Apatite-based compound, conductive ceramic material comprising apatite-based compound, and method for manufacturing same

Abstract

Provided is a method for manufacturing a conductive ceramic material comprising an apatite-based compound. The method comprises: placing raw materials in a vacuum tube and sealing the vacuum tube; heating the vacuum tube to synthesize an apatite-based compound from the raw materials; separating a product including the synthesized apatite-based compound from the vacuum tube; and heating the product to degas residual sulfur. The raw materials used include PbO and PbSO4 as main lead sources, Cu as a main copper source, and P as a main phosphorus source. Furthermore, the apatite-based compound has a lead phosphate apatite (Pb10(PO4)6O) crystal structure and includes copper and sulfur that partially substitute for lead and phosphorus within the crystal structure, respectively.

Description

Apatite-based compound, conductive ceramic material having an apatite-based compound, and a method for manufacturing the same

[0001] The present invention relates to a conductive ceramic material and a method for manufacturing the same, and more specifically, to a conductive ceramic material having an apatite-based compound and a method for manufacturing the same.

[0002] Metallic materials such as copper, gold, and silver are widely used as electrical conductors in many fields, including the electrical and electronic sectors. In particular, copper is used significantly more than gold and silver because it has low resistivity and is relatively inexpensive.

[0003] However, metals such as copper are difficult to use alone due to their tendency to oxidize easily in air, requiring various surface treatment methods, such as coatings or cladding agents, to protect the surface. Furthermore, since metals have a relatively high coefficient of thermal expansion, measures are required to address thermal expansion issues caused by heat generation in environments with large temperature differences or during prolonged use.

[0004] To overcome the disadvantages of metals, research is being conducted on conductive ceramics with relatively small coefficients of thermal expansion. Since ceramic materials possess thermal stability and chemical durability, they can be used in various environments. Furthermore, conductive ceramic materials can be utilized for power generation, conversion, and transmission, as well as for nano-scale wiring resulting from high integration. They can also be applied to diverse applications requiring solutions to heat generation caused by resistance during electrode reactions in water and corrosion.

[0005] Patent document (10-2024-0028724) discloses an apatite-based ceramic compound synthesized by the reaction of lanarkite (Pb2SO5) and Cu3P. The ceramic material prepared by a solid-state reaction using the above raw materials contains Cu within the material. 2-xThere is a problem with the significantly low purity of apatite-based compounds due to the presence of large amounts of crystalline impurities such as S and PbS. Since these crystalline impurities are difficult to separate from ceramic materials, technology is required to prevent the formation of impurities during the synthesis stage and to increase the purity of apatite-based compounds.

[0006] The problem that the present invention aims to solve is to provide a new manufacturing method capable of increasing the purity of apatite-based compounds in synthesized ceramic materials and a conductive ceramic material manufactured thereby.

[0007] Another problem that the present invention aims to solve is to provide a conductive ceramic material containing an apatite-based compound in high purity.

[0008] Another problem that the present invention aims to solve is to provide an apatite-based compound suitable for conductive ceramic materials.

[0009] According to one embodiment of the present invention, a method for manufacturing a conductive ceramic material comprising an apatite-based compound is provided. The method comprises placing a raw material into a vacuum tube and sealing it, heating the vacuum tube to synthesize an apatite-based compound from the raw material, separating a product containing the synthesized apatite-based compound from the vacuum tube, and heating the product to degasify residual sulfur. As for the raw material, the main raw material for lead comprises PbO and PbSO4, the main raw material for copper comprises Cu, and the main raw material for phosphorus comprises P. Furthermore, the apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and contains copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure.

[0010] In one embodiment, the molar ratio of the raw materials is (PbO: PbSO4: Cu: CuSO4: P) = ((4-x): (6-v): x: v: (6-y)), where x and y are 0 <x<4, 0≤v≤6, 및 0<y<3일 수 있다.

[0011] In addition, the conductive ceramic material may contain 50 wt% or more of the apatite-based compound relative to the total weight of the entire crystalline compound including the apatite-based compound.

[0012] Meanwhile, Cu in the above conductive ceramic material 2-x The S crystalline compound may be less than 1 wt% of the total weight of the crystalline compounds. If the crystalline compound is less than 1 wt%, it is generally not detected by XRD. In this embodiment, Cu 2-x S crystal-based compounds may not be present at all in the conductive ceramic material, or may be contained in trace amounts; however, even if present, the amount is so small that it cannot be detected by XRD.

[0013] According to one embodiment of the present invention, a conductive ceramic material comprising an apatite-based compound is provided. The conductive ceramic material comprises an apatite-based compound and a crystal system compound different from the apatite-based compound, wherein the apatite-based compound is lead phosphate apatite (Pb 10 (PO4)6O) having a crystal structure, containing copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure, and containing 50 wt% or more of the apatite compound relative to the total weight of the total crystal system compound containing the apatite compound.

[0014] The conductive ceramic material may contain 70 wt% or more, further 90 wt% or more, and further 95 wt% or more of the apatite-based compound based on the total weight of the entire crystalline compound including the apatite-based compound.

[0015] In one embodiment, the conductive ceramic material may be in powder form.

[0016] In one embodiment, the total number of moles of phosphorus contained in the conductive ceramic material may be greater than the total number of moles of sulfur. Furthermore, the total number of moles of phosphorus in the apatite-based compound may be greater than the total number of moles of sulfur.

[0017] Meanwhile, the crystal structure of the apatite-based compound has channels formed by the arrangement of metal elements in the c-axis direction, and the apatite-based compound may further include sulfur disposed within the channels. In one embodiment, the apatite-based compound may include sulfur and oxygen together within the channels.

[0018] In one embodiment, the apatite-based compound may be represented by the following chemical formula 1.

[0019] (Chemical Formula 1)

[0020] Pb 10-x-v Cu (x+v) (PO4) 6-y (SO4) y O z-w S w (However, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z).

[0021] In one embodiment, the content of copper sulfide may be less than 1 wt% relative to the total weight of the entire crystalline compound including the apatite-based compound.

[0022] In one embodiment, the content of lead sulfide may be less than 4 wt% with respect to the total weight of the entire crystalline compound including the apatite-based compound.

[0023] Cu relative to the total weight of the entire crystalline compound containing the above apatite-based compound 2-x The content of S crystal system compounds may be less than 1 wt%.

[0024] According to one embodiment of the present invention, a conductive ceramic material comprising an apatite-based compound is provided. The conductive ceramic material comprises an apatite-based compound and a crystal system compound different from the apatite-based compound, wherein the apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and contains copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure. Furthermore, the total moles of phosphorus contained in the conductive ceramic material are greater than the total moles of sulfur, and regarding the total weight of the entire crystal system compound including the apatite-based compound, Cu 2-x The content of S crystal system compounds is less than 1 wt%.

[0025] In one embodiment, the total number of moles of phosphorus in the apatite-based compound may be greater than the total number of moles of sulfur.

[0026] In one embodiment, the crystal structure of the apatite-based compound has channels formed by the arrangement of metal elements in the c-axis direction, and the apatite-based compound may further include sulfur disposed within the channels.

[0027] According to one embodiment of the present invention, an apatite-based compound is provided. The apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and contains copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure, and the total moles of phosphorus contained in the compound are greater than the total moles of sulfur.

[0028] The above apatite-based compound has a crystal structure in which channels are formed by the arrangement of metal elements in the c-axis direction, and may further include sulfur disposed within the channels.

[0029] In one embodiment, the apatite-based compound is Pb 10-x-v Cu (x+v) (PO4)6-y (SO4) y O z-w S w (However, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z)로 표시될 수 있다.

[0030] According to embodiments of the present invention, a conductive ceramic material containing an apatite-based compound in high purity can be provided by reducing the content of impurities such as copper sulfide or lead sulfide. Furthermore, an apatite-based compound suitable for a conductive ceramic material can be provided.

[0031] Figure 1a shows the crystal structure of lead phosphate apatite viewed along the c-axis.

[0032] Figure 1b is an enlarged view of a part of Figure 1a.

[0033] Figure 1c is a perspective view of a portion of the crystal structure of lead phosphate apatite.

[0034] FIG. 2 shows a schematic crystal structure for explaining an apatite-based compound containing copper and sulfur according to one embodiment of the present invention.

[0035] Figure 3 is a schematic perspective view illustrating the channels of the apatite crystal structure.

[0036] FIG. 4 is a schematic cross-sectional view illustrating a vacuum tube used to manufacture a conductive ceramic material according to one embodiment of the present invention.

[0037] FIG. 5 is a schematic cross-sectional view illustrating a degassing device used to manufacture a conductive ceramic material according to one embodiment of the present invention.

[0038] Figure 6 is an XRD graph of the conductive ceramic material of Comparative Example 1 containing an apatite-based compound manufactured according to the prior art.

[0039] Figure 7 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0040] FIG. 8 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 2 of the present invention.

[0041] Figure 9 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 3 of the present invention.

[0042] Figure 10 is an XRD graph of a ceramic material according to Comparative Example 2.

[0043] Figure 11 is an XRD graph of a ceramic material according to Comparative Example 3.

[0044] FIG. 12 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 4 of the present invention.

[0045] FIG. 13 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 5 of the present invention.

[0046] FIG. 14 is an SEM image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0047] FIG. 15 is an SEM-EDS image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0048] FIG. 16 is a STEM image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0049] Figure 17 is a SAED photograph of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0050] FIG. 18 shows a wide-scan XPS spectrum of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0051] FIGS. 19 to 23 show the narrow scan XPS spectra of a conductive ceramic material containing an apatite-based compound according to Example 1.

[0052] FIG. 24 is an IV graph illustrating the electrical properties of a conductive ceramic material manufactured according to the present invention.

[0053] FIG. 25 is a current-temperature graph to explain the heating characteristics of a conductive ceramic material manufactured according to the present invention.

[0054] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments described below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. Furthermore, in the drawings, the width, length, thickness, etc., of components may be exaggerated for convenience. Throughout the specification, the same reference numerals indicate the same components.

[0055] FIG. 1a shows the crystal structure of lead phosphate apatite (LPA) viewed along the c-axis, FIG. 1b is an enlarged view of a portion of FIG. 1a, and FIG. 1c is a perspective view of a portion of the crystal structure of lead phosphate apatite. Here, FIG. 1b and FIG. 1c each show two unit cells superimposed in the direction of the c-axis.

[0056] Referring to FIGS. 1a, 1b, and 1c, the crystal structure of lead phosphate apatite consists of lead (Pb), phosphorus (P), and oxygen (O). Phosphorus is located within a tetrahedron surrounded by four oxygen atoms. Lead has two different sites within the crystal structure. The first site (Pb(I)) is arranged alternately along the corners of the unit cell in the c-axis direction, forming a triangle, and the second site (Pb(II)) is located within the region surrounded by the corners of the unit cell. As the lead atoms located in the second site are arranged in the c-axis direction while forming a triangle, c-axis channels are formed at the four vertices of the unit cell, as shown in FIG. 1b.

[0057] Oxygen also has two different sites: the first site (O(I)) is positioned around phosphorus to form a tetrahedron, and the second site (O(II)) is located within a channel formed by lead. FIG. 1c illustrates that one oxygen is located at each of the four corners parallel to the c-axis direction, and the sites where these oxygens are located correspond to the second site (O(II)). For convenience of explanation, the oxygen in the second site (O(II)) is also referred to as "channel oxygen" below. FIG. 1c illustrates one channel oxygen at each corner, and there are four sites where channel oxygen can be located at each corner within the unit cell. FIG. 1c is a superposition of two unit cells, and in the drawing of FIG. 1c, there are eight sites where channel oxygen can be located at each corner.

[0058] Lead phosphate apatite is known to be non-conductive, but it can be modified to be conductive by doping it with other elements. Lead phosphate apatite modified to be conductive in this way is referred to as Modified Lead Apatite (MLA). In particular, the present invention relates to lead phosphate apatite modified to be conductive using chalcogen and metal elements, and is referred to as Modified Apatite by Chalcogen and Metal (MACAM). Specifically, the present invention uses sulfur as the chalcogen element and copper as the metal element, and the structure of MACAM according to the present invention will be explained with reference to FIGS. 2 and 3.

[0059] FIG. 2 shows a schematic crystal structure for explaining an apatite-based compound containing copper and sulfur according to one embodiment of the present invention, and FIG. 3 is a schematic perspective view for explaining the channels of the apatite crystal structure. Here, FIG. 2 shows the crystal structure viewed in the c-axis direction.

[0060] Referring to FIGS. 2 and 3, copper can substitute lead at the first site (P(I)) and / or the second site (P(II)). Depending on the site where copper substitutes lead, it is designated as the first site (Cu(I)) and the second site (Cu(II)) of copper. Meanwhile, sulfur can occupy the sites of phosphorus and oxygen. In particular, sulfur can substitute the oxygen at the second site (O(II)), i.e., the channel oxygen. Among the sites where sulfur is located, the site corresponding to the phosphorus site is designated as the first site (S(I)), and the site corresponding to the channel oxygen is designated as the second site (S(II)). The sulfur at the second site can be referred to as channel sulfur.

[0061] The copper and / or lead in the first position form a triangle, and multiple triangles are arranged along the c-axis direction. Channels are formed by the arrangement of these metal elements, as indicated by the thick arrows in FIG. 3. The channels are formed along the four corners of the unit cell.

[0062] The apatite-based compound according to the present invention exhibits conductivity by having copper and sulfur substitute for lead and phosphorus. Free charges are generated within the compound by the substitution of copper and sulfur, and conductivity is expected to be produced by these free charges. It is thought that the generated charges will move through channels created by lead and copper. These channels are formed unidirectionally in the c-axis direction and have a one-dimensional shape, but since they have a cross-sectional area, they can be referred to as having a pseudo-1 dimension shape. The energy transfer direction of the charges flowing through the channels may interact in the cross-sectional direction within the channels, but the direction of transfer of the total mechanical energy will generally be in the length direction of the channels, the c-axis direction.

[0063] In the case of manufacturing apatite-based compounds by solid-state reaction according to the prior art, lanakite (Pb2SO5) and Cu3P were mixed as raw materials in a 1:1 ratio and fired in a quartz vacuum tube to produce a ceramic material containing an apatite-based compound. However, the ceramic material manufactured by the prior art contains copper sulfide, in particular, Cu 2-x It contains S impurities in an amount of about 30% or more of the total weight of the total crystal system compounds, and also contains other impurities such as PbS. These impurities are inevitably generated by the raw materials. Consequently, the amount of apatite-based compounds in the ceramic material is relatively small, and furthermore, it is difficult to accurately determine the composition of the apatite-based compounds contained in the ceramic material.

[0064] In the embodiments of the present invention, Cu 2-xTo prevent the formation of sulfur impurities, copper and phosphorus are used directly instead of using Cu3P as raw materials. That is, Cu is used as the primary raw material for copper and P is used as the primary raw material for phosphorus. CuSO4 may also be added as the primary raw material for copper. Furthermore, to reduce the formation of PbS impurities, PbO and PbSO4 are used as the primary raw materials for Pb instead of lanakite.

[0065] By using Cu or CuSO4 instead of elements with high copper content, such as Cu3P, as the main raw material for copper, the amount of residual Cu after the reaction can be significantly reduced, and accordingly, Cu 2-x It can prevent the formation of S impurities.

[0066] The reaction scheme of an apatite-based compound according to the embodiments of the present invention can be roughly expressed as the following reaction scheme 1.

[0067] (Scheme 1) (4-x)PbO + (6-v)PbSO4+ xCu + vCuSO4+ (6-y)P

[0068] → Pb 10-x-v Cu (x+v) (PO4) 6-y (SO4) y O z-w S w + αSO2+ βS8.

[0069] Here, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z 이다.

[0070] According to Reaction Equation 1 above, when the raw materials are mixed, vacuum-sealed, and subjected to a solid-state reaction in a temperature range of 500°C to 1000°C, apatite-based compounds are formed, leaving behind SO2 and S. By using the above raw materials, the amount of residual copper or lead other than the apatite-based compounds is reduced, so Cu 2-x Impurities such as copper sulfides like S or lead sulfides like PbS are reduced.

[0071] In Reaction Equation 1 above, the molar ratio of the raw materials is (PbO: PbSO4: Cu: CuSO4: P) = ((4-x): (6-v): x: v: (6-y)), where x, v, and y are 0 <x<4, 0≤v≤6, 및 0<y<3일 수 있다. 이 범위 내에서 구리황화물이나 PbS 등의 불순물을 감소시키고 아파타이트계 화합물의 순도를 높일 수 있다. 나아가, 구리의 원료로서 CuSO4도 제외될 수도 있으며, 이에 따라, 결정성이 양호한 아파타이트계 화합물을 얻을 수 있다.

[0072] FIG. 4 is a schematic cross-sectional view illustrating a vacuum tube (20) used to manufacture a conductive ceramic material according to one embodiment of the present invention, and FIG. 5 is a schematic cross-sectional view illustrating a degassing device (30) used to manufacture a conductive ceramic material according to one embodiment of the present invention.

[0073] First, referring to FIG. 4, the reaction raw materials described above are quantified and mixed, placed into a vacuum tube (20), and sealed. The vacuum tube (20) may be formed of, for example, quartz. The pressure inside the vacuum tube (20) is, for example, 10 -2 It can be lower than mTorr. For example, the pressure inside the vacuum tube (20) is about 10 -3 It could be mTorr.

[0074] A vacuum tube (20) is heated in a high-temperature furnace to synthesize an apatite-based compound by carrying out a solid-state reaction for 10 to 30 hours at a temperature range of, for example, 500°C to 1000°C. Subsequently, a product containing the synthesized apatite-based compound is separated from the vacuum tube (20). The vacuum tube (20) can be broken to separate the product. At this time, SO2, etc. are released in a gaseous state, and S8 is coated on the inner wall of the vacuum tube (20).

[0075] The product separated from the vacuum tube (20) can be crushed, placed in a crucible (41), and placed in a degassing device (30) as shown in FIG. 5. The degassing device (30) may include a pipe furnace (33) capable of vacuum pumping an outlet (37) and a heating wire (31) for heating the pipe furnace (33). Both ends of the pipe furnace (33) may be sealed with a sealing plug (35), and an outlet (37) may be provided at one end. A crucible (41) containing the product is placed inside the pipe furnace (33), and sealing plugs (35) are placed at both ends. By setting the vacuum level of the pipe furnace (33), the gas generated inside the pipe furnace (33) is discharged by a vacuum pump. The furnace (33) can be heated to a temperature of 300°C to 1000°C and maintained for 3 to 24 hours, and accordingly, sulfur can be vaporized and degassed from the product placed in the crucible (41).

[0076] Accordingly, a conductive ceramic material containing an apatite-based compound is manufactured. The apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and contains copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure.

[0077] Apatite-based compounds according to embodiments of the present invention can be represented, for example, by the following chemical formula 1.

[0078] (Chemical Formula 1)

[0079] Pb 10-x-v Cu (x+v) (PO4) 6-y (SO4) y O z-w S w (However, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z).

[0080] In one embodiment, v may be 0, and x may be less than 3.

[0081] (XRD Analysis)

[0082] Figure 6 is an XRD graph of the conductive ceramic material of Comparative Example 1 containing an apatite-based compound prepared according to the prior art. The conductive ceramic material of Comparative Example 1 was prepared by mixing lanakite and Cu3P in a 1:1 molar ratio according to the prior art.

[0083] Referring to Fig. 6, in addition to the peak of the apatite-based compound, Cu 2-x A peak of S is observed. Cu 2-x The peak of S appears in the range of 30 to 40 degrees.

[0084] Figure 7 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention. To prepare the conductive ceramic material of Example 1, PbO, PbSO4, Cu, and P were used as raw materials, and the molar ratio of the raw materials PbO:PbSO4:Cu:P was set to 3:6:1:6. That is, in the left-hand side of Reaction Scheme 1 above, v and y are 0, x is 1 (i.e., 1 mole of Cu), and the molar ratio of P to sulfur in the reaction raw materials is 1.

[0085] The raw materials were mixed and placed in a vacuum tube, and the vacuum tube was heated to synthesize an apatite-based compound at a temperature of about 700°C. The resulting product was then separated from the vacuum tube, and gases such as sulfur were vaporized and discharged from the resulting product using a degassing device to obtain a conductive ceramic material.

[0086] Referring to Fig. 7, compared with the XRD graph of Fig. 6, Cu 2-x No S peak is observed, and the peak of the apatite-based compound is clearly observed. That is, it can be seen that the conductive ceramic material prepared according to Example 1 contains a high-purity apatite-based compound.

[0087] FIG. 8 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 2 of the present invention. Example 2 is a conductive ceramic material containing an apatite-based compound prepared under all conditions identical to Example 1, except that x is set to 2 (i.e., 2 moles of Cu).

[0088] Referring to Fig. 8, even when the amount of Cu is increased to 2 moles, the peak of the apatite-based compound is clear, and Cu 2-x No S peak is observed.

[0089] FIG. 9 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 3 of the present invention. Example 3 is a conductive ceramic material containing an apatite-based compound prepared under all conditions identical to Example 1, except that x is set to 3 (i.e., 3 moles of Cu).

[0090] Referring to Fig. 9, even when the amount of Cu is increased to 3 moles, the peak of the apatite-based compound is clear, and Cu 2-x No S peak is observed.

[0091] Figure 10 is an XRD graph of the ceramic material according to Comparative Example 2. The ceramic material of Comparative Example 2 was prepared under the same conditions as Example 1, except that y was set to 4.5 (molar ratio of P to S was 0.25).

[0092] Referring to Figure 10, no peaks of apatite compounds are observed, and many peaks are observed in the range of 30 to 40 degrees, indicating that a relatively large amount of impurities were generated.

[0093] Figure 11 is an XRD graph of the ceramic material according to Comparative Example 3. The ceramic material of Comparative Example 3 was prepared under all the same conditions as Example 1, except that y was set to 3 (molar ratio of P to S was 0.5).

[0094] Referring to Figure 11, although peaks of apatite compounds are observed, many peaks are observed in the range of 30 to 40 degrees, indicating that a relatively large amount of impurities were generated.

[0095] FIG. 12 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 4 of the present invention. The ceramic material of Example 4 was prepared under all the same conditions as Example 1, except that y was set to 1.5 (molar ratio of P to S was 0.75).

[0096] Referring to FIG. 12, the conductive ceramic material of Example 4 shows a peak of an apatite-based compound, and no peak of impurities is clearly observed in the range of 30 to 40 degrees.

[0097] Figure 13 is an XRD graph of a conductive ceramic material containing an apatite-based compound according to Example 5 of the present invention. The ceramic material of Example 5 was prepared under all the same conditions as Example 1, except that y was set to 0.6 (molar ratio of P to S was 0.9).

[0098] Referring to FIG. 13, the conductive ceramic material of Example 5 shows a sharper peak of an apatite-based compound compared to the conductive ceramic material of Example 4, and also, no peak of impurities is clearly observed in the range of 30 to 40 degrees.

[0099] Comparing FIGS. 10 to 13, when synthesizing an apatite-based compound, if the molar ratio of P to S in the raw material is 0.5 or less, the apatite-based compound is not synthesized well and many impurity crystals are formed. On the other hand, the purity of the apatite-based compound can be increased by making the molar ratio of P used as a raw material greater than 0.5 relative to S. In order to reduce impurities and increase the purity of the apatite-based compound, the molar ratio of P to S must be greater than 0.5.

[0100] (Elemental composition and crystal structure analysis)

[0101] FIG. 14 is an SEM image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention, and FIG. 15 is an SEM-EDS image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention.

[0102] As shown in Fig. 14, crystals exist in powder form within the manufactured conductive ceramic material. Fig. 15 is an SEM-EDS image of the first particle (G1) of Fig. 14 and its surroundings, confirming that the first particle (G1) is composed of elements such as Pb, Cu, P, S, and O. SEM-EDS analysis was also performed on the second particle (G2) and the third particle (G3), and the same elements were detected.

[0103] FIG. 16 is a scanning transmission electron microscopy (STEM) image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention, where (b) is an enlarged view of (a). FIG. 16 is a STEM image of the first particle (G1), showing a plane perpendicular to the

[0011] direction. The atomic arrangement of a copper-doped lead apatite compound by simulation is superimposed on the upper left part of FIG. 16(a).

[0104] Referring to Fig. 16, it can be seen that the atoms in the first particle (G1) are arranged in the same way as copper-doped lead apatite.

[0105] FIG. 17 is a selected area electron diffraction (SAED) image of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention, shown together with a SAED image obtained by simulation. The SAED image in FIG. 17 is also a image of the first particle (G1).

[0106] Referring to FIG. 17, it can be seen that the diffraction pattern of the apatite compound according to Example 1 matches the simulated diffraction pattern of the copper-doped apatite compound.

[0107] FIG. 18 shows the wide-scan XPS spectrum of a conductive ceramic material containing an apatite-based compound according to Example 1 of the present invention, and FIG. 19 to 23 show the narrow-scan XPS (x-ray photoelectron spectroscopy) spectrum of a conductive ceramic material containing an apatite-based compound according to Example 1. An x-TOOL from ULVAC-PHI was used as the XPS equipment, and Al Kα was used as the X-ray source. The X-ray beam size was set to 100 µm, and the vacuum level was 6.7 x 10⁻⁶ -7 It was made to be less than Pa. The maximum beam current of the Ar sputter gun was made to be 5.0 μA or more at 5 kV.

[0108] The bonding structure of the elements of the apatite compound can be confirmed through XPS analysis. The elements can be identified by measuring the spectra of all elements in the sample using a wide scan, and the content of each element can be calculated using a narrow scan. A narrow scan was performed three times for each element, and the first narrow scan images for each element are shown in Figures 19 to 23.

[0109] Referring to FIGS. 18 to 23, it can be seen that the apatite compound is composed of Pb, Cu, P, S, and O. Additionally, referring to FIG. 22, oxygen (O 1s In the case of ), the difference in binding energy between the tetrahedral oxygen surrounding phosphorus and sulfur and the channel oxygen is not large, making it difficult to separate the spectra. However, the number of moles of oxygen forming the tetrahedron is significantly higher than the amount of channel oxygen. Meanwhile, referring to Fig. 23, S 2pThe binding energy of shows two distinct peaks, indicating that S has two positions. Analyzing the binding energy of S reveals that S exists in the form of SO4 at the phosphorus position within the tetrahedron surrounded by oxygen, and also exists as channel sulfur by being positioned at the channel oxygen position.

[0110] Using the values ​​measured through three narrow scans, the atomic percentage of each element of the apatite compound was calculated and the average value was obtained. From the atomic percentage of each element, the molar ratio of metal elements (Pb and Cu), the molar ratio of P and S located within the oxygen tetrahedron, and the molar ratio of sulfur and total oxygen in the channel were calculated. From this, the number of moles in the apatite compound was calculated and summarized in Table 1 below.

[0111] Average Value (Atomic %) Moles in Compound Pb 4f 19.77 8.99Cu 2p 2.23 1.01P 2p(PO4) 9.89 3.95S 2p(SO4) 5.12 2.05S 2p(MS) 7.70 3.65O 1s 5 5.29 24.34

[0112] From Table 1 above, the apatite-based compound obtained by Example 1 is approximately Pb 8.99 Cu 1.01 (PO4) 3.95 (SO4) 2.05 O 0.34 S 3.65 It can be seen that it can be represented as such. XPS analysis was performed in the same way for the apatite compound according to Example 3, and the average atomic % of three narrow scans and the number of moles in the compound calculated therefrom are summarized in Table 2 below.

[0113] Average Value (Atomic %) Moles in Compound Pb 4f 16.70 6.73Cu 2p 8.12 3.27P 2p(PO4) 13.93 5.47S 2p(SO4) 1.33 0.53S 2p(MS) 2.16 0.90O 1s 5 7.76 24.10

[0114] From Table 2 above, the apatite-based compound obtained by Example 3 is approximately Pb 6.73 Cu 3.27 (PO4) 5.47 (SO4) 0.53 O 0.1 S 0.9 It can be seen that it can be represented as such. Although the above chemical formula may be somewhat inaccurate due to impurities, as will be explained in detail later, the ceramic materials prepared in Examples 1 and 3 contain apatite-based compounds in high purity and have a relatively very small content of impurities. Therefore, the compositional formula of the obtained apatite-based compound will not deviate significantly from the above chemical formula.

[0115] Furthermore, from the above results, it can be seen that even when sufficient amounts of P are used as raw material, the SO4 form remains, and a significant amount of S remains as channel sulfur. Overall, the number of moles of sulfur is smaller than the number of moles of phosphorus, and furthermore, it can be seen that the number of moles of channel sulfur is larger than the number of moles of sulfur surrounded by oxygen tetrahedra.

[0116] To compare the amount of impurity compounds in apatite-based compounds according to the amount of P in the reaction raw materials, XRF (x-ray fluorescence) component analysis and XRD (x-ray diffraction) Rietveld analysis were performed on the samples of Comparative Examples 2 and 3 and Examples 4 and 5, and this is described. The samples of Comparative Examples 2 and 3 and Examples 4 and 5 were prepared with phosphorus corresponding to 0.25 mol, 0.5 mol, 0.75 mol, and 0.9 mol per 1 mol of sulfur in the raw materials, respectively, while all other process conditions were kept the same.

[0117] (XRF Analysis)

[0118] XRF analyzes elemental composition by utilizing the fluorescence emitted when electrons from outer orbits fill inner orbits after being excited by X-ray irradiation. Through XRF analysis, Pb, Cu, P, and S were analyzed, excluding oxygen, and the analyzed weight percentages for these elements are summarized in Table 3 below. By dividing the weight percentage values ​​of each element below by their atomic weights, the number of moles of each element contained in 100g of the sample can be calculated.

[0119] Atomic Weight Comparison Example 2 Comparison Example 3 Example 4 Example 5 Pb 20 7.28 9.7 wt%89 wt%89.7 wt%89 wt%Cu 6 3.54 61.6 wt%1.55 wt%2.88 wt%3.46 wt%P 3 0.97 41.82 wt%3.56 wt%4.31 wt%5.59 wt%S 3 2.06 66.84 wt%5.9 wt%3.09 wt%1.94 wt%

[0120] Referring to Table 3, it can be seen that in Comparative Examples 2 and 3, the weight percentage of phosphorus is smaller than the weight percentage of sulfur, whereas in Examples 4 and 5, the weight percentage of phosphorus is larger than the weight percentage of sulfur. Since the atomic weight of P is slightly smaller than that of sulfur, the above trend remains the same even when converting weight percentages to moles. That is, in Comparative Examples 2 and 3, the number of moles of P is smaller than the number of moles of sulfur, but in Examples 4 and 5, the number of moles of phosphorus is larger than the number of moles of sulfur. (XRD Rietveld analysis)

[0121] The amount of crystalline compounds in the sample can be determined through Rietveld analysis. The crystalline compounds and weight percent identified through XRD Rietveld analysis are summarized in Table 4.

[0122] Comparative Example 2 Comparative Example 3 Example 4 Example 5 Anglesite(I):51.9wt%Lanarkite: 30.9wt%Pb(SO4): 3.2wt%Minium: 5.9wt%Anglesite(II):3.0wt%Copper sulfate: 1.4wt%Pb2(P2O7): 3.6wt%Eulytite: 15.9wt%Anglesite(I): 6.8wt%Anglesite(II): 27.3wt%Apatite: 44.4wt%Villamaninite: 3.8%Minium: 1.6%Apatite: 72.9wt%Galena: 3.17wt%Anglesite: 18.4wt%Pb3(PO4)2: 5.6wt%Apatite: 96.8%Galena(I): 2.0wt%Galena: 1.2wt%

[0123] Referring to Table 4, in the case of Comparative Example 2, in which 0.25 moles of P were mixed with 1 mole of sulfur in the raw material, no apatite-based compounds were detected, and in Comparative Examples 2 and 3, and Examples 4 and 5, Cu through Rietveld analysis 2-x No impurities of S were detected. Meanwhile, in Comparative Example 3, the apatite compound accounted for 44.4% of the total weight of the total crystalline compounds, which was less than 50%. In contrast, in Examples 4 and 5, the apatite compound accounted for 72.9% and 96.8% of the total weight of the total crystalline compounds, respectively. From these results, it can be seen that if P is mixed at a ratio of approximately 0.6 moles or more per 1 mole of sulfur, the manufactured ceramic material can contain 50 wt% or more of the apatite compound among the total crystalline compounds. Furthermore, if the amount of P in the raw material is increased to 0.9 moles or more, the amount of the apatite compound contained in the ceramic material can be increased to 95 wt% or more.

[0124] Meanwhile, the amounts of P and S contained in the impurities can be calculated from the amount of impurities detected through Rietveld analysis, and the ratio of P and S in the apatite-based compound can be roughly determined by subtracting these amounts from the amount of each element detected in XRF.

[0125] The weight percentages of P and S in the apatite-based compounds of Comparative Example 3, Example 4, and 5 calculated through this are summarized in Table 5.

[0126] Comparative Example 3 Example 4 Example 5 P wt%0.8264.0965.590S wt%3.1660.7201.511

[0127] Referring to Table 5, it can be seen that in Comparative Example 3, the amount of S is greater than the amount of P, whereas in Examples 4 and 5, the amount of P is greater than the amount of S. Furthermore, dividing these wt%s by their atomic weights allows us to determine the number of moles of P and S per 100g of the apatite-based compound, and these moles also follow the above trend. That is, in Comparative Example 3, the number of moles of S is greater than the number of moles of P, whereas in Examples 4 and 5, the number of moles of P is greater than the number of moles of S. For Example 1, calculations performed in the same manner resulted in a P wt% of 6.420 and an S wt% of 0.852. Therefore, it can be seen that as the number of moles of P in the raw materials increases, the number of moles of P within the apatite-based compound also increases. (Electrical Characteristics)

[0128] FIG. 24 is an IV graph to explain the electrical characteristics of a conductive ceramic material manufactured according to the present invention. A conductive ceramic material coating layer with a thickness of approximately 0.5 μm was formed on a copper wire with a diameter of approximately 200 μm by thermal evaporation at approximately 250°C under vacuum conditions using the conductive ceramic material powder prepared in Example 1, and IV graphs were obtained for each of the two copper wires, one without a coating layer and one with a coating layer.

[0129] Referring to FIG. 24, it can be seen that the resistance of the copper wire in the embodiment (53) with the conductive ceramic material coating layer applied is lower than that of the comparative example (51) without the conductive ceramic material coating layer applied. Furthermore, assuming that copper of the same thickness as the conductive ceramic material coating layer is deposited, the expected voltage under a current of 5A is approximately 3.13V. However, when the conductive ceramic material coating layer is applied as in the embodiment, the value is approximately 2.83V under the same current, which is a decrease of more than 10%, indicating that the resistivity of the conductive ceramic material coating layer is smaller than that of copper.

[0130] FIG. 25 is a current-temperature graph to explain the heating characteristics of a conductive ceramic material manufactured according to the present invention. The temperature change of a copper wire according to the current was measured for two comparative examples (51) without a coating layer and two examples (53) with a coating layer, respectively.

[0131] Referring to FIG. 25, the temperature change of the copper wire in Example (53) with respect to current was significantly smaller compared to Comparative Example (51). It can be seen that the amount of heat generated by the copper wire was greatly reduced by applying a coating layer with low resistivity.

[0132] Although various embodiments and features of the present invention have been described above, the present invention is not limited to the embodiments and features described above and can be modified in various ways within the scope of the spirit of the present invention.

Claims

1. A method for manufacturing a conductive ceramic material comprising an apatite-based compound, The raw materials are placed in a vacuum tube and sealed, Apatite-based compounds are synthesized from the above raw materials by heating the above vacuum tube, and Separating the resulting product containing the apatite-based compound synthesized from the above vacuum tube, and The above product is heated to degasify the residual sulfur, but includes: As the above raw materials, the main raw material for lead includes PbO and PbSO4, the main raw material for copper includes Cu, and the main raw material for phosphorus includes P. The above apatite-based compound is lead phosphate apatite (Pb 10 A method for manufacturing a conductive ceramic material having a (PO4)6O) crystal structure and comprising copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure.

2. In Claim 1, The molar ratio of the above raw materials is (PbO: PbSO4: Cu: CuSO4: P) = ((4-x): (6-v): x: v: (6-y)), where x, v and y are 0 <x<4, 0≤v≤6, 및 0<y<3인 전도성 세라믹 재료 제조 방법.

3. In Claim 1, A method for manufacturing a conductive ceramic material in which the conductive ceramic material contains 50 wt% or more of the apatite-based compound based on the total weight of the total crystal system compound including the apatite-based compound.

4. In Claim 1, Cu in the above conductive ceramic material 2-x A method for manufacturing a conductive ceramic material in which the S crystal system compound is less than 1 wt% of the total weight of the total crystal system compound.

5. In a conductive ceramic material comprising an apatite-based compound, Apatite-based compounds and crystalline compounds other than the apatite-based compounds, wherein The above apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and includes copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure, and A conductive ceramic material containing 50 wt% or more of the apatite-based compound based on the total weight of the total crystalline compound including the apatite-based compound.

6. In Claim 5, A conductive ceramic material containing 90 wt% or more of the apatite-based compound based on the total weight of the entire crystalline compound including the apatite-based compound.

7. In Claim 5, Powdered conductive ceramic material.

8. In Claim 5, A conductive ceramic material in which the total number of moles of phosphorus contained therein is greater than the total number of moles of sulfur.

9. In Claim 5, A conductive ceramic material in which the total number of moles of phosphorus in the above apatite-based compound is greater than the total number of moles of sulfur.

10. In Claim 5, The crystal structure of the above apatite-based compound has channels formed by the arrangement of metal elements in the c-axis direction, and The above apatite-based compound is a conductive ceramic material further comprising sulfur disposed within the channel.

11. In Claim 5, The above apatite-based compound is a conductive ceramic material represented by the following chemical formula 1: (Chemical Formula 1) Pb 10-x-v Cu (x+v) (PO4) 6-y (SO4) y O z-w S w (However, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z).

12. In Claim 5, A conductive ceramic material having a copper sulfide content of less than 1 wt% relative to the total weight of the entire crystalline compound including the above apatite-based compound.

13. In Claim 5, A conductive ceramic material having a lead sulfide content of less than 4 wt% relative to the total weight of the entire crystalline compound including the above apatite-based compound.

14. In Claim 5, Cu relative to the total weight of the entire crystalline compound containing the above apatite-based compound 2-x Conductive ceramic material having a content of S crystal system compounds of less than 1 wt%.

15. In a conductive ceramic material comprising an apatite-based compound, Apatite-based compounds and crystalline compounds other than the apatite-based compounds, wherein The above apatite-based compound is lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and includes copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure, and The total moles of phosphorus contained are greater than the total moles of sulfur, and Cu relative to the total weight of the entire crystalline compound containing the above apatite-based compound 2-x A conductive ceramic material having a content of S crystal system compounds of less than 1 wt%.

16. In Claim 15, A conductive ceramic material in which the total number of moles of phosphorus in the above apatite-based compound is greater than the total number of moles of sulfur.

17. In Claim 15, The crystal structure of the above apatite-based compound has channels formed by the arrangement of metal elements in the c-axis direction, and The above apatite-based compound is a conductive ceramic material further comprising sulfur disposed within the channel.

18. In apatite-based compounds, Lead phosphate apatite (Pb 10 It has a (PO4)6O) crystal structure and includes copper and sulfur that partially substitute lead and phosphorus, respectively, within the crystal structure, and Apatite compounds in which the total moles of phosphorus contained in the compound are greater than the total moles of sulfur.

19. In Claim 18, It has a crystal structure in which channels are formed by the arrangement of metal elements along the c-axis direction, and Apatite-based compound further containing sulfur disposed within the above channel.

20. In Claim 18, Apatite compounds represented by the following chemical formula 1: (Chemical Formula 1) Pb 10-x-v Cu (x+v) (PO4) 6-y (SO4) y O z-w S w (However, 0 <x<4, 0≤v≤6, 0.9≤x+v≤9.9, 0<y<3, 0<z≤4, 및 0<w≤z).

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