum at 10 Torr or less and liquefying while maintaining the temperature of the heating part at about 550°C to 900°C for about 1 to 5 minutes, then raising the temperature to 900°C to 2000°C to vaporize it, and depositing it on the surface of a high-purity glass plate arranged in the rising path of the gas to synthesize the ceramic compound according to the present invention.

[0138] Example 4 Solid-State Reaction Synthesis To synthesize lanarkite, PbO powder and PbSO4 powder are uniformly mixed at a molar ratio of 1:1, put into an alumina crucible, then put into a heating furnace, and reacted at 725°C for 24 hours. After the reaction is completed, it is pulverized. To synthesize Cu3P, Cu powder and P powder are mixed at a composition ratio, put into a reaction tube (quartz tube), sealed after forming a vacuum, and reacted at 550°C for 48 hours. After the reaction is completed, it is taken out from the reaction tube and the ingot is pulverized. The lanarkite and Cu3P are uniformly mixed at a molar ratio of 1:1, put into a reaction tube, sealed after forming a vacuum, and reacted at 600°C to 1000°C for 5 to 40 hours to synthesize the ceramic compound according to the present invention. The sample taken out from the reaction tube after the reaction is in the form of an ingot. Here, the materials used for the solid-state reaction were PbO (JUNSEI, GR), PbSO4 (KANTO, GR), Cu (DAEJUNG, EP), and P (JUNSEI, EP).

[0139] Example 5 Deposition Synthesis It was carried out in the same manner as in Example 3, except that the substance obtained through the solid-state reaction synthesis of Example 4 was used as a raw material.

[0140] Experimental Example 1 Hue and Microphotograph (Scanning Electron Microscope (SEM) Photograph) As shown in FIG. 1, for the ceramic compound according to Example 2, it can be seen that the region N close to the heat source S for heating the raw materials is white W, the far region F is black B, and the intermediate region M shows gray G.

[0141] Also, as shown in FIGS. 2 to 5, it can be seen that fine structures for white, black, and gray are uniformly formed at 50 μm.

[0142] In addition, FIGS. 34 and 35 respectively show SEM measurement photos for Example 3 and Example 5.

[0143] Experimental Example 2 Crystal Structure When measuring the ceramic compound according to Example 2 through a measuring equipment (Multi-Purpose X-ray Diffractometer, PHILIPS), as shown in FIG. 7, it can be seen that the structure 'LK99' of the ceramic compound of the present invention is different from the structure of apatite.

[0144] Experimental Example 3 Raman Measurement Raman spectroscopy was measured for Example 2 using a measuring equipment (Raman Spectrometer, NOST) and shown in FIG. 8. Referring to this, it can be confirmed that the ceramic compound of the present invention has a phosphate group.

[0145] Experimental Example 4 Measurement of Magnetic Susceptibility with Temperature Change The magnetic susceptibility for Example 2 was measured using a measuring equipment (SQUID-Vibration Sample Magnetometer, Quantum Design MPMS3) and shown in FIGS. 13 to 15. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting properties.

[0146] Experimental Example 5 Measurement of Magnetic Susceptibility with Magnetic Field Change The magnetic susceptibility for Example 2 was measured using a measuring equipment (SQUID-Vibration Sample Magnetometer, Quantum Design MPMS3), and the results are shown in FIGS. 16 to 18. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting properties.

[0147] Experimental Example 6 Measurement of I-V change The I-V with respect to the temperature change for Example 1 was measured using a measuring equipment (Power(voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: 4-terminal method (4-probe method)), and the results are shown in FIG. 33. Referring to this, it can be seen that there is a sharp change in the slope of the I-V change curve due to the temperature change, in other words, the voltage change appears depending on the + / - current direction, but in the vicinity of 0 (V), there appears a section where the current value is constant, and as described based on FIG. 12, it can be seen that it is a superconducting phenomenon.

[0148] Also, FIGS. 36 and 37 are graphs for Example 3 and Example 5, respectively, and it can be seen that they are superconducting phenomena.

[0149] Experimental Example 7 Measurement of IV due to temperature change The I-V with respect to the temperature change for Example 2 was measured using a measuring equipment (Power(voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: 4-terminal method (4-probe method)), and the results are shown in FIGS. 19 to 21. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting properties.

[0150] Also, the specific resistance value of a commercial copper foil (Cu foil) is about 10 -6 Ω·cm, and it can be seen that the resistance is even higher than that of the ceramic compound according to the present invention (showing a difference of about one order).

[0151] In addition, FIG. 38 is a graph for Example 4, showing superconducting characteristics due to temperature changes.

[0152] Experimental Example 8 Measurement of IV due to magnetic field changes For Example 2, the IV characteristics due to magnetic field changes were measured using measurement equipment (Power(voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: 4-probe method), and the results are shown in FIG. 22. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting characteristics.

[0153] Also, FIG. 39 is a graph for Example 4, showing superconducting characteristics due to magnetic field changes.

[0154] Experimental Example 9 Measurement of RT due to temperature changes For Example 2, the RT characteristics due to temperature changes were measured using measurement equipment (Power(voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: 4-probe method), and the results are shown in FIG. 23. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting characteristics.

[0155] In addition, FIG. 40 is a graph for Example 4, showing the measurement results of RT of a product by the solid-phase method in which the Tc_III region, which is the phase having the highest critical temperature, was mainly formed, showing a critical temperature exceeding -104°C.

[0156] Experimental Example 10 Component analysis of ceramic compounds in solid-state reaction For the component analysis of Example 4, measurements were made using SEM-EDX (measurement equipment: FE-SEM, EDX), and the results are shown in FIGS. 24 to 27. Looking at the micrographs (SEM), it can be seen that the surface shape is similar to that of Example 1. Looking at FIG. 28, it can be seen that the structure of the ceramic compound according to the present invention is LK99, which is different from the apatite structure.

[0157] Also, FIG. 41 is a table for Example 4.

[0158] Experimental Example 11 Measurement of Electrical Characteristics of Ceramic Compounds by Solid-State Reaction For Example 4, the ingot of the solid-state reaction was processed into a square shape, and the change in resistance due to the change in temperature (304K to 382K) was measured using measurement equipment (Power (voltage / current) Source KEITHLEY 228A, Sensitive Digital Voltmeter KEITHLEY 182, probe method: 4-probe method), and the results are shown in FIG. 29. Referring to this, it can be seen that the ceramic compound according to the present invention exhibits superconducting characteristics.

[0159] In addition, FIG. 42 is a photograph of an experiment in which the resistance of Example 4 was measured in real time, and the measured resistance shows a very low resistance of approximately 10 -12 ~10 -10 Ohmcm.

[0160] Experimental Example 12 Crystal Structure of Ceramic Compounds by Solid-State Reaction For Example 4, measurements were made through measurement equipment (Multi-Purpose X-ray Diffractometer, PHILIPS) for XRD analysis, and the results are shown in FIG. 30. Referring to this, it can be seen that the structure of the ceramic compound according to the present invention is LK99, which is different from the apatite structure.

Industrial Applicability

[0161] The present invention has been demonstrated in a partially filled SQW model and should be a very useful material in studying superconducting puzzles at room temperature. All evidence and explanations indicate that LK-99 is the first room-temperature and ambient-pressure superconductor, and it can be said that LK-99 has various application possibilities such as magnets, motors, cables, maglev trains, power cables, qubits for quantum computers, THz antennas, etc.

Claims

1. A superconducting ceramic compound, characterized by comprising a ceramic compound having a crystal structure of apatite represented by Chemical Formula 1. <Chemical Formula 1> A ａ B ｂ (EO ４ ) ｃ X ｄ A, E, and X are elements constituting an apatite mineral, B is a substituent and is an element having a d orbital, A contains Pb, B contains Cu, E contains P and S, X contains S or O, 0 < a < 10, 0 < b < 10, a + b = 10, c = 6, 0 < d ≤ 4.

2. The superconducting ceramic compound according to Claim 1, wherein the ceramic compound has a gray or black tint.

3. The superconducting ceramic compound according to Claim 1, wherein the magnetic susceptibility of the ceramic compound due to a change in temperature exhibits superconducting characteristics.

4. The superconducting ceramic compound according to Claim 1, wherein the magnetic susceptibility of the ceramic compound due to a change in magnetic field exhibits superconducting characteristics.

5. The superconducting ceramic compound according to Claim 1, wherein the current-voltage characteristics of the ceramic compound due to a change in temperature exhibit superconducting characteristics.

6. The superconducting ceramic compound according to Claim 1, wherein the current-voltage characteristics of the ceramic compound due to a change in magnetic field exhibit superconducting characteristics.

7. The superconducting ceramic compound according to Claim 1, wherein the resistance-temperature characteristics of the ceramic compound due to a change in temperature exhibit superconducting characteristics.

8. The superconducting ceramic compound according to Claim 1, wherein the ceramic compound contains Cu that enters between the vacant spaces in the crystal structure.

9. The superconducting ceramic compound according to Claim 1, wherein the ceramic compound is distributed within a thin film formed on a substrate.

10. The superconducting ceramic compound according to Claim 1, wherein the ceramic compound is in the form of an ingot or powder.

Images