KR0149421B1 - Superconductive materials synthesized by using sol-gel process - Google Patents
Superconductive materials synthesized by using sol-gel process Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 31
- 238000003980 solgel method Methods 0.000 title 1
- 239000002243 precursor Substances 0.000 claims abstract description 44
- 238000000034 method Methods 0.000 claims abstract description 43
- 239000000843 powder Substances 0.000 claims abstract description 35
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 30
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 30
- 230000008569 process Effects 0.000 claims abstract description 29
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 28
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 28
- 239000007864 aqueous solution Substances 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 12
- 238000005245 sintering Methods 0.000 claims abstract description 12
- 239000011259 mixed solution Substances 0.000 claims abstract description 11
- 229910052802 copper Inorganic materials 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims description 9
- 229910001960 metal nitrate Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 150000002823 nitrates Chemical class 0.000 claims description 2
- 230000002194 synthesizing effect Effects 0.000 claims 1
- 239000013078 crystal Substances 0.000 abstract description 11
- 239000000919 ceramic Substances 0.000 abstract description 7
- 229910002651 NO3 Inorganic materials 0.000 abstract description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 abstract description 5
- 239000000835 fiber Substances 0.000 abstract description 4
- 239000012452 mother liquor Substances 0.000 abstract description 4
- 239000010409 thin film Substances 0.000 abstract description 4
- 239000010419 fine particle Substances 0.000 abstract description 3
- 229940068984 polyvinyl alcohol Drugs 0.000 description 24
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 24
- 239000002245 particle Substances 0.000 description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 9
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 238000004455 differential thermal analysis Methods 0.000 description 6
- 238000003746 solid phase reaction Methods 0.000 description 5
- 230000004580 weight loss Effects 0.000 description 5
- 238000000498 ball milling Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000002411 thermogravimetry Methods 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 238000010671 solid-state reaction Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910001422 barium ion Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000002887 superconductor Substances 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/624—Sol-gel processing
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/62605—Treating the starting powders individually or as mixtures
- C04B35/62645—Thermal treatment of powders or mixtures thereof other than sintering
- C04B35/62675—Thermal treatment of powders or mixtures thereof other than sintering characterised by the treatment temperature
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
- C04B35/632—Organic additives
- C04B35/634—Polymers
- C04B35/63404—Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B35/63416—Polyvinylalcohols [PVA]; Polyvinylacetates
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
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- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/80—Constructional details
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- H10N60/855—Ceramic superconductors
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Abstract
본 발명은 Y, Ba, Cu의 질산염 수용액과 PVA(Poly Vinyl Alcohol)수용액을 혼합하는 제1단계 ; 상기 혼합용액을 건조하여 얻은 암청색의 투명한 졸을 얻는 제2단계 ; 상기 제2단계에서 얻어진 졸을 건조하여 겔 전구체를 얻는 제3단계 ; 상기 제3단계에서 얻은 겔 전구체를 500℃에서 전처리하여 전구체 분말을 얻는 제4단계 ; 상기 제4단계에서 얻어진 전구체 분말을 800~920℃에서 소결하여 YBa2Cu3O7-X의 결정 분말을 얻는 제5단계의 공정을 포함하는 것을 특징으로 하는 YBa2Cu3O7-X초전도물질 합성공정으로서, 본 발명에 의한 YBa2Cu3O7-X초전도물질은 분말의 입자가 균일하고 미세하여 세라믹형의 취성을 극복하였고, 본 발명의 공정중에 얻어지는 졸과 겔은 제품의 특성이 우수한 박막 및 섬유를 제조하는 모액으로서 사용될 수도 있다.The present invention is a first step of mixing a nitrate aqueous solution of Y, Ba, Cu and a polyvinyl alcohol (PVA) solution; A second step of obtaining a dark blue transparent sol obtained by drying the mixed solution; A third step of obtaining a gel precursor by drying the sol obtained in the second step; A fourth step of pretreating the gel precursor obtained in the third step at 500 ° C. to obtain precursor powder; YBa 2 Cu 3 O 7-X superconducting comprising the step of obtaining a crystal powder of YBa 2 Cu 3 O 7-X by sintering the precursor powder obtained in the fourth step at 800 ~ 920 ℃ As a material synthesis process, the YBa 2 Cu 3 O 7-X superconducting material according to the present invention overcomes ceramic brittleness due to uniform and fine particles of powder, and the sol and gel obtained during the process of the present invention have characteristics of the product. It can also be used as a mother liquor to produce excellent thin films and fibers.
Description
제1도는 종래기술인 고상반응법에 의한 YBa2Cu3O7-X합성공정의 블록도.1 is a block diagram of a YBa 2 Cu 3 O 7-X synthesis process by the solid state reaction method of the prior art.
제2도는 본 발명인 졸-겔을 이용한 YBa2Cu3O7-X합성공정의 블록도.2 is a block diagram of a YBa 2 Cu 3 O 7-X synthesis process using a sol-gel of the present invention.
제3도는 본 발명에 의한 합성공정에 의하여 합성된 YBa2Cu3O7-X의 초전도성을 보여주는 그래프.3 is a graph showing the superconductivity of YBa 2 Cu 3 O 7-X synthesized by the synthesis process according to the present invention.
제4도는 본 발명에 의한 합성공정에 의하여 합성된 YBa2Cu3O7-X의 입자의 크기를 보여주는 SEM사진.Figure 4 is a SEM photograph showing the size of the particles of YBa 2 Cu 3 O 7-X synthesized by the synthesis process according to the present invention.
제5도는 PVA와 본 발명에 의한 합성공정의 겔 전구체의 열중량분석그래프.5 is a thermogravimetric analysis graph of PVA and gel precursor of the synthesis process according to the present invention.
제6도는 PVA와 본 발명에 의한 합성공정의 겔 전구체의 시차열분석그래프.6 is a differential thermal analysis graph of PVA and the gel precursor of the synthesis process according to the present invention.
제7도는 겔 전구체와 각기 다른 온도에서 소결처리된 겔 전구체들의 X선 회절 패턴.7 is an X-ray diffraction pattern of gel precursors and gel precursors sintered at different temperatures.
제8도는 YBa2Cu3O7-X의 결정화 온도를 결정하기 위한 시차열분석 그래프이다.8 is a differential thermal analysis graph for determining the crystallization temperature of YBa 2 Cu 3 O 7-X .
본 발명은 초전도물질인 YBa2Cu3O7-X의 합성공정에 관한 것으로서, 특히 합성공정 도중에 졸-겔 상태를 포함하는 YBa2Cu3O7-X의 합성공정에 관한 것이다.The present invention relates to the synthesis of the superconducting material YBa 2 Cu 3 O 7-X , and more particularly to the synthesis of YBa 2 Cu 3 O 7-X including a sol-gel state during the synthesis process.
YBa2Cu3O7-X은 특정 온도영역에서 전기적 저항이 없어지는 초전도물질로서 특히 세라믹형 초전도물질이다.YBa 2 Cu 3 O 7-X is a superconducting material that loses electrical resistance in a certain temperature range, especially ceramic type superconducting material.
종래의 기술에 의하여 YBa2Cu3O7-X과 같은 산화물 초전도체를 얻는 일반적인 방법은 각 구성성분의 산화물 또는 탄상염을 몰비로 혼합하여 하소 및 소결 반응을 거치는 고상반응법이 있다.The conventional method for obtaining an oxide superconductor such as YBa 2 Cu 3 O 7 -X by the conventional technique is a solid phase reaction method in which oxidization or carbonation salt of each component is mixed in a molar ratio to undergo calcination and sintering reactions.
제1도는 종래기술인 고상반응법에 의한 YBa2Cu3O7-X합성공정의 블록도이다.Figure 1 is a block diagram of a YBa 2 Cu 3 O 7-X synthesis process by the solid state reaction method of the prior art.
YBa2Cu3O7-X를 구성하는 성분에 대한 반응물로서 Y2O3, BaCO2, CuO분말을 분쇄하고 고르게 혼합하는 과정인 볼밀링단계를 거친다.As a reactant for the components constituting YBa 2 Cu 3 O 7-X , a ball milling step of grinding and evenly mixing Y 2 O 3 , BaCO 2 and CuO powders is performed.
그런 다음 약 950℃에서 20~50시간정도 소성하는 단계를 거친다.Then, the step is fired at about 950 ° C. for 20 to 50 hours.
가열된 분말혼합물을 냉각시킨다.The heated powder mixture is cooled.
상기와 같은 볼밀링, 소성, 냉각의 과정을 3~4회 반복하여 YBa2Cu3O7-X분말을 얻는다.YBa 2 Cu 3 O 7-X powder is obtained by repeating the above-described processes of ball milling, firing, and cooling 3 to 4 times.
그러나 상기와 같은 고상반응법에 의한 YBa2Cu3O7-X합성공정은 첫째, 볼밀링단계에서 불순물이 유입될 가능성이 많고, 둘째, 볼밀링에 의하여는 입도분포가 균일하고 미세한 입자를 얻는데 한계가 있고, 셋째, 소성단계에서 높은 온도에서 장시간 가열하여야 하는 단점이 있다.However, YBa 2 Cu 3 O 7-X synthesis process by the solid-phase reaction method as described above, firstly, impurities are likely to be introduced in the ball milling step, and second, ball milling has a uniform particle size distribution to obtain fine particles. There is a limit, and thirdly, there is a disadvantage in that the heating step for a long time at high temperature.
고상반응법에 의하여 얻어진 YBa2Cu3O7-X분말은 입자의 크기가 매우 크고, 입도가 균일하지 않으며 성형체의 경우 높은 기공도를 갖는 경우가 많아 이를 개선한 것으로 습식법에 의한 초전도체 분말 합성공정이 있는데, 대표적인 습식법으로는 구연산법이 있다.The YBa 2 Cu 3 O 7-X powder obtained by the solid-phase reaction method has a very large particle size, a uniform particle size and a high porosity in the case of a molded product. There is a typical wet method is citric acid method.
YBa2Cu3O7-X와 같은 세라믹형 초전도물질은 불말의 입자가 균일하고 미세할수록 취성에 유리하다.Ceramic type superconducting materials such as YBa 2 Cu 3 O 7-X are more brittle as the particles are uniform and fine.
그러나, 구연산법을 사용하여 얻어지는 YBa2Cu3O7-X분말의 입자 크기가 1~2㎛에 이르고 있는 실정으로 세라믹형 초전도물질의 취성이 불리하게 된다.However, in the fact that the particle size of the YBa 2 Cu 3 O 7-X powder obtained using the citric acid method reaches 1 to 2 µm, brittleness of the ceramic superconducting material becomes disadvantageous.
본 발명의 목적은 균일하고도 미세한 YBa2Cu3O7-X분말을 얻는 합성물질을 제공하는 것이다.It is an object of the present invention to provide a synthetic material which obtains a uniform and fine YBa 2 Cu 3 O 7 -X powder.
본 발명의 목적을 달성하기 위하여, 본 발명은 종래의 YBa2Cu3O7-X합성공정을 획기적으로 개선한 것으로서, Y, Ba, Cu의 질산염 수용액과 PVA(Poly Vinyl Alcohol)수용액을 혼합하는 제1단계 ; 상기 혼합용액을 건조하여 얻은 암청색의 투명한 졸을 얻는 제2단계 ; 상기 제2단계에서 얻어진 졸을 건조하여 겔 전구체를 얻는 제3단계 ; 상기 제3단계에서 얻은 겔전구체를 500℃에서 전처리하여 전구체 분말을 얻는 제4단계 ; 상기 제4단계에서 얻어진 전구체 분말을 800~920℃에서 소결하여 YBa2Cu3O7-X의 결정 분말을 얻는 제5단계의 공정을 포함한다.In order to achieve the object of the present invention, the present invention is a significant improvement of the conventional YBa 2 Cu 3 O 7-X synthesis process, by mixing the nitrate aqueous solution of Y, Ba, Cu and polyvinyl alcohol (PVA) aqueous solution First step; A second step of obtaining a dark blue transparent sol obtained by drying the mixed solution; A third step of obtaining a gel precursor by drying the sol obtained in the second step; A fourth step of pretreating the gel precursor obtained in the third step at 500 ° C. to obtain precursor powder; And a fifth step of obtaining the crystal powder of YBa 2 Cu 3 O 7 -X by sintering the precursor powder obtained in the fourth step at 800 to 920 ° C.
이하에서 도면을 참조하면서 본 발명에 의한 YBa2Cu3O7-X합성공정을 상세하게 설명한다.Hereinafter, with reference to the drawings will be described in detail the YBa 2 Cu 3 O 7-X synthesis process according to the present invention.
제2도는 본 발명인 졸-겔을 이용한 YBa2Cu3O7-X합성공정의 블록도이다.Figure 2 is a block diagram of the YBa 2 Cu 3 O 7-X synthesis process using the sol-gel of the present invention.
제1단계 : Y, Ba, Cu의 질산염 수용액과 PVA 수용액을 혼합하는 단계First step: mixing the nitrate aqueous solution of Y, Ba, Cu and PVA aqueous solution
YBa2Cu3O7-X을 구성하는 Y, Ba, Cu를 제공하는 반응물로는 Y, Ba, Cu의 질산염인 Y(NO3)3·6H2O, Ba(NO3)2, Cu(NO3)3·3H2O을 각각 사용한다.The reactants for providing Y, Ba and Cu constituting YBa 2 Cu 3 O 7-X include Y (NO 3 ) 3 .6H 2 O, Ba (NO 3 ) 2 , Cu ( NO 3 ) 3 · 3H 2 O is used respectively.
YBa2Cu3O7-X을 구성하는 Y, Ba, Cu의 몰비가 1 : 2 : 3이므로, 각 금속의 질산염인 Y(NO3)3·6H2O, Ba(NO3)2, Cu(NO3)3·3H2O을 1 : 2 : 3의 몰비로 혼합하고, 상기 혼합물을 물에 용해시켜서 금속질산염혼합물의 수용액을 만든다.Since the molar ratio of Y, Ba and Cu constituting YBa 2 Cu 3 O 7-X is 1: 2: 3, Y (NO 3 ) 3 · 6H 2 O, Ba (NO 3 ) 2 , Cu, which is a nitrate of each metal (NO 3 ) 3 .3H 2 O is mixed in a molar ratio of 1: 2: 3, and the mixture is dissolved in water to form an aqueous solution of the metal nitrate mixture.
상기 금속질산염혼합물의 수용액과 PVA 수용액을 혼합한다.The aqueous solution of the metal nitrate mixture and the aqueous solution of PVA are mixed.
이때, 금속질산염혼합물의 수용액과 PVA 수용액의 혼합용액에서 PVA/총금속의 몰비는 10이상 25이하이어야 한다. PVA/총금속의 몰비는 10이하인 경우에는 반응물중에서 Ba(NO3)2가 남아서 백색의 침전이 형성된다. 그 이유는 Ba(NO3)2가 산성조건하에서는 PVA와의 상호작용이 약해서 Ba(NO3)2침전이 되고, PVA의 양이 증가할수록 pH가 중성이 되어서 Ba이온과 PVA와의 상호작용이 강해지기 때문이다.At this time, the molar ratio of PVA / total metal in the mixed solution of the metal nitrate mixture and the PVA solution should be 10 or more and 25 or less. If the molar ratio of PVA / total metal is 10 or less, Ba (NO 3 ) 2 remains in the reaction, forming a white precipitate. The reason is that Ba (NO 3 ) 2 is weakly interacted with PVA under acidic conditions, resulting in precipitation of Ba (NO 3 ) 2 , and as the amount of PVA increases, the pH becomes neutral and the interaction between Ba ions and PVA becomes stronger. Because.
표 1은 PVA/총금속의 여러 가지 다른 몰비에 따른 금속질산염혼합물의 수용액과 PVA수용액의 혼합용액이 형성하는 졸에서의 Ba(NO3)2침전량을 측정한 자료이다.Table 1 shows the measurement of Ba (NO 3 ) 2 precipitation in the sol formed by the mixed solution of the metal nitrate mixture and the PVA aqueous solution according to the different molar ratios of PVA / total metal.
표 1에서 보이는 바와 같이, PVA/총금속의 몰비가 10이상인 경우에만 이 금속질산염혼합물이 수용액과 PVA수용액의 혼합용액이 투명한 졸을 형성할 수 있다.As shown in Table 1, only when the molar ratio of PVA / total metal is 10 or more, the metal nitrate mixture may form a sol in which the mixed solution of the aqueous solution and the PVA solution is transparent.
제2단계 : 금속질산염혼합물의 수용액과 PVA 수용액의 혼합용액을 건조하여 얻은 암청색의 투명한 졸을 얻는 단계Step 2: obtaining a dark blue transparent sol obtained by drying the mixed solution of the metal nitrate mixture and the PVA aqueous solution
제1단계에서 얻어진 혼합용액을 70~80℃로 유지된 자석교반기에서 건조시켜서 투명한 암청색의 졸을 얻는다.The mixed solution obtained in the first step is dried in a magnetic stirrer maintained at 70 to 80 ° C. to obtain a clear dark blue sol.
제3단계 : 졸을 건조하여 겔 전구체를 형성하는 단계Step 3: drying the sol to form a gel precursor
제2단계에서 얻어진 투명한 암청색의 졸을 70~80℃로 유지된 자석교반기에서 건조시켜서 겔을 얻는다. 이 상태의 겔을 겔 전구체라고 하기로 한다.The clear dark blue sol obtained in the second step is dried in a magnetic stirrer maintained at 70 to 80 ° C. to obtain a gel. The gel in this state will be referred to as a gel precursor.
상기 제2단계에서 얻어진 졸과 상기 제3단계에서 얻어진 겔 전구체들은 회전피복법(Spining Coating) 및 열분해법(Dipping Pyrolysis)을 이용한 박막, 섬유, 전선 등의 선재가공시 모액으로서 제공될 수 있다.The sol obtained in the second step and the gel precursors obtained in the third step may be provided as a mother liquor during wire processing of thin films, fibers, wires, etc. using Spinning Coating and Dipping Pyrolysis.
제4단계 : 겔 전구체를 500℃에서 전처리하여 전구체 분말을 얻는 단계Step 4: pretreatment of the gel precursor at 500 ℃ to obtain a precursor powder
제3단계에서 얻어진 겔 전구체를 500℃에서 2시간동안 가열하면, 겔상태에서 분말의 형태를 얻을 수 있는데, 이러한 분말은 최종 생성물인 YBaCuO결정 분말의 전구체 분말이라고 하기로 한다.When the gel precursor obtained in the third step is heated at 500 ° C. for 2 hours, a powder can be obtained in a gel state. This powder is referred to as a precursor powder of YBaCuO crystal powder, which is a final product.
이러한 전구체 분말을 시차열분석하면 YBaCuO초전도물질의 결정온도를 측정할 수 있다.Differential thermal analysis of such precursor powder can determine the crystal temperature of the YBaCuO superconducting material.
본 발명에 의한 합성공정에서 얻어진 전구체 분말을 시차열분석한 결과, YBaCuO초전도물질의 결정온도는 약 800℃로 측정되었다.As a result of differential thermal analysis of the precursor powder obtained in the synthesis process according to the present invention, the crystal temperature of the YBaCuO superconducting material was measured to be about 800 ° C.
따라서, YBaCuO초전도물질의 결정분말을 얻는 다음의 단계에서는 소결온도가 800℃이상이 되어야 함을 알 수 있다.Therefore, it can be seen that the sintering temperature should be 800 ° C. or higher in the next step of obtaining the crystal powder of the YBaCuO superconducting material.
제5단계 : 전구체 분말을 소결하여 YBaCuO의 결정 분말을 얻는 단계Step 5: sintering the precursor powder to obtain crystal powder of YBaCuO
제4단계에서 얻어진 전구체 분말을 800~900℃에서 소결하여 YBaCuO초전도물질의 결정분말을 얻는다.Precursor powder obtained in the fourth step is sintered at 800 ~ 900 ℃ to obtain a crystal powder of the YBaCuO superconducting material.
본 발명에 의한 합성공정에 의하여 얻어진 YBaCuO초전도물질의 결정분말은 용융탄상염연료전지(MCFC)의 대체 캐소드(cathode)로 사용될 수 있다.The crystal powder of the YBaCuO superconducting material obtained by the synthesis process according to the present invention can be used as an alternative cathode of a molten carbon salt fuel cell (MCFC).
제3도 및 제4도는 본 발명에 의하여 합성된 YBaCuO초전도물질의 특성을 보여주는 도면으로서, 합성된 YBaCuO의 초전도성을 보여주는 그래프이고, 제4도는 YBaCuO의 입자가 크기를 보여주는 SEM 사진이다.3 and 4 are graphs showing the properties of the YBaCuO superconducting material synthesized by the present invention, a graph showing the superconductivity of the synthesized YBaCuO, Figure 4 is a SEM photograph showing the size of the particles of YBaCuO.
제3도는 그래프에서 가로축은 절대온도를 나타내고, 세로축은 온도에 따른 전기저항(R)을 상온(298K)에서의 전기저항(R)에 대한 비율로 표시한 것이다.3, the horizontal axis represents absolute temperature in the graph, and the vertical axis represents the electrical resistance R according to the temperature as a ratio of the electrical resistance R at room temperature (298K).
제3도에서 보이는 바와 같이, 상온(298K)에서부터 온도가 감소함에 따라 전기저항이 감소하다가 97~94K부근에서 저항이 0이 되는 초전도성이 관찰된다.As shown in FIG. 3, the electrical resistance decreases as the temperature decreases from room temperature (298K), and superconductivity is observed in which resistance becomes zero near 97-94K.
세라믹형 초전도물질의 특성에 따라서 천이온도를 가지는데, 천이시작온도는 97.3K이고, 천이종료온도는 94K로 측정되어 천이온도영역(ΔT)은 3.3K였다.According to the characteristics of the ceramic superconducting material, it has a transition temperature. The transition start temperature is 97.3K and the transition end temperature is 94K, and the transition temperature range ΔT is 3.3K.
제4도는 본 발명의 제5단계에서 920℃에서 소결하여 얻은 YBaCuO초전도물질의 시편이 주사전자현미경(SEM) 사진으로서 평균입자의 지름이 25㎚로 측정되었다.4 is a scanning electron microscope (SEM) photograph of the YBaCuO superconducting material obtained by sintering at 920 ° C. in the fifth step of the present invention, and the average particle diameter was measured at 25 nm.
이러한 결과는 종래의 구연산법에 의하여 얻은 1~2㎛에 비하여 훨씬 미세한 것으로서, 본 발명에 의하여 합성된 YBaCuO분발은 입자가 미세하기 때문에 소결성이 우수하여 한계전류밀도가 높을 것으로 예상되며, 미세한 입자로 인하여 세라믹형 초전도물질이 가지는 취성을 극복하여 전선등의 선재 가공에 용이하게 사용될 수 있는 장점이 있다.These results are much finer than 1 ~ 2㎛ obtained by the conventional citric acid method, the YBaCuO powder synthesized by the present invention is expected to have a high limiting current density due to the fine sintering properties because the particles are fine, fine particles Due to the brittleness of the ceramic superconducting material has an advantage that can be easily used in wire processing such as wire.
또한, 본 발명에 의한 합성공정의 제2단계에서 얻어지는 졸과 제3단계에서 얻어지는 겔은 제품의 특성이 우수한 박막 및 섬유를 제조하는 모액으로서 사용될 수도 있다.In addition, the sol obtained in the second step of the synthesis process according to the present invention and the gel obtained in the third step may be used as a mother liquor for producing thin films and fibers having excellent product properties.
이하에서는 본 발명에 의한 합성공정의 단계에서 측정된 여러 가지 분석결과를 설명한다.Hereinafter, various analysis results measured at the stage of the synthesis process according to the present invention will be described.
제5도는 PVA와 본 발명에 의한 합성공정의 겔 전구체의 열중량분석 그래프이고, 제6도는 PVA와 본 발명에 의하 합성공정의 겔 전구체의 시차열분석(Differential Thermal Analysis)그래프이다.5 is a thermogravimetric analysis graph of PVA and a gel precursor of the synthesis process according to the present invention, and FIG. 6 is a differential thermal analysis graph of PVA and a gel precursor of the synthesis process according to the present invention.
제5도와 제6도에서 (a)는 PVA이고, (b)는 겔 전구체이다.In Figures 5 and 6, (a) is PVA and (b) is a gel precursor.
제5도의 열중량분석은 400㏄/min의 공기유속과 5℃/min의 가열속도로 수행된 것이다.The thermogravimetric analysis of FIG. 5 was performed at an air flow rate of 400 kPa / min and a heating rate of 5 ° C / min.
제5도에서 보이는 열중량분석에 의하면, 겔 전구체의 무게감소는 440℃에서 끝났으나, PVA의 경우는 600℃까지 계속되었다.Thermogravimetric analysis shown in FIG. 5 showed that the weight loss of the gel precursor ended at 440 ° C., but continued to 600 ° C. for PVA.
겔 전구체의 무게감소는 40~140℃, 140~360℃, 360~440℃의 세구간에서 일어났다. 40~140℃의 무게감소는 물의 증발에 기인한 것으로 제6에서의 85℃ 흡열피크의 결과와 일치하는 것이다. 140~360℃의 무게감소는 질산염의 분해에 의한 것이고 제6도에서의 310℃발열피크와 일치하는 것이다. 360~440℃의 무게감소는 유기물질의 분해에 의한 것으로 겔 전구체와 각기 다른 온도에서 열처리된 겔 전구체들의 X선 회절 패턴을 보여주는 제7도에서 보이는 바와 같이, 유기물질의 분해는 3단계로 나누어진다. 이는 제7도에서 설명하기로 한다.The weight loss of the gel precursor occurred in three sections of 40-140 ° C, 140-360 ° C, and 360-440 ° C. The weight loss of 40-140 ° C is due to the evaporation of water and is consistent with the result of the 85 ° C endothermic peak in the sixth. The weight loss of 140-360 ° C is due to the decomposition of nitrates and is consistent with the 310 ° C exothermic peak in FIG. The weight loss of 360 ~ 440 ℃ is due to decomposition of organic materials, and as shown in FIG. Lose. This will be described in FIG.
제6도의 (b)에서 363℃, 392℃, 425℃에서 3개의 발열피크가 관찰되는데, 이는 겔 전구체 시편에 남아있는 PVA와 Ba, Cu, Y 이온이 BaCO, CuO와 YO를 생성하면서 생성되는 반응열로 추정된다.In (b) of FIG. 6, three exothermic peaks were observed at 363 ° C., 392 ° C. and 425 ° C., in which PVA, Ba, Cu, and Y ions remaining in the gel precursor specimen were produced while generating BaCO, CuO and YO. It is estimated by the heat of reaction.
제7도는 겔 전구체와 각기 다른 온도에서 소결처리된 겔 전구체들의 X선 회절 패턴을 보여주는 것이다.FIG. 7 shows the X-ray diffraction pattern of gel precursors and gel precursors sintered at different temperatures.
(a)는 겔 전구체의 X선 회절패턴이고, (b), (c), (d), (e)는 각각 500℃, 800℃, 900℃, 920℃로 2시간 소결처리된 겔 전구체들의 X선 회절패턴이다.(a) is the X-ray diffraction pattern of the gel precursor, and (b), (c), (d) and (e) are the gel precursors sintered at 500 ° C, 800 ° C, 900 ° C and 920 ° C for 2 hours, respectively. X-ray diffraction pattern.
제7도는 X선 회절패턴에서 B는 BaCO, C는 CuO, Y는 YO, O은 YCuO, ●은 YBaCuO를 각각 나타내는 것이다.7 shows B in the X-ray diffraction pattern, B represents BaCO, C represents CuO, Y represents YO, O represents YCuO, and ● represents YBaCuO.
겔전구체(a)의 경우는 무정형이고, 500℃, 2시간 시편(b)에서는 BaCO, CuO와 YO가 관찰되었을 뿐만 아니라, 소량의 YCuO피크가 나타났다.In the gel precursor (a), amorphous, BaCO, CuO and YO were observed in the specimen (b) at 500 ° C. for 2 hours, and a small amount of YCuO peak was observed.
800℃, 2시간 소결처리된 시편(c)의 경우는 소량의 BaCO와 YO가 관찰되었으나 대부분은 YBaCuO이었다.In case of specimen (c) sintered at 800 ° C. for 2 hours, small amounts of BaCO and YO were observed, but most of them were YBaCuO.
900℃, 2시간 소결처리한 시편(d)의 경우는 대부분의 중간 생성물이 사라지고 단일상의 YBaCuO초전도물질이 생성되었다.In the specimen (d) after sintering at 900 ° C. for 2 hours, most of the intermediate product disappeared and a single phase YBaCuO superconducting material was produced.
920℃, 2시간 소결처리한 시편(e)에서는 2θ=46.6℃의 피크와 2θ=58.1°의 피크가 분리되었으며 피크의 세기가 커졌다.In specimen (e) subjected to sintering at 920 ° C. for 2 hours, a peak at 2θ = 46.6 ° C. and a peak at 2θ = 58.1 ° were separated, and the intensity of the peak was increased.
위의 결과들을 종합하면, YBaCuO초전도물질은 YO, BaCO, CuO사이의 반응을 통하여 생성되는 것임을 알 수 있다.Summarizing the above results, it can be seen that YBaCuO superconducting material is generated through the reaction between YO, BaCO, CuO.
제8도는 YBaCuO의 결정화 온도를 결정하기 위한 시차열분석 그래프이다.8 is a differential thermal analysis graph for determining the crystallization temperature of YBaCuO.
YBaCuO초전도물질의 결정화온도를 측정하기 위하여, DTA 측정전 220℃에서 열분해시킨 분말 전구체를 DTA곡선을 얻었다.In order to measure the crystallization temperature of the YBaCuO superconducting material, a DTA curve was obtained for the powder precursor pyrolyzed at 220 ° C. before the DTA measurement.
제8도에서 보이는 바와 같이, YBaCuO초전도물질의 결정과 온도는 약 800℃인 것임을 알 수 있다. 이러한 결과는 제7도에서 800℃, 2시간 소결처리한 시편(c)의 X선 회절패턴 분석 결과 대부분이 YBaCuO인 결과와 일치 것이다.As shown in Figure 8, it can be seen that the crystal and the temperature of the YBaCuO superconducting material is about 800 ℃. This result is consistent with the result of X-ray diffraction pattern analysis of the specimen (c) sintered at 800 ° C. for 2 hours in FIG. 7.
제8도에서 관측된 결과에 의하여 YBaCuO초전도물질을 합성하려면 본 발명이 제5단계에서 최소한 800℃이상으로 소결철하여야하함을 알 수 있다.In order to synthesize the YBaCuO superconducting material according to the results observed in FIG. 8, it can be seen that the present invention should be sintered to at least 800 ° C. or more in the fifth step.
이상에서 설명한 바와 같이, 본 발명은 Y, Ba, Cu의 질산염 수용액과 PVA(Poly Vinyl Alcohol)수용액을 혼합하는 제1단계 ; 상기 혼합용액을 건조하여 얻은 암청색의 투명한 졸을 얻는 제2단계 ; 상기 제2단계에서 얻어진 졸을 건조하여 겔 전구체를 얻는 제3단계 ; 상기 제3단계에서 얻은 겔전구체를 500℃에서 전처리하여 전구체 분말을 얻는 제4단계 ; 상기 제4단계에서 얻어진 전구체 분말을 800~920℃에서 소결하여 YBaCuO의 결정 분말을 얻는 제5단계의 공정을 포함하는 것을 특징으로 하는 YBaCuO초전도물질 합성공정으로서, 본 발명에 의한 YBaCuO초전도물질은 분말의 입자가 균일하고 미세하여 세라믹형의 취성을 극복하였고, 본 발명의 공정중에 얻어지는 졸과 겔은 제품의 특성이 우수한 박막 및 섬유를 제조하는 모액으로서 사용될 수도 있다.As described above, the present invention is a first step of mixing a nitrate aqueous solution of Y, Ba, Cu and a poly vinyl alcohol (PVA) solution; A second step of obtaining a dark blue transparent sol obtained by drying the mixed solution; A third step of obtaining a gel precursor by drying the sol obtained in the second step; A fourth step of pretreating the gel precursor obtained in the third step at 500 ° C. to obtain precursor powder; YBaCuO superconducting material synthesis process comprising the step of obtaining a crystal powder of YBaCuO by sintering the precursor powder obtained in the fourth step at 800 ~ 920 ℃, YBaCuO superconducting material according to the present invention is a powder The particles of uniform and fine overcome the ceramic brittleness, and the sol and gel obtained in the process of the present invention may be used as a mother liquor for producing thin films and fibers having excellent product properties.
Claims (6)
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| KR970006233A KR970006233A (en) | 1997-02-19 |
| KR0149421B1 true KR0149421B1 (en) | 1998-10-15 |
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