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

Abstract

To provide a room-temperature atmospheric-pressure superconducting ceramic compound and a method for producing the same.SOLUTION: The present invention provides a room-temperature atmospheric-pressure superconducting ceramic compound and a method for producing the same that are characterized by comprising a ceramic compound represented by Chemical Formula 1: A10-xBx(PO4)6O (wherein A is Ca, Ba, Sr, Sn, or Pb; B is Cu, Cd, Zn, Mn, Fe, Ni, or Ag; and x is 0.1 to 2.0). According thereto, there is an effect of exhibiting superconducting properties at room temperature and atmospheric pressure.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a superconducting ceramic compound at room temperature and normal pressure and a method for producing the same, and more particularly to a superconducting ceramic compound that exhibits superconducting properties at room temperature and normal pressure and a method for producing the same. [Background technology]

[0002] The modern era has seen remarkable advances in electronic technology, so much so that it is now called the age of electricity and electronics. The fundamental aspect of this is, of course, the sufficient supply of electricity based on power generation, transmission, and distribution, which has led to the development of technologies for storing electricity, such as primary and secondary batteries, and wireless power transmission and reception, and is the driving force behind the remarkable development of the modern era.

[0003] However, the recent challenges of preparing alternative solutions to environmental and energy issues, as well as solving the problem of reduced efficiency caused by the increasing integration / density of semiconductors, have led to the need to search for new materials to replace / solve the problem that has fundamentally been solved by using existing low-resistivity materials such as copper and gold.

[0004] One field that attracted interest as an approach to this issue was the field of high-temperature superconductivity, and in 1986, Bednorz and Muller surprised the solid-state physics community by announcing a new class of superconducting materials with a critical temperature (Tc) higher than the critical temperature limit of the classical BCS theory [Bednorz, et al, ZPhys B 64, 189 (1986)].

[0005] These materials are ceramics consisting of copper oxide layers separated by buffer cations. In Bednorz and Mueller's original compound (LBCO), the buffer cations are lanthanum and barium. Inspired by their work, Paul Chu synthesized a similar material in which the buffer ions are yttrium and barium.

[0006] This material is YBCO, the first superconductor with a Tc exceeding the boiling point of liquid nitrogen (77 K) [Wu, et al, Phys Rev Lett 58, 908 (1987)].

[0007] In a similar groundbreaking report, the highest critical temperature increase is known to be 203.5 K for hydrogen sulfide at a pressure of 155 GPa. [Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system. Nature 525, 73 (2015)]

[0008] Related research using similar materials continued thereafter, and the critical temperature continued to rise. In 2020, a superconducting material with a critical temperature of 15°C, close to room temperature, was reported; however, this required an extremely high pressure of 267 GPa. As a result of repeated efforts to lower the pressure, in 2021, a material was reported that exhibited superconducting properties at approximately -5°C when subjected to a pressure of 186 GPa. However, it is believed that this method would be difficult to apply in real life (https: / / en.Wikipedia.org / wiki / Room-temperature_superconductor).

[0009] The reason is that, although it is true that there are high expectations in the academic world for room-temperature superconductors due to the experimental results of hydrogen sulfide systems and yttrium superhydrides, 267 GPa and 186 GPa are pressures equivalent to approximately 200,000 times atmospheric pressure (1 atm), and when converted to weight, they are equivalent to 1 cm 2 This adds up to more than 2,700 tons to an area of ​​1,000 m², and is considered to be almost impossible to use industrially in itself.

[0010] Therefore, it is necessary to develop superconducting materials that can be used not only at room temperature but also at normal pressure. Only materials that are not hydrogen sulfide or yttrium superhydride-based, in other words, that do not require high pressure, will have high applicability and be more widely available across industry.

[0011] In a previously filed invention, the inventors have disclosed a material containing a small amount of room temperature and pressure superconducting material with a critical temperature of 313K. Through analysis of magnetic properties and MAMMA, it was confirmed that the material contained a superconducting material, but because the amount contained was small, the electrical properties specific to superconductivity were insufficiently confirmed. Summary of the Invention [Problem to be solved by the invention]

[0012] 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 pressure.

[0013] A second technical problem to be solved by the present invention is to provide a method for producing a superconducting ceramic compound that exhibits superconducting properties at room temperature and normal pressure.

[0014] A third technical problem to be solved by the present invention is to provide a method for producing a superconducting ceramic compound in a solid state, which exhibits superconducting properties at room temperature and pressure. [Means for solving the problem]

[0015] In order to solve the first technical problem, the present invention provides a superconducting ceramic compound characterized by including a ceramic compound represented by Chemical Formula 1.

[0016] <Chemical formula 1> A 10-x B x (PO4)6O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

[0017] According to another embodiment of the present invention, B may be substituted at the A site of the formula 1.

[0018] According to another embodiment of the present invention, the position of another A may be changed by the B.

[0019] According to another embodiment of the present invention, the lattice structure of the ceramic compound may be modified by the substitution of B.

[0020] According to another embodiment of the present invention, a superconducting quantum well (SQW) may be formed between A and (PO4)6.

[0021] According to another embodiment of the present invention, the distance between the superconducting quantum wells (SQW) may be 3.7 Å to 6.5 Å.

[0022] According to another embodiment of the invention, tunneling may occur between the superconducting quantum wells (SQW).

[0023] According to another embodiment of the present invention, the substitution of B may increase strength and hardness and reduce the change in heat capacity.

[0024] Meanwhile, in order to solve the second technical problem, the present invention provides a method for producing a superconducting ceramic compound, which comprises a step of vapor-depositing and synthesizing a ceramic compound represented by Chemical Formula 1.

[0025] <Chemical formula 1> A 10-x B x (PO4)6O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

[0026] According to another embodiment of the present invention, the deposition may be performed at a reaction temperature of 550°C to 2000°C.

[0027] Also provided is a method for producing a superconducting ceramic compound, comprising the step of reacting ranarkite (Lanarkite (Pb2SO5=PbO·PbSO4)) with copper phosphide (Cu3P) to synthesize a ceramic compound represented by Chemical Formula 1.

[0028] <Chemical formula 1> A 10-x B x (PO4)6O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

[0029] According to another embodiment of the present invention, the temperature during the reaction may be 600°C to 1000°C.

[0030] According to another embodiment of the present invention, the ranalkite may be prepared by weighing PbO and PbSO4 according to the composition, mixing them and heating them.

[0031] According to another embodiment of the present invention, the synthesis of Cu3P may be carried out by weighing Cu and P according to the composition ratio, mixing them, and heating them.

[0032] Meanwhile, the present invention provides a superconducting ceramic compound produced by the above-mentioned production method.

[0033] According to another embodiment of the present invention, the ceramic compound may exhibit diamagnetic susceptibility depending on the temperature.

[0034] According to another embodiment of the present invention, the ceramic compound may exhibit diamagnetic or ferromagnetic susceptibility depending on the change in magnetic field.

[0035] According to another embodiment of the present invention, the ceramic compound may have a current-voltage characteristic with temperature that does not follow Ohm's law (V=I×R, where V: voltage, I: current, R: resistance) (V≠I×R).

[0036] According to another embodiment of the present invention, the ceramic compound may have a current-voltage characteristic with respect to a change in a magnetic field such that V=I×R or V≠I×R depending on the magnetic field.

[0037] According to another embodiment of the present invention, the resistance-temperature characteristic of the ceramic compound with respect to temperature may obey Ohm's law above a transition temperature.

[0038] According to another embodiment of the present invention, the heat capacity characteristics of the ceramic compound may not follow the law of heat capacity change according to the Debye model. [Effects of the Invention]

[0039] The ceramic compound and the method for producing the same according to the present invention have the effect of exhibiting superconducting properties at room temperature and normal pressure. [Brief explanation of the drawings]

[0040] [Figure 1-2] 1 is a schematic diagram of the structure of a ceramic compound according to the present invention, where A represents Pb and B represents Cu. FIG. 1 shows the structure and unit cell of the ceramic compound as viewed from the c-axis direction perpendicular to the ab-plane in a Cartesian coordinate system representing space. FIG. 2 is a diagram showing the structure of the unit cell of FIG. 1 formed along the c-axis perpendicular to the ab-plane. The interior of the solid-line box is the unit structure of the ceramic compound according to the present invention, and shows the position where a superconducting quantum well (SQW) is generated. [Figure 3] A (Pb(II) ion) shows a structure in which B (Cu(II) ion) is substituted for the position of polyhedral Pb(II), and together with this, a diagram schematically showing the volume reduction and stress generation due to the substituted copper ion in the ceramic compound of the present invention. [Figure 4]Figure 2 shows the band diagram in which a superconducting quantum well (SQW) is formed by structural distortion between Pb(I) and phosphate oxygen. [Figure 5] 1 is a photograph of an LK-99 sample according to the present invention, showing a dark grey (light black) color. [Figure 6-7] 1A and 1B are graphs showing the voltage versus applied current measured at 298K to 398K for the sample of Example 1, and the zero resistance, respectively, in which the exponent of the values ​​on the vertical axis of the graph is 10-9 (x10-9). [Figure 8-9] 10A and 10B are graphs showing the external magnetic field (H) dependence of the applied current and zero-field cooling for the sample of Example 2, respectively. [Figure 10-11] 10A and 10B are graphs showing the correlation between the critical current and the critical magnetic field and the correlation between the critical current and the critical temperature for the sample of Example 2, respectively. [Figure 12] 1 shows the results of an XRD experiment on the sample of Example 2. [Figure 13] 1 is a graph of the EPR signal of LK-99 according to the present invention. [Figure 14] 1 is a graph of the EPR signal obtained after measuring the IV of LK-99. [Figure 15] 1 is a graph showing Debye temperatures calculated from heat capacity data. [Figure 16] 1 is a heat capacity curve of LK-99 according to the present invention. [Figure 17-18] 10A and 10B are graphs showing the ferromagnetic behavior of the sample of Example 2 measured by SQUID in VSM mode at 300 K, respectively. [Figure 19] 1 is a graph showing the Meissner effect (near 0 Oe, <±100 Oe), ferromagnetic (<±500 Oe), and diamagnetic (>±500 Oe) behavior of the sample of Example 2 measured in a DC magnetic field at 100 K. [Figure 20] 1 is a graph showing an absorption signal in electron spin resonance measurement of the sample of Example 2. [Figure 21-22]Figure 21 shows magnetic levitation photographs of the sample of Example 2. When no current is supplied to the LK-99 sample, the diamagnetic properties are very small, so the magnetic levitation phenomenon is poor when the sample is simply placed on a magnet. Figure 22 shows that the increased Cooper pairs generated by the supplied current strengthen the diamagnetic properties, resulting in the magnetic levitation phenomenon. BEST MODE FOR CARRYING OUT THE INVENTION

[0041] The present invention will be described in detail below.

[0042] However, it should be noted that the technical terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention.

[0043] Furthermore, unless otherwise defined in the present invention, technical terms used in the present invention should be interpreted in a way that is commonly understood by a person of ordinary skill in the art to which the present invention pertains, and should not be interpreted in an overly comprehensive or narrow sense. If a technical term used in the present invention is an incorrect technical term that does not accurately express the idea of ​​the present invention, it should be replaced with a technical term that can be correctly understood by a person skilled in the art. General terms used in the present invention should be interpreted in accordance with dictionary definitions or the context, and should not be interpreted in an overly narrow sense. Singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "comprise" or "comprise" should not be interpreted as necessarily including all of the various components or steps described in the invention, but should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included. In describing the present invention, if it is determined that a detailed description of related prior art may obscure the gist of the present invention, such detailed description will be omitted.

[0044] The present invention further discloses the crystal structure of only a small amount of superconducting material that could not be disclosed in the previously filed invention.

[0045] The present invention has discovered a method for increasing the amount of superconducting material in the form of a thin film through vapor deposition (VD), and through further analysis, has confirmed the reaction mechanism and crystalline structure of the superconducting material. Based on this information, the present invention has been able to synthesize superconducting material in the form of an ingot or powder using a general solid-state reaction.

[0046] In addition, the various energy sources used for deposition are not limited to thermal chemical vapor deposition (CVD), but also include, without limitation, atomic layer deposition (ALD), sputtering, thermal evaporation, e-beam evaporation, molecular beam epitaxy (MBE), pulsed laser deposition (PLD), etc., as long as they can deposit the raw material.

[0047] The superconducting ceramic compound according to the present invention is characterized by including a ceramic compound represented by Chemical Formula 1.

[0048] <Chemical formula 1> A 10-x B x (PO4)6O, x=0.1~2.0 (A is Ca, Ba, Sr, Sn or Pb, and B is Cu, Cd, Zn, Mn, Fe, Ni or Ag)

[0049] The chemical formula 1 has a structural similarity to apatite, but has different physical properties and characteristics, so in this patent, this structure is distinguished and referred to as "LK-99."

[0050] Apatite is a mineral in which metals such as phosphate groups are bonded, and has long been used as a dye. While apatite is an electrical insulator with a large energy gap, the LK-99 structure of the present invention forms new energy levels in the compound through substitutions, dopants, and defects, making it an electrical conductor, particularly exhibiting superconducting properties.

[0051] In addition, in Chemical Formula 1, A may be a metal such as Ca, Ba, Sr, Sn, or Pb, which may be an s-block metal or a p-block metal, or may be Y, La, or Ce, which may be a lanthanide metal, or a combination thereof.

[0052] Furthermore, B is Cu, Cd, Zn, Mn, Fe, Ni, Ag, etc., and has the characteristics of a d-block metal. B is a type of substitution or dopant, and is an element with a d-orbital, which allows it to change from an electrical insulator to a conductor or superconductor.

[0053] It is preferable that x=0.1 to 2.0. If x is less than 0.1, the structure of the ceramic compound generates only a small amount of spatial distortion or stress between particles due to distortion, and therefore a superconducting quantum well (SQW) may not be formed. Conversely, if x exceeds 2.0, the compound may not be formed or an unstable lattice or other lattice forms may be formed.

[0054] 1 and 2 are schematic diagrams of the structure of the ceramic compound according to the present invention, where A represents Pb and B represents Cu. FIG. 1 shows the structure and unit cell of the ceramic compound as viewed from the c-axis direction perpendicular to the ab-plane in a Cartesian coordinate system representing space. FIG. 2 shows the unit cell of FIG. 1 formed along the c-axis perpendicular to the ab-plane. The interior of the solid-line box represents the unit structure of the ceramic compound according to the present invention, and also shows the position where a superconducting quantum well (SQW) is generated.

[0055] FIG. 3 shows a structure in which A (Pb(II) ion) is substituted with B (Cu(II) ion) at the position of polyhedral Pb(2), and also shows a schematic diagram of the volume reduction and stress generation due to the substituted copper ion in the ceramic compound according to the present invention. FIG. 4 is a band diagram showing the superconducting quantum well (SQW) of FIG. 2 formed by structural distortion between Pb(1) and phosphate oxygen.

[0056] In Chemical Formula 1, six As (Pb(1)) and channel oxygens (O) form a polyhedron structure, i.e., three As are arranged in a triangular shape in a plane, and three As are stacked in a triangular shape above and below them in a plane, with the triangles arranged alternately rather than overlapping, and phosphate ((PO4)6) is arranged adjacent to each As.

[0057] Such a polyhedral structure, for example, where A is Pb, is represented as an asymmetric polyhedron 6Pb(1)-O, which is continuous above and below within the unit cell, forming a polygonal or cylindrical pillar structure within the overall solid structure.

[0058] More specifically, six Pb(1) atoms are arranged in layers of three each, forming two layers, centered around four sites where channel oxygen (O) can exist, located in the center of a triangle made of Pb(1).

[0059] When the unit cells are continuous, the channel oxygen (O) occupies any one of the four sites, and when the six Pb(1)-O layers in the unit cell thus formed are connected in the c-axis direction, a cylindrical pillar structure is formed, and this structure is surrounded by a three-dimensional structure made of Pb(2)-O Pb.

[0060] In summary, the LK-99 of the present invention has an overall three-dimensional network structure, surrounded by an insulating tetrahedron PO4 network structure, and within the surrounded structure, asymmetric polyhedrons 6Pb(1)-O are arranged, and the asymmetric polyhedrons 6Pb(1)-O are characterized by two triangles (3Pb(1)) arranged in a vertically shifted manner.

[0061] Here, B (Cu) is substituted for A, but it is not the A (Pb(1)) that forms the polyhedron mentioned above that is substituted, but rather the four A (Pb(2)) arranged on the outer shell of the polygonal or cylindrical pillar structure are substituted and arranged, and are expressed as Pb(2) to distinguish them from the Pb(1) that forms the internal pillar structure.

[0062] That is, polyhedrons 4Pb(2) are arranged in the insulating tetrahedron PO4 network structure of LK-99, and copper ions (Cu 2+ ) has a structural feature in which approximately one of the four Pb(2) ions is replaced by a copper ion, and the position of the Pb(1) ions is slightly displaced from their original position (before substitution) by the replaced copper ions. As shown in Figure 3, the replaced copper ions cause volume shrinkage and stress in the insulating tetrahedron PO4 network structure, which in turn causes distortion of the arrangement of Pb(1) in the polygonal or cylindrical pillars inside. This can be understood as causing distortion at the interface between the insulating tetrahedron PO4 network structure and the polygonal or cylindrical pillars, resulting in the formation of a superconducting quantum well (SQW).

[0063] Such substitution of copper ions in LK-99 results in copper ions (Cu 2+ , 87pm) is lead ion (Pb 2+, 133 pm), resulting in a volume reduction of 0.48%, and the stress generated by this volume reduction may ultimately affect the onset of superconductivity.

[0064] Here, the copper ratio is determined based on XPS atomic % data and can be confirmed by the Debye model for heat capacity, which will be described in more detail below.

[0065] The XPS atomic percentage can be calculated by adding up the areas of the binding energy peaks of the corresponding atoms, dividing by the total number of electrons occupying the measured orbitals of each atom, and then multiplying by the relative sensitivity of the XPS measurement for that atom to calculate the amount or intensity of each atom. The relative amounts of Pb and Cu can be calculated to determine the copper ratio; based on the XPS measurement data, when the value of Pb is 10, the value of Cu can be calculated to be about 0.9.

[0066] The ceramic compound LK-99 of the present invention has a gray or black hue that contrasts with the ivory color of apatite (FIG. 5), and is a superconductor, unlike apatite, which is an insulator.

[0067] In addition, the ceramic compound according to the present invention is characterized in that the substitution of B results in a change in the arrangement position of A, which increases the strength and hardness of the ceramic and reduces the change in heat capacity. This is because the substitution of B (Cu 2+ ) is A(Pb 2+ ) and therefore causes an overall shrinkage in volume.

[0068] That is, the substitution of B deforms the molecular structure, restricting normal three-dimensional vibrational motion, thereby reducing the change in heat capacity.

[0069] When electrons move by tunneling between superconducting quantum wells (SQW) of the ceramic compound according to the present invention, the resistance value can become zero. As is well known, the Josephson effect is similar to the effect in which current flows by tunneling even when an insulator is interposed between superconductors.

[0070] The spacing between the superconducting quantum wells (SQWs) of LK-99 is 3.7 Å to 6.5 Å, which is believed to enable tunneling between the superconducting quantum wells. For this tunneling to be possible, electrons with opposite spins combine to form a Cooper pair. The Coulomb attraction between the Cooper pair electrons and the nuclei of the surrounding atoms is significantly reduced, allowing the Cooper pair electrons to easily pass through the barrier. Furthermore, the kinetic energy required for tunneling is thought to come from the kinetic energy resulting from the electron-electron interaction between the Cooper pair and the sum of the kinetic energies of the two electrons in the Cooper pair. This energy source is believed to enable tunneling between the SQWs.

[0071] The LK-99 of the present invention has an SQW between the internal pillar structure of Pb(1) and the external insulating tetrahedral PO4 network structure, so that the applied current is transmitted through the SQW existing in the cylindrical pillars through a tunneling process. Since LK-99 has partially filled SQW, the transmitted electrons are thought to undergo pairing, superconducting electron (Cooper-pair), condensation, etc.

[0072] On the other hand, the LK-99 according to the present invention exhibits superconductivity at room temperature and pressure. 2+ ) was not relieved but was transmitted to the interface of the cylindrical column.

[0073] That is, the Pb(I) atoms at the interface of the polygonal (or cylindrical) pillars occupy a structurally restricted space, and such interface atoms are substituted by B, e.g., copper ions (Cu 2+) and such deformation can be maintained even at room temperature and atmospheric pressure (without relaxation, where the deformation is released and the material returns to its original state), which is thought to be why SQW is generated and superconductivity is exhibited.

[0074] Meanwhile, the method for producing a ceramic compound according to the present invention is characterized by comprising a step of synthesizing a ceramic compound represented by Chemical Formula 1 by vapor deposition of raw materials.

[0075] <Chemical formula 1> A 10-x B x (PO4)6O, x=0.1~2.0 (A is Ca, Ba, Sr, Sn or Pb, and B is Cu, Cd, Zn, Mn, Fe, Ni or Ag)

[0076] In addition, the raw materials may be prepared by weighing out the materials of Formula 1 according to the molar ratio, and reacting them in a vacuum-controllable reaction vessel at a reaction temperature of 550°C to 2000°C for 1 to 100 hours to form a vapor phase deposition, thereby synthesizing a ceramic compound.

[0077] Furthermore, the raw materials can be pretreated to ensure that vapor phase deposition is carried out effectively, densely, and uniformly. Such pretreatment can be carried out by weighing out the materials of Chemical Formula 1 according to the molar ratio and reacting them in a vacuum-controllable reaction vessel at a reaction temperature of 550°C to 1100°C for a reaction time of 1 to 100 hours to prepare a pretreated ceramic precursor, which can be used as a deposition raw material.

[0078] In the present invention, the process temperature and process time of TVD (Thermal Vapor Deposition), which is one of the physical vapor deposition (PVD) methods, can be (1) 550°C to 1100°C and 1 to 100 hours in the case of a ceramic precursor, and (2) 550°C to 2000°C and 0.001 to 100 hours in the case of a vapor deposition process.

[0079] This is because ceramic precursors are primarily prepared by setting the reaction conditions at a relatively low temperature (550℃~1100℃) depending on the composition ratio so that the reaction occurs in a well-mixed solid solution state, which is then used as a deposition raw material.

[0080] If the heating temperature of the ceramic precursor is below 550°C, sufficient mixing may not occur, which may result in the desired reaction not occurring sufficiently, while if the heating temperature exceeds 1100°C, the high temperature may cause changes in composition, which may lead to other reactions that do not result in the desired composition, as well as wasted energy. The heating time should be 1 to 100 hours, but if the heating time is less than 1 hour, the reaction may not occur sufficiently, as is the case when the temperature is low, while if the heating time exceeds 100 hours, too much energy may be wasted.

[0081] The heating temperature for the physical vapor deposition process, including thermal evaporation, using such precursors can be between 550 and 2000°C. If it is below 550°C, the elements cannot be vaporized sufficiently, making it difficult to form a uniform compound. Conversely, if it exceeds 2000°C, it can be difficult to form a superconducting compound. The heating time required is between 0.001 and 100 hours. If it is less than 0.001 hour, sufficient vaporization is difficult, making the film so thin that deposition hardly occurs. Conversely, if it exceeds 100 hours, energy can be wasted after deposition is completed.

[0082] Another deposition process is chemical vapor deposition (CVD), in which a well-prepared sample (including pre-treated materials) is placed in a vacuum in a heating unit and an energy source is applied to raise the temperature, converting it into a gas phase. If the temperature is below 550°C, the material to be vaporized may not vaporize properly, while if heated to a temperature above 2000°C, the temperature of the deposition surface may rise excessively, preventing the desired deposition phase from being formed properly. The heating time is 0.001 to 100 hours; if it is less than 0.001 hour, sufficient vaporization may be difficult, resulting in a very thin film that is almost completely undeposited. Conversely, if it exceeds 100 hours, energy may be wasted after deposition is complete.

[0083] In the case of CVD (Chemical Vapor Deposition), the primary reaction in which lanarkite is formed is thought to be that PbS first evaporates and then receives oxygen from the substrate, as shown in Reaction Scheme 1.

[0084] <Reaction Scheme 1> 2PbS(s)+5 / 2O2(s, from substrate)→Pb2SO5(s)+S(g)↑

[0085] It can then be seen that Cu and P replace Pb and S, respectively, on the ranalkite (Pb2SO5=PbO·PbSO4) formed in this way, creating 'LK-99', the structure of the superconducting ceramic compound of the present invention.

[0086] This can be seen through the following inference: (1) Superconducting materials are formed in the region where ranalkite is present, (2) both Cu and P are detected in the region of superconducting materials, (3) among the compounds formed by Cu and P, the substance in the database (COD) is Cu3P, and (4) therefore, it is found that ranalkite and Cu3P react to produce 'LK-99', which is the structure of the superconducting material, which is the ceramic compound of the present invention. This can be summarized as Reaction Scheme 2 below.

[0087] <Reaction Scheme 2> L+Cu3P→LK-99 (L: Ranalkite (Pb2SO5=PbO·PbSO4))

[0088] The above reaction scheme is the reaction mechanism of the ceramic compound according to the present invention. Apatite does not have a sulfate group alone, but can have a phosphate group alone or a mixture of phosphate and sulfate groups. Ranalkite is a sulfate compound, but when it reacts with Cu3P, some or all of the sulfur is replaced with phosphorus to form phosphate groups.

[0089] Therefore, the ceramic compound according to the present invention can be synthesized by a solid-state reaction using the above reaction formula.

[0090] First, to synthesize ranalkite, PbO powder and PbSO4 powder were mixed uniformly in a 1:1 molar ratio, placed in an alumina crucible, and then placed in a heating furnace to react at 725°C for 24 hours. After the reaction was completed, the mixture was crushed and stored in a vial.

[0091] Next, to synthesize Cu3P, Cu powder and P powder are mixed in the composition ratio, placed in a reaction tube (quartz tube), vacuum formed, sealed, and reacted at 550°C for 48 hours. After the reaction is complete, the mixture is removed from the reaction tube and crushed into an ingot, which is then stored in a vial.

[0092] Next, to obtain the ceramic compound of the present invention, the synthesized ranalkite and CuP are uniformly mixed in a 1:1 molar ratio, placed in a reaction tube, vacuum formed, sealed, and reacted at 600°C to 1000°C for 5 to 40 hours (if the temperature is below this range, sufficient reaction energy will not be supplied, if this range is exceeded, the SO4 contained in the ranalkite may decompose, and if the time is below this range, many unreacted substances will remain, and if this range is exceeded, the reaction may have already ended and no particular effect will be obtained). After the reaction is completed, the sample removed from the reaction tube is in the form of an ingot, which can be processed or crushed and stored as necessary.

[0093] Example 1 - Vapor deposition synthesis A in Chemical Formula 1 10-x B x In (PO4)6O, A is Pb and B is Cu, so Pb in the chemical formula 2 10-x Cu x To prepare (PO4)6O (x = 0.1 to 2.0), weigh out a total of 3 g according to the molar ratio, place it in a quartz tube, and vacuum it for 10 minutes. -5 After evacuating to Torr, the tube is maintained for 20 minutes, and then the total length of the tube is adjusted to 15 cm, and the tube is sealed using a torch. The quartz tube is placed in a furnace chamber, and the reaction temperature is 550°C to 1100°C, and the reaction time is 10 to 100 hours to synthesize a ceramic precursor. This is placed on a substrate as a raw material, and then placed in a vacuum chamber, and then placed on a heating unit (tungsten boat), and the ceramic precursor is heated for 10 to 100 hours. -5 The vacuum was maintained at or below Torr, and the temperature of the heating section was maintained at about 550°C to 900°C for about 1 to 5 minutes to liquefy the mixture, and then the temperature was increased to 900°C to 2000°C to vaporize it. The mixture was then deposited on the surface of a high-purity glass plate placed in the ascending path of the gas, thereby synthesizing the ceramic compound according to the present invention.

[0094] Example 2 - Solid Phase Synthesis To synthesize ranarkite, PbO powder and PbSO4 powder were mixed uniformly in a molar ratio of 1:1, placed in an alumina crucible, and then placed in a heating furnace and reacted at 725°C for 24 hours. After the reaction was completed, the mixture was pulverized. To synthesize Cu3P, Cu powder and P powder were mixed in the composition ratio, placed in a reaction tube (quartz tube), vacuum formed, sealed, and reacted at 550°C for 48 hours. After the reaction was completed, the mixture was removed from the reaction tube and the ingot was pulverized. The ranarkite and Cu3P were mixed uniformly in a molar ratio of 1:1, placed in the reaction tube, and then pulverized. -5 After creating a vacuum of Torr, the tube was sealed and reacted at 925°C for 10 hours to synthesize the ceramic compound according to the present invention. After the reaction was completed, the sample was removed from the reaction tube in the form of an ingot. The materials used in the solid-state reaction were PbO (JUNSEI, GR), PbSO (KANTO, GR), Cu (DAEJUNG, EP), and P (JUNSEI, EP).

[0095] The samples obtained from the solid-state reaction were obtained in the form of dark gray solid ingots, which were slightly porous due to the influence of gas molecules escaping during the synthesis reaction. The size of the sample varied depending on the size of the reaction vessel and the reaction volume. Electrical resistance was measured by processing the ingots into thin rectangular plates, while XRD, SQUID, and EPR were measured on crushed powder, and XPS was measured on the powder pellets.

[0096] Experimental Example 1 - Measurement of electrical characteristics The electrical properties of the ingot obtained in Example 2, processed into a thin rectangular plate, were measured using a four-point probe with a 1.2 mm spacing. A Keithley 228A and a Keithley 182 were used as the voltage / current source and digital voltmeter, respectively. For precise temperature control and measurement, a custom-designed heating device was fabricated using an insulating aluminum mounting plate and a halogen lamp as the heat source. A custom-made program using LabView software was also used for the measurements. All instruments were connected to a GPIB interface. Temperature measurements were performed on a Keithley 2000 using a Fluke 80BK-DMM K-type thermocouple probe on the surface of the sample.

[0097] FIG. 6 is a graph of voltage versus applied current measured at 298K to 398K. -3 The measurement was performed in a vacuum of 10 Torr, with the DC polarity changed every time the temperature increased by 20 K. -6 ~10 -9 It is in the Ω·cm range.

[0098] The ceramic compound of the present invention exhibits a current-voltage characteristic according to a change in magnetic field that does not follow Ohm's law when the magnitude of the external magnetic field is 0 G, where there is almost no change in voltage compared to the supplied current and the maximum current decreases according to the magnitude of the external magnetic field. After that, once the maximum current amount is exceeded, the compound exhibits a current-voltage characteristic that follows Ohm's law.

[0099] In addition, the ceramic compound of the present invention exhibits resistance-temperature characteristics according to temperature changes, as the superconducting phase is destroyed by temperature, and as the temperature increases, the amount of current at which electrical resistance is zero decreases, and eventually the superconducting phase is destroyed, resulting in the current-voltage characteristics of Ohm's law.

[0100] Figure 7 shows the zero resistance of the LK-99 thin film, a new superconductor that meets the international standard for zero resistance (Y. Wang, Fundamental Elements of Applied Superconductivity in Electrical Engineering. (Wiley, 2013), J. W. E. Kin, Experimental Techniques for Low-Temperature Measurements. (Oxford University Press, New York, 2006)). The voltage measured while increasing or decreasing the applied current is in the range of 0.1 μV / cm, and the resistivity is 10 -10 ~10 -11 The occurrence of residual resistance, calculated in the order of Ω·cm, decreased with the thin film due to fewer grain boundaries.

[0101] It can be seen that the ceramic compound of the present invention exhibits superconducting properties in that the current-voltage characteristics with temperature change do not follow Ohm's law, and there is almost no change in voltage compared to the supplied current.

[0102] Experimental Example 2 - Measurement of magnetic properties The degree of magnetization of 45.814 mg of the finely ground sample of Example 2 was measured using a superconducting quantum interference device (SQUID) (settings: dc mode, scan length 30 mm, 10 scans per measurement, scan time 10 seconds). Zero-field cooling was performed by heating from 400 K to 200 K without an external magnetic field, then increasing the temperature from 200 K to 400 K in a 10 Oe magnetic field, and then cooling from 400 K to 200 K in a 10 Oe magnetic field.

[0103] Another magnetization measurement was performed in VSM mode at 300 K from -20,000 Oe to +20,000 Oe, and a third magnetization measurement was performed in dc mode with a scan length of 30 mm, 10 scans per measurement, and a scan time of 10 seconds.

[0104] Zero field cooling was performed by cooling from 300K to 100K without an external magnetic field, and then measurements were made at 100K from 0 to 3500 Oe, 3500 Oe to -3500 Oe, and -3500 Oe to 3500 Oe.

[0105] Figure 8 shows the dependence of the applied current on the external magnetic field (H). As can be seen in particular in Figure 9, the DC magnetization values ​​for zero-field cooling and field cooling at 10 Oe are still negative even at temperatures up to 400 K. These results indicate that the superconducting phase still exists up to 400 K at 10 Oe.

[0106] When the temperature rises above the critical temperature (Tc), a transition occurs in which the magnetic susceptibility value suddenly increases. This measurement method is called ZFC, and a method in which the temperature is lowered from a high temperature is called FC. When the temperature drops below the critical temperature (Tc), a transition occurs in which the resistance value suddenly decreases (theoretically becomes zero). However, the ceramic compound of the present invention can obtain the same data even if the temperature starts from a low temperature and rises to 400K or higher.

[0107] That is, when the magnetic susceptibility of the ceramic compound of the present invention is measured by cooling it to 200 K, then increasing the temperature to 400 K, and then measuring the direct current (DC) magnetic susceptibility, and then cooling it again from 400 K to 200 K under a magnetic field of 10 G, it is found that the compound exhibits a negative magnetic susceptibility, i.e., diamagnetic properties, which are characteristic of superconductors.

[0108] 10 and 11 show that the critical current values ​​are not yet 0 at 400 K and above 3000 Oe, and that the superconducting phase is maintained up to 400 K. Furthermore, even at currents of less than 7 mA, the temperature remains above 400 K. This indicates that a superconducting transition temperature below 400 K cannot be found. Therefore, it can be concluded that the critical temperature of LK-99 according to the present invention is above 400 K.

[0109] Experimental Example 3 - XRD Measurement A ground powder sample of Example 2 was prepared and measured using an XRD measurement device (Rigaku (SmartLab, Japan)), and the ground powder sample was pelletized and measured for XPS.

[0110] Figure 12 shows the XRD results for LK-99, which match the reference database (Crystallography Open Database (COD)). The original XRD data was processed without any further processing, with only the Kα2 strip processed. In other words, the X-ray wavelength used in XRD is not a single wavelength, but a mixture of two wavelengths, Kα1 and Kα2, and considering that the difference in energy between the two wavelengths is similar, it is technically difficult to separate them. A closer look at the XRD peaks reveals that even a single peak is split into two by Kα1 and Kα2. During data processing, because the intensity of Kα2 is about half that of Kα1, software was used to remove the portion due to Kα2, and only the peak due to Kα1 was considered.

[0111] The data obtained in this way showed results very similar to those of apatite in the reference database.

[0112] This result shows that the LK-99 according to the present invention is polycrystalline, its main peak is similar to the lead-apatite (AP) structure, and the impurity (Cu2S) is contained in a small amount.

[0113] The conventional crystal system of lead-apatite is hexagonal (P6 3 / m , 176), with cell parameters a = 9.865 Å and c = 7.431 Å, while the LK-99 of the present invention has parameters a = 9.843 Å and c = 7.428 Å, and is seen to be in a more contracted form than the conventional one (the volume reduction of 0.48% is due to the volume V = a 2 c sin(60°) is calculated by substituting the unit cell parameters of lead-apatite and the unit cell parameters of LK-99.

[0114] On the other hand, in order to clarify the area where the stress due to the volume reduction of the ceramic compound of the present invention ultimately affects, i.e., to determine the change in the position of Pb(1), one-dimensional electron density calculation along one crystal axis was performed by Fourier transform of the calculated structure factor.

[0115] The electron density was calculated along the z direction θ(c) using the following equation 1, with the (001) reflection intensity of the XRD data as the reference.

[0116] [Formula 1] JPEG2025176068000002.jpg14170

[0117] where l, F(00l), c, and z denote the order of the (00l) diffraction peak, the structure coefficient, the unit cell parameter of the c-axis, and the atomic coordinate along the z-axis, respectively.

[0118] Based on the (00l) and (h00) reflection intensities of the XRD data in Figure 12, the above formula was applied to calculate the electron density of Pb(1) along the z and x directions, ρ(c, rho c) and ρ(a, rho a).

[0119] The positions of the Pb(1) composing the inner cylindrical pillars are slightly shifted from their original positions due to the substitution of the copper ions inside or outside, and in the repeating triangular structure of the Pb(1) in the cylindrical pillars, the distance between Pb(1) in one layer decreases to 2.61815 Å, and in the next layer, the original distance of 3.03340 Å increases to 5.23476 Å, but the distance to the c-axis between the triangular layers of Pb(1) in LK-99 (3.7140 Å) remains almost unchanged from that of lead-apatite (3.7153 Å).

[0120] The analysis of XPS data showed that the bond energy (BE) between lead (Pb(2)) and phosphorus (Phosphor) did not change, but p3 / 2 and 2 p1 / 2The phosphorus splitting value of the tetrahedral PO4 network structure between Pb(1) and Pb(1) increased slightly from 0.68 eV to 0.69 eV, and the total oxygen BE increased significantly to 0.21 eV, 0.33 eV, and 0.56 eV, respectively. The BE value of Pb(1) decreased slightly by 0.03 eV. This indicates that the volume reduction caused by the substitution of copper ions resulted in a change in the position of Pb(1) and a change in the bond energy between the oxygen atoms adjacent to Pb(1).

[0121] [Table 1]

[0122] Table 1 above shows the bond energy between lead-apatite and LK-99.

[0123] Experimental Example 4 - Electron Paramagnetic Resonance (EPR) Spectroscopy EPR spectroscopy measurements were performed using a JES-FA200 ESR X-band spectrometer (Jeol, Japan) in the temperature range of 3.45 K to 295 K. The incident microwave power was 0.9980 mW, the receiver gain was 100, the sweep time was set to 1 min, the modulated magnetic field was 10 G at 100 KHz, and the swept external magnetic field was set to -100 to 9,900 Oe or 0 Oe to 10,000 Oe.

[0124] The crushed powder sample of Example 2 was placed in a sealed vacuum (5 × 10 -5 The tube was set in a 5 mm quartz tube (Wilmad Lab Glass, USA) at 1000 rpm (torr), and the sealed quartz tube was loaded into a cylinder cavity equipped with a liquid helium cooling (cryostat) system.

[0125] After the IV measurement, the sample for measuring the EPR signal was loaded with a part of the sample for which the electrical properties were measured, and the measurement was performed in a non-vacuum sealed state.

[0126] The LK-99 of the present invention can explain the superconducting phenomenon due to the formation of superconducting quantum wells through the results of EPR experiments. FIG. 13 is a graph showing the EPR signal of the LK-99 of the present invention, and FIG. 14 is a graph showing the EPR signal obtained after measuring the IV of LK-99. The following description will be made with reference to these graphs.

[0127] The EPR signals in Figure 13 are obtained from Si / SiGe, dry native DNA, and Mg 2+ The signal is identical to that of a heterojunction quantum well such as α-Fe2O3 doped with Pb(1), and is interpreted as the cyclotron resonance signal of the quantum well's two-dimensional electron gas (2-DEG), which is generated at the interface between Pb(1) and the phosphate in LK-99.

[0128] Furthermore, the ceramic compound of the present invention exhibited an EPR signal at 3000 Oe due to the substituted copper ions, which is similar to the superconducting properties reported at 0.3 K and 1 K in GaAs / AlGaAs and DNA 2-DEG systems, and to the superconducting properties of 2-DEG systems with heterojunction-like interface structures such as LaAlO3 / SrTiO3.

[0129] This confirms that the ceramic compound of the present invention generates a superconducting quantum well (SQW) between Pb(1) and oxygen of phosphate due to the structural distortion of the molecular structure, and allows us to predict the SQW band diagram shown in Figure 2.

[0130] Furthermore, the superconductivity of LK-99 is closely related to this superconducting quantum well (SQW), and other electrical properties of the SQW of LK-99 are thought to be related to the very low Fermi energy (-9.47 eV) of Pb(I) and the large band gap of the insulator (5-7 eV), which are thought to contribute to an increase in the oxygen BE, a strong polarization of the insulating layer, and a decrease in the BE of Pb(I), and are judged to contribute to a decrease in the Fermi energy of Pb(I).

[0131] On the other hand, the EPR in Figure 13 is a signal without current application, and the EPR in Figure 14 is a signal with current application. Compared to the former, the latter signal intensity was reduced overall, and the cyclotron resonance signal intensity was relatively reduced.

[0132] From the SQW perspective, this allows us to determine that LK-99 has a partially filled SQW because there is no charge storage to feed the SQW, but the EPR signal of LK-99 can be detected as a cyclotron resonance signal, whereas the cyclotron resonance signal cannot be detected if the SQW is fully filled.

[0133] However, absorption signals appear at very low temperatures and in external magnetic fields below 1000 Oe, as has been observed in YBCO and Bi2212 (R. Janes, RS Liu, PP Edwards, AD Stevens, MCR Symons, Magnetic-Field Dependent Microwave-Absorption in High-Tc Superconducting Cuprates. J Chem Soc Faraday T87, 1209-1215 (1991), M. Puri et al., Microwave-Absorption Characterization of the Yba2Cu3O7-Delta High-Temperature Superconductor Prepared by Different Sintering and Oxygen Annealing Times. J Chem Soc Faraday T87, 167-174 (1991)). The signals in external magnetic fields below 1000 Oe can be interpreted as signals due to superconducting electrons.

[0134] Experimental Example 5 - Heat Capacity Measurement The heat capacity was measured from 5 K to 400 K using a Physical Property Measurement System (PPMS, Quantum Design, USA) with 65.26 mg of the sample from Example 2, and the measured data (raw data) was calibrated based on the heat capacity of CuS bulk and nanosheet, which were contained in small amounts as impurities.

[0135] FIG. 15 is a graph showing the Debye temperature calculated from the heat capacity data, and FIG. 16 is a heat capacity curve for LK-99 according to the present invention.

[0136] The Debye temperature is calculated by the following Debye heat capacity formula (Equation 2): 10-x Cu x Calculations were made based on the heat capacity data using the formula (PO4)6O (x=1).

[0137] [Formula 2] JPEG2025176068000004.jpg13170

[0138] where Cv is the heat capacity, r is the number of atoms per molecule, N is the number of molecules, k is the Boltzmann constant, T is the measurement temperature, θ is the Debye temperature, x=θ / T, and e is a natural constant.

[0139] As shown in FIG. 15, the Debye temperature of the LK-99 according to the present invention changes continuously from about 184 K to 1300 K, and the transition temperature (Tc) cannot be calculated using the conventional electron-phonon prediction model.

[0140] In other words, the Debye model is a model that handles the specific heat of a crystal via phonons, and since the ceramic compound of the present invention cannot be interpreted by this predictive model, it is determined that it is difficult to apply the electron-phonon model.

[0141] The heat capacity characteristics of the ceramic compound of the present invention do not show any change in the second-order phase transition characteristics that general superconductors show in the temperature range from 5K to 400K, and do not follow the law of heat capacity change according to the Debye model. Therefore, it can be seen that the ceramic compound is a material that exhibits heat capacity characteristics that reflect the internal structural changes of the ceramic compound, and exhibits the heat capacity characteristics of a room-temperature, normal-pressure superconductor.

[0142] As can be seen from Figure 16, the blue curve (Debye temperature = 280K) is the heat capacity calculated based on the Debye temperature of typical apatite, which is 280K, while the red curve (Debye temperature = 184.56K) is the heat capacity calculated based on the Debye temperature of LK-99 at a low temperature (5K) (184.56K). This shows that the heat capacity curve of LK-99 (black curve) does not apply because the normal vibration mode is restricted by the substitution of copper ions in the network portion, which is characteristic of the molecular structure of LK-99. This indicates that the structure is distorted due to the substitution of copper ions.

[0143] Experimental Example 6 - Measurement of magnetic susceptibility The magnetic susceptibility was measured in VSM mode at 300 K in the range of -20,000 G to +20,000 G using a 45.814 mg sample, using a Superconducting Quantum Interference Device (SQUID) or a Magnetic Property Measurement System (MPMS, Quantum Design, USA).

[0144] As shown in Figures 17 and 18, LK-99 according to the present invention exhibits ferromagnetic behavior at 300 K when measured in VSM mode with a SQUID (Figure 18 is obtained by correcting Figure 17 to reflect molecular diamagnetism).

[0145] Experimental Example 7 - Measurement of magnetic susceptibility The magnetic susceptibility was measured in DC mode at 100 K in the range of -3,500 G to +3,500 G using a superconducting quantum interference device and a sample of 45.814 mg.

[0146] FIG. 19 shows the Meissner effect (near 0 Oe, <±100 Oe), ferromagnetic (<±500 Oe), and diamagnetic (>±500 Oe) behavior measured in a DC magnetic field at 100 K.

[0147] That is, the ceramic compound of the present invention exhibits diamagnetism in the low magnetic field range (0 to ±50 G) in terms of magnetic susceptibility due to changes in the magnetic field, then exhibits ferromagnetic properties in the magnetic field range of ±50 G or more to ±500 G, and then again exhibits diamagnetism (molecular diamagnetism) in the magnetic field range of ±500 G to ±3500 G.

[0148] Mg 2+ Quantum wells with two-dimensional electron gas (2-DEG) systems, such as α-Fe2O3 doped with α-Fe and natural DNA, exhibit antiferromagnetic or ferromagnetic behavior, and the superconductivity of GaAs / AlGaAs systems and DNA 2-DEG systems has been reported to be 0.3 K and 1 K, respectively. Superconductors with interface structures such as heterojunctions of 2-DEG systems, such as LaAlO3 / SrTiO3, also exhibit both superconductivity and magnetism. LK-99 according to the present invention is also considered to be a system in which both ferromagnetic properties and superconductivity are exhibited.

[0149] Experimental Example 8 - Electron Paramagnetic Resonance (EPR) Spectroscopy Measurement The EPR signal was detected by applying a 1 mW microwave (~9.4 GHz) with a 100 KHz AC magnetic field modulation and passing a current of 200 mA to 100 mA through the sample at 0 G.

[0150] When the amount of current supplied to LK-99 is increased and measured with an electron spin resonator at 0G, an absorption signal appears as shown in Figure 20. It can be confirmed that the more current is supplied, the larger the absorption signal becomes.

[0151] Absorption of microwaves at 0 G is a known property of superconductors, so the increasing signal measured at 0 G with a fixed magnetic field can be interpreted as the generation of more Cooper pairs, which indicates superconductivity.

[0152] Therefore, this can be interpreted as electrons from the current supplied by the superconducting quantum well system of LK-99 being converted into superconducting electrons, resulting in even more absorption.

[0153] Experimental Example 9 - Adjustable Magnetic Levitation Measurement An electric wire was connected to the sample of Example 2, and the sample was placed on a magnet. The magnetic levitation phenomenon that occurred when no current was passed and when a current was passed was filmed as a video.

[0154] Figure 21 shows that when no current is supplied to the LK-99 sample, the diamagnetic properties are very small, so the magnetic levitation phenomenon is not good when it is simply placed on a magnet. Figure 22 shows that the diamagnetic properties are strengthened by the increased number of Cooper pairs generated by the supplied current, and the magnetic levitation phenomenon appears.

[0155] As a result, the LK-99 of the present invention exhibits superconductivity at room temperature and ambient pressure due to the inherent structure of LK-99, which is Pb(2) 2+ Cu ions 2+ This is because the stress generated by the replacement was not eliminated but was simultaneously properly transferred to the interface of the cylindrical column.

[0156] That is, the Pb(I) atoms at the interface of the cylindrical pillars of LK-99 occupy structurally restricted spaces, and these atoms are located in the Cu 2+ It is entirely affected by the stress and deformation generated by the ions, and therefore, SQWs can be created at the interface with phosphate with an appropriate amount of strain at room temperature and ambient pressure without relaxation.

[0157] From this perspective, in CuO and Fe-based superconductor systems, the relaxation process cannot be restricted by structural freedom, so the stress due to volume contraction caused by temperature and pressure is relaxed and eliminated, and therefore, an appropriate temperature or pressure is required to restrict structural freedom and achieve the creation of SQW. [Industrial Applicability]

[0158] This invention has been demonstrated in a partially filled SQW model, making it a very useful material for studying the superconductivity puzzle at room temperature. All evidence and explanations indicate that LK-99 is the first room temperature and ambient pressure superconductor. LK-99 has a wide range of potential applications, including magnets, motors, cables, magnetic levitation trains, power cables, quantum computer qubits, and THz antennas.

Claims

1. A superconducting ceramic compound comprising a ceramic compound represented by Chemical Formula 1. <Chemical formula 1> A １０－ｘ B ｘ (PO ４ ) ６ O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

2. 2. The superconducting ceramic compound according to claim 1, wherein B is substituted at the A site of the formula (1).

3. 3. The superconducting ceramic compound according to claim 2, wherein the B replaces the position of another A.

4. 3. The superconducting ceramic compound according to claim 2, wherein the lattice structure of the ceramic compound is modified by the substitution of B.

5. The A and (PO ４ ) ６ 3. The superconducting ceramic compound of claim 2, wherein a superconducting quantum well (SQW) is formed between the

6. 6. The superconducting ceramic compound according to claim 5, wherein the distance between the superconducting quantum wells (SQW) is 3.7 Å to 6.5 Å.

7. 6. The superconducting ceramic compound of claim 5, wherein tunneling occurs between the superconducting quantum wells (SQW).

8. 3. The superconducting ceramic compound according to claim 2, wherein the change in heat capacity is reduced by the substitution of B.

9. A method for producing a superconducting ceramic compound, comprising the step of vapor-depositing and synthesizing a ceramic compound represented by Chemical Formula 1. <Chemical formula 1> A １０－ｘ B ｘ (PO ４ ) ６ O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

10. 10. The method for manufacturing a superconducting ceramic compound according to claim 9, wherein the deposition is carried out at a reaction temperature of 550 to 2000°C.

11. Lanarkite (L, Lanarkite (Pb ２ SO ５ = PbO.PbSO ４ ) and copper phosphide (Cu ３ P) to synthesize a ceramic compound represented by Chemical Formula 1. <Chemical formula 1> A １０－ｘ B ｘ (PO ４ ) ６ O (A is Ca, Ba, Sr, Sn or Pb, B is Cu, Cd, Zn, Mn, Fe, Ni or Ag, and x is 0.1 to 2.0)

12. 12. The method for producing a superconducting ceramic compound according to claim 11, wherein the reaction temperature is 600 to 1000°C.

13. The ranalkite is PbO and PbSO ４ 12. A method for producing a superconducting ceramic compound according to claim 11, characterized in that the above ingredients are weighed out according to the composition, mixed, and heated.

14. The Cu ３ 12. The method for producing a superconducting ceramic compound according to claim 11, wherein the synthesis of P is carried out by weighing Cu and P according to a composition ratio, mixing them, and heating them.

15. A superconducting ceramic compound produced by the method according to any one of claims 9 to 14.

16. The superconducting ceramic compound according to claim 15, wherein the ceramic compound exhibits diamagnetic susceptibility depending on the temperature.

17. The superconducting ceramic compound according to claim 12, wherein the ceramic compound exhibits diamagnetic or ferromagnetic susceptibility depending on the change in magnetic field.

18. 13. The superconducting ceramic compound according to claim 12, wherein the ceramic compound has a current-voltage characteristic with respect to a change in temperature that satisfies V≠I×R (V: voltage, I: current, R: resistance).

19. 13. The superconducting ceramic compound according to claim 12, wherein the ceramic compound has a current-voltage characteristic that V=I×R or V≠I×R depending on the magnetic field.

20. 13. The superconducting ceramic compound according to claim 12, wherein the resistance-temperature characteristic of the ceramic compound with respect to temperature changes obeys Ohm's law above a transition temperature.

21. 13. The superconducting ceramic compound according to claim 12, wherein the heat capacity characteristics of the ceramic compound do not follow the law of heat capacity change according to the Debye model.

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