WO1990005384A1 - Superconducting metal oxide compositions and processes for manufacture and use - Google Patents
Superconducting metal oxide compositions and processes for manufacture and use Download PDFInfo
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- WO1990005384A1 WO1990005384A1 PCT/US1989/004477 US8904477W WO9005384A1 WO 1990005384 A1 WO1990005384 A1 WO 1990005384A1 US 8904477 W US8904477 W US 8904477W WO 9005384 A1 WO9005384 A1 WO 9005384A1
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- temperature
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- 239000000203 mixture Substances 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 title abstract description 3
- 229910044991 metal oxide Inorganic materials 0.000 title description 4
- 150000004706 metal oxides Chemical class 0.000 title description 4
- 239000000463 material Substances 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 10
- 150000002978 peroxides Chemical class 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 3
- 230000000977 initiatory effect Effects 0.000 claims description 2
- 239000004020 conductor Substances 0.000 claims 4
- 239000010949 copper Substances 0.000 description 26
- 239000011575 calcium Substances 0.000 description 24
- 239000000843 powder Substances 0.000 description 22
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 13
- 239000010931 gold Substances 0.000 description 13
- 229910052737 gold Inorganic materials 0.000 description 13
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 12
- 229910008649 Tl2O3 Inorganic materials 0.000 description 12
- 230000004907 flux Effects 0.000 description 12
- QTQRFJQXXUPYDI-UHFFFAOYSA-N oxo(oxothallanyloxy)thallane Chemical compound O=[Tl]O[Tl]=O QTQRFJQXXUPYDI-UHFFFAOYSA-N 0.000 description 12
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 11
- 230000007717 exclusion Effects 0.000 description 11
- 238000005259 measurement Methods 0.000 description 10
- 239000000292 calcium oxide Substances 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 238000000227 grinding Methods 0.000 description 7
- 239000002243 precursor Substances 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 230000007704 transition Effects 0.000 description 6
- 229910002480 Cu-O Inorganic materials 0.000 description 5
- 239000010453 quartz Substances 0.000 description 5
- 238000012423 maintenance Methods 0.000 description 4
- 239000004570 mortar (masonry) Substances 0.000 description 4
- 238000004320 controlled atmosphere Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 239000002887 superconductor Substances 0.000 description 3
- 229910009203 Y-Ba-Cu-O Inorganic materials 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 229910014454 Ca-Cu Inorganic materials 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 230000005668 Josephson effect Effects 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- ZJRXSAYFZMGQFP-UHFFFAOYSA-N barium peroxide Chemical compound [Ba+2].[O-][O-] ZJRXSAYFZMGQFP-UHFFFAOYSA-N 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- WKMKTIVRRLOHAJ-UHFFFAOYSA-N oxygen(2-);thallium(1+) Chemical compound [O-2].[Tl+].[Tl+] WKMKTIVRRLOHAJ-UHFFFAOYSA-N 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- 229910003438 thallium oxide Inorganic materials 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F1/00—Methods of preparing compounds of the metals beryllium, magnesium, aluminium, calcium, strontium, barium, radium, thorium, or the rare earths, in general
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/45—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on copper oxide or solid solutions thereof with other oxides
- C04B35/4512—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on copper oxide or solid solutions thereof with other oxides containing thallium oxide
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/80—Constructional details
- H10N60/85—Superconducting active materials
- H10N60/855—Ceramic superconductors
- H10N60/857—Ceramic superconductors comprising copper oxide
Definitions
- This invention relates to novel
- superconducting phase has been identified as the composition La 1-x (Ba, Sr, Ca) x CuO 4-y with the tetragonal K 2 NiF 4 -type structure and with x typically about 0.15 and y indicating oxygen vacancies.
- Bi-Sr-Cu-O system A pure phase was isolated for the composition Bi 2 Sr 2 Cu 2 O 7+ ⁇ .
- the material made from ultrapure oxides has a superconducting transition with a midpoint of 22 K as determined from resistivity measurements and zero resistance below 14 K.
- the material made from commercial grade oxides has a superconducting transition with a midpoint of 7 K.
- Tl-Ba-Cu-O system in samples which have nominal compositions Tl 2 Ba 2 Cu 3 O 8 + x and TlBaCu 3 O 5 .5+x .
- the samples were prepared by mixing and grinding appropriate amounts of BaCO 3 and CuO with an agate mortar and pestle. This mixture was heated in air at 925°C for more than 24 hours with several intermediate grindings to obtain a uniform black oxide Ba-Cu oxide powder which was mixed with an appropriate amount of Tl 2 O 3 , completely ground and pressed into a pellet with a diameter of 7 mm and a thickness of 1-2 mm.
- the pellet was then put into a tube furnace which had been heated to 880-910°C and was heated for 2-5 minutes in flowing oxygen. As soon as it had slightly melted, the sample was taken from the furnace and quenched in air to room temperature. It was noted by visual inspection that Tl 2 O 3 had partially volatilized as black smoke, part had become a light yellow liquid, and part had reacted with Ba-Cu oxide forming a black, partially melted, porous material.
- Tl-Ca-Ba-Cu-O system in samples which have nominal compositions Tl 2 Ca 2 BaCu 3 O 9+x with onset of superconductivity at 120 K.
- Tl 2 Ba 2 Ca 2 Cu 3 O 10 and Tl 2 Ba 2 CaCu 2 O 8 both with onset of superconductivity near 120 K. C. C.
- Torardi et al., Science 240, 631 (1988) disclose the preparation of Tl 2 Ba 2 Ca 2 Cu 3 O 10 with an onset of superconductivity of 125 K.
- These compositions have an onset of superconductivity of at least 70 K.
- Tl:Ca:Ba:Cu in the superconductor vary from
- a is from about 2 to about 3
- b is about 4
- c is about 5
- y is from about 1/2 to about 2.
- the onset of superconductivity for these compositions is at a temperature of at least 130 K.
- These superconducting compositions can be prepared by heating a mixture of the oxides of Tl, Ca and Cu and the peroxide of Ba or a
- precursor oxide mixture prepared from these oxides the relative amounts of the oxides chosen so that the atomic ratio Tl:Ba:Ca:Cu is l:a:b:c, to a temperature of about 940°C to about 980°C, maintaining that temperature for about 5 minutes or more, said heating being carried out in a controlled atmosphere, e. g., in a sealed tube made of a non-reacting metal such as gold, which prevents any of the reactants including the metals and oxygen from escaping.
- a controlled atmosphere e. g., in a sealed tube made of a non-reacting metal such as gold, which prevents any of the reactants including the metals and oxygen from escaping.
- FIG. 1 shows a plot of the flux
- composition of this invention excluded by a composition of this invention as a function of temperature.
- the superconducting compositions of this invention can be prepared by the following process.
- a is about 2 to about 4
- b is from about 7/2 to about 5
- c is from about 9/2 to about 7
- x (a + b + c + y) where y is from about 1/2 to about 3.
- a is about 2 to about 4
- b is from about 7/2 to about 5
- c is from about 9/2 to about 7
- x (a + b + c + y) where y is from about 1/2 to about 3.
- a is about 2 to about 4
- b is from about 7/2 to about 5
- the oxide mixture can be prepared directly by choosing quantities of the oxide reactants Tl 2 O 3 , CaO and CuO and the peroxide BaO 2 such that the atomic ratio Tl:Ba:Ca:Cu is l:a:b:c and mixing them, for example, by grinding them together in a mortar.
- a precursor oxide mixture can be prepared by choosing quantities of the oxide reactants Tl 2 O 3 , CaO and CuO and the peroxide BaO 2 such that the atomic ratio
- Tl:Ba:Ca:Cu is l:a:b:c.
- the barium peroxide, calcium oxide and copper oxide are ground
- this grey mixture is then heated in an alumina crucible in a muffle furnace in air, the temperature being increased from ambient temperature, about 20°C, to about 800°C in a period of about 2 hours. The temperature is held at about 800oC for 1 hour. The sample is then cooled and the black powder is recovered. This powder is re-ground and ground together with the thallium oxide to give the precursor oxide mixture.
- the oxide mixture is then heated in a controlled atmosphere.
- a controlled atmosphere is to place the oxide mixture in a tube made of a non-reacting metal such as gold and then sealing the tube by crimping or, preferably, by welding or fusing.
- the precursor oxide mixture is less destructive of the gold tubes and is preferred for this reason.
- the sealed tube is placed in a furnace and heated to a temperature of about 940°C to about 980oC and maintained at a
- the black shiny platelets have proven to be single crystals of known materials, e. g., Tl-Ba-Ca-Cu compositions with Tl:Ba:Ca:Cu atomic ratios of 1:2:1:2 and 1:2:2:3 with lesser T c 's.
- Resistivity measurements on the as prepared ingot shows onset at about 135 K and zero resistance at about 116 K.
- the superconductivity arises from the bulk of the composition. Based on flux exclusion measurements at least 30% of each of the samples is superconducting. X-ray powder diffraction typically gives very weak lines.
- the superconducting compositions of this invention can be used to conduct current extremely efficiently or to provide a magnetic field for magnetic imaging for medical purposes.
- the composition in the form of a wire or bar can be used to conduct current extremely efficiently or to provide a magnetic field for magnetic imaging for medical purposes.
- superconducting transition temperature (T c ) in a manner well known to those in this field, and initiating a flow of electrical current, one can obtain such flow without any electrical resistive losses.
- the wire mentioned previously could be wound to form a coil which would be cooled to a temperature below the superconducting transition temperature before inducing any current into the coil.
- Such fields can be used to levitate objects as large as railroad cars.
- These superconducting compositions are also useful in Josephson devices such as SQUIDS (superconducting quantum interference devices) and in instruments that are based on the Josephson effect such as high speed sampling circuits and voltage standards.
- Flux exclusion measurements showed the onset of superconductivity at about 130 K.
- Example 2 0.456 g of Tl 2 O 3 , 1.020 g of BaO 2 , 0.448 g of CaO and 0.960 g of CuO, corresponding to a Tl:Ba:Ca:Cu atomic ratio of
- Flux exclusion measurements showed the onset of superconductivity at about 130 K.
- Examples 3 and 4 were carried out essentially as described for Example 2 except that in Example 3, 0.456 g of Tl 2 O 3 , 0.680 g of BaO 2 , 0.448 g of CaO and 0.960 g of CuO,
- Tl:Ba:Ca:Cu atomic ratio of 1:2:4:6 were ground to form a fine grey powder and in Example 4, 0.456 g of Tl 2 O 3 , 1.020 g of BaO 2 , 0.448 g of CaO and 0.800 g of CuO,
- Flux exclusion measurements showed the onset of superconductivity at about 130 K for Example 3 and at about 132 K for Example 4.
- a precursor oxide mixture was prepared by grinding together 5.10 g of BaO 2 , 2.25 g of CaO and 4.00 g of CuO. This grey mixture was then heated in an alumina crucible in a muffle furnace in air from ambient temperature, about 20°C, to 800°C in a period of 2 hours. The temperature was held at 800°C for 1 hour and then reduced to ambient. The black powder product was recovered and re-ground. The powder contained the elements Ba:Ca:Cu in the atomic ratio 3:4:5.
- this black powder was ground together with 0.456 g of Tl 2 O 3 to give a material with the atomic ratio of Tl:Ba:Ca:Cu of 1:3:4:5.
- This powder was loaded into gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0 .64 cm in diamete r ) .
- the tube was sealed at both ends by fusing and placed on an alumina boat which was placed in a horizontal quartz tube furnace.
- Heating was ca r r i ed in the following manner.
- the temperature was increased from room temperature to 700°C at a rate of about 3°C/min.
- the temperature was then increased from 700°C to 977°C at a rate of about 18.5°C/min.
- the sample cooled to 950°C over the next 5 minutes and was maintained at 950°C for 10 min.
- the sample was then cooled in the furnace to 600°C at a rate of about 10°C/min.
- the sample was then removed from the furnace and cooled to room temperature.
- the recovered material is a shiny grey-black metallic ingot with a surface
- Flux exclusion measurements showed the onset of superconductivity at about 132 K.
- a precursor oxide mixture was prepared by grinding together 1.020 g of BaO 2 , 0.448 g of CaO and 0.800 g of CuO. This grey mixture was then heated in an alumina crucible in a muffle furnace in air from ambient temperature, about 20°C, to 800°C in a period of 2 hours. The temperature was held at 800oC for 1 hour and then reduced to ambient. The black powder product was recovered and re-ground. The powder contained the elements Ba:Ca:Cu in the atomic ratio 3:4:5.
- the tube was sealed at both ends by fusing and placed on an alumina boat which was placed in a horizontal quartz tube furnace.
- Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3oC/min. The temperature was then increased from 700°C to 968°C at a rate of about 25°C/min. The sample was maintained at 968°C for 15 min. The sample was then cooled in the furnace to 600oC at a rate of about 10oC/min. The sample was then removed from the furnace and cooled to room temperature.
- the recovered material is a shiny grey-black metallic ingot with a surface
- Flux exclusion measurements showed the onset of superconductivity at about 130 K.
- Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3°C/min. The temperature was then increased from 700°C to 977°C at a rate of about 25°C/min. The sample was maintained at 977°C for 15 min. The sample was then cooled in the furnace to 600°C at a rate of about 10°C/min. The sample was then removed from the furnace and cooled to room temperature.
- the recovered material is a shiny grey-black metallic ingot with a surface
- Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3oC/min. The temperature was then increased from 700°C to a maximum temperature, T max , at a specified rate. The sample was maintained at T max for a specified time and was then cooled in the furnace to 600°C at a rate of 10°C/min except for Example 12 for which the rate was 50°C/min. The sample was then removed from the furnace and cooled to room temperature.
- the recovered material is a shiny grey-black metallic ingot with a surface
- the specified rate of heating from 700°C to T max , the temperature T max , the time for which the temperature was maintained at T max and the temperature of the onset of superconductivity are shown in Table II.
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- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Manufacturing & Machinery (AREA)
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- Geology (AREA)
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Abstract
Compositions having the nominal formula TlBaaCabCucOx, wherein a is from about 2 to 4, b is from about 7/2 to 5, c is from about 9/2 to 7, x = (a + b + c + y), where y is from about 1/2 to 3, are superconducting. Processes for manufacturing such compositions and for using them are disclosed.
Description
TITLE
SUPERCONDUCTING METAL OXIDE COMPOSITIONS
AND PROCESSES FOR MANUFACTURE AND USE
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to novel
Tl-Ba-Ca-Cu-O compositions which are
superconducting.
References
Bednorz and Muller, Z. Phys. B64, 189 (1986), disclose a superconducting phase in the La-Ba-Cu-O system with a superconducting
transition temperature of about 35 K. This disclosure was subsequently confirmed by a number of investigators [see, for example, Rao and
Ganguly, Current Science, 56, 47 (1987), Chu et al., Science 235, 567 (1987), Chu et al., Phys. Rev. Lett. 58, 405 (1987), Cava et al., Phys.
Rev. Lett. 58, 408 (1987), Bednorz et al.,
Europhys. Lett. 3, 379 (1987)]. The
superconducting phase has been identified as the composition La1-x (Ba, Sr, Ca)x CuO4-y with the tetragonal K2NiF4-type structure and with x typically about 0.15 and y indicating oxygen vacancies.
Wu et al., Phys. Rev. Lett. 58, 908 (1987), disclose a superconducting phase in the Y-Ba-Cu-O system with a superconducting
transition temperature of about 90 K. Cava et
al., Phys. Rev. Lett. 58, 1676 (1987), have identified this superconducting Y-Ba-Cu-O phase to be orthorhombic, distorted, oxygen-deficient perovskite YBa2Cu3O9-δ where δ is about 2.1.
C. Michel et al., Z. Phys. B - Condensed Matter 68, 421 (1987), disclose a novel family of superconducting oxides in the
Bi-Sr-Cu-O system. A pure phase was isolated for the composition Bi2Sr2Cu2O7+δ. The material made from ultrapure oxides has a superconducting transition with a midpoint of 22 K as determined from resistivity measurements and zero resistance below 14 K. The material made from commercial grade oxides has a superconducting transition with a midpoint of 7 K.
H. Maeda et al., Jpn. J. Appl. Phys.
27, L209 (1988), disclose a superconducting oxide in the Bi-Sr-Ca-Cu-O system with the composition near BiSrCaCu2Ox and a superconducting transition temperature of about 105 K.
The commonly assigned application,
"Superconducting Metal Oxide Compositions and Process For Making Them", S. N. 153,107, filed Feb. 8, 1988, a continuation-in-part of S. N. 152,186, filed Feb. 4, 1988, disclose
superconducting compositions having the nominal formula BiaSrbCacCu3Ox wherein a is from about 1 to about 3, b is from about 3/8 to about 4, c is from about 3/16 to about 2 and x = (1.5 a + b + c + y) where y is from about 2 to about 5, with the proviso that b + c is from about 3/2 to about 5, said compositions having superconducting
transition temperatures of about 70 K or higher. It also discloses the superconducting metal oxide phase having the formula Bi2Sr3-zCazCuzO8+w wherein z is from about 0.1 to about 0.9,
preferably 0.4 to 0.8 and w is greater than zero but less than about 1. M. A. Subramanian et al., Science 239, 1015 (1988) also disclose the
Bi2Sr3- z Caz Cu2O8 + w superconductor.
Z. Z. Sheng et al., Nature 332, 55 (1988) disclose superconductivity in the
Tl-Ba-Cu-O system in samples which have nominal compositions Tl2 Ba2 Cu3 O8 + x and TlBaCu3O5 .5+x.
Both samples are reported to have onset
temperatures above 90 K and zero resistance at 81 K. The samples were prepared by mixing and grinding appropriate amounts of BaCO3 and CuO with an agate mortar and pestle. This mixture was heated in air at 925°C for more than 24 hours with several intermediate grindings to obtain a uniform black oxide Ba-Cu oxide powder which was mixed with an appropriate amount of Tl2O3, completely ground and pressed into a pellet with a diameter of 7 mm and a thickness of 1-2 mm.
The pellet was then put into a tube furnace which had been heated to 880-910°C and was heated for 2-5 minutes in flowing oxygen. As soon as it had slightly melted, the sample was taken from the furnace and quenched in air to room temperature. It was noted by visual inspection that Tl2O3 had partially volatilized as black smoke, part had become a light yellow liquid, and part had reacted with Ba-Cu oxide forming a black,
partially melted, porous material.
Z. Z. Sheng et al., Nature 332, 138 (1988) disclose superconductivity in the
Tl-Ca-Ba-Cu-O system in samples which have nominal compositions Tl2 Ca2BaCu3O9+x with onset of superconductivity at 120 K.
R. M. Hazen et al., Phys. Rev. Lett. 60, 1657 (1988), disclose two superconducting phases in the Tl-Ba-Ca-Cu-O system,
Tl2Ba2Ca2Cu3O10 and Tl2Ba2 CaCu2O8, both with onset of superconductivity near 120 K. C. C.
Torardi et al., Science 240, 631 (1988) disclose the preparation of Tl2Ba2 Ca2 Cu3 O10 with an onset of superconductivity of 125 K.
S. S. P. Parkin et al., Phys. Rev.
Lett. 61, 750 (1988), disclose the structure
TlBa2Ca2 Cu3 O9± with transition temperatures up to 110 K.
M. Hervieu et al., J. Solid State Chem. 75, 212 (1988), disclose the oxide
TlBa2CaCu2O8-y.
C. C. Torardi et al., Phys. Rev. B 38, 225 (1988), disclose the oxide Tl2Ba2CuO6 with an onset of superconductivity at about 90 K.
The commonly assigned application, "Superconducting Metal Oxide Compositions and Processes For Manufacture and Use", S. N.
236,088, filed Aug. 24, 1988, a
continuation-in-part of S. N. 230,636, filed Aug. 10, 1988, disclose superconducting compositions having the nominal formula Tle Pba Cab Src CudOx wherein a is from about 1/10 to about 3/2, b is
from about 1 to about 4, c is from about 1 to about 3, d is from about 1 to about 5, e is from about 3/10 to about 1 and x = (a + b + c + d + e +y) where y is from about 1/2 to about 3. These compositions have an onset of superconductivity of at least 70 K.
Numerous papers have appeared relating to the above compositions. The highest transition temperature reported for any of the above compositions at this time is 125 K for Tl2 Ba2 Ca2 Cu3 Ox as disclosed by S. S. P. Parkin et al., Phys. Rev. Lett. 60, 2539 (1988)
J. M. Liang et al., Appl. Phys. Lett. 53, 15 (1988) disclose a composition
TlBa2 Ca3 Cu4 Ox with an onset of superconductivity at 155 K and a zero resistance at 123 K. CaCO3, BaCO3 and CuO powders were ground together and calcined for 15 hours with intermediate
grindings. The Ba-Ca-Cu-O powders were mixed with Tl2O3 to yield a mixture with nominal composition TlBaCa3 Cu3 Ox. This mixture was ground, pressed and sintered for 15 minutes in flowing O2. Composition ratios of the
Tl:Ca:Ba:Cu in the superconductor vary from
1:2:2:3 to 1:2:3:4.
SUMMARY OF THE INVENTION
This invention provides novel superconducting compositions having the nominal formula TlBaa Cab Cuc Ox wherein a is from about
2 to about 4, b is from about 7/2 to about 5, c is from about 9/2 to about 7 and x = (a + b + c + y) where y is from about 1/2 to about 3.
Preferably, a is from about 2 to about 3, b is about 4, c is about 5, and y is from about 1/2 to about 2. The onset of superconductivity for these compositions is at a temperature of at least 130 K.
These superconducting compositions can be prepared by heating a mixture of the oxides of Tl, Ca and Cu and the peroxide of Ba or a
precursor oxide mixture prepared from these oxides, the relative amounts of the oxides chosen so that the atomic ratio Tl:Ba:Ca:Cu is l:a:b:c, to a temperature of about 940°C to about 980°C, maintaining that temperature for about 5 minutes or more, said heating being carried out in a controlled atmosphere, e. g., in a sealed tube made of a non-reacting metal such as gold, which prevents any of the reactants including the metals and oxygen from escaping.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plot of the flux
excluded by a composition of this invention as a function of temperature.
DETAILED DESCRIPTION OF THE INVENTION
The superconducting compositions of this invention can be prepared by the following process. The oxide mixture used in this process is prepared so that the atomic ratio Tl:Ba:Ca:Cu
is l:a:b:c wherein a is from about 2 to about 4, b is from about 7/2 to about 5, c is from about 9/2 to about 7 and x = (a + b + c + y) where y is from about 1/2 to about 3. Preferably, a is about 2, b is about 4, c is about 5, and y is from about 1/2 to about 2.
The oxide mixture can be prepared directly by choosing quantities of the oxide reactants Tl2O3, CaO and CuO and the peroxide BaO2 such that the atomic ratio Tl:Ba:Ca:Cu is l:a:b:c and mixing them, for example, by grinding them together in a mortar.
Alternatively, a precursor oxide mixture can be prepared by choosing quantities of the oxide reactants Tl2O3, CaO and CuO and the peroxide BaO2 such that the atomic ratio
Tl:Ba:Ca:Cu is l:a:b:c. The barium peroxide, calcium oxide and copper oxide are ground
together and this grey mixture is then heated in an alumina crucible in a muffle furnace in air, the temperature being increased from ambient temperature, about 20°C, to about 800°C in a period of about 2 hours. The temperature is held at about 800ºC for 1 hour. The sample is then cooled and the black powder is recovered. This powder is re-ground and ground together with the thallium oxide to give the precursor oxide mixture.
The oxide mixture is then heated in a controlled atmosphere. One convenient way to accomplish a controlled atmosphere is to place the oxide mixture in a tube made of a
non-reacting metal such as gold and then sealing the tube by crimping or, preferably, by welding or fusing. The precursor oxide mixture is less destructive of the gold tubes and is preferred for this reason. The sealed tube is placed in a furnace and heated to a temperature of about 940°C to about 980ºC and maintained at a
temperature in this range, i. e., about 940°C to about 980°C, for about 5 minutes or more.
Maintaining the sample at such a temperature for 5 minutes is sufficient to form the
superconductor of the invention when the sample is heated from 700°C to a temperature in the prescribed range at a rate of 50ºC/min and subsequently cooled at a rate of 10°C/min to 600°C. Faster heating and cooling rates may require somewhat longer maintenance times.
Maintenance times of up to an hour or more can be used but corrosion of the gold tube becomes evident at about that time and maintenance times of about 5 to about 60 minutes are typical. The sample is then cooled to ambient temperature and the shiny grey-black metallic-appearing ingot recovered. During the thermal cycle the gold tube typically bloats; however, at the end of the procedure there is not excess pressure in the tube when it is cut open. The recovered material is a shiny grey/black
metallic ingot with a surface bejeweled with black shiny platelets. The black shiny platelets have proven to be single crystals of known materials, e. g., Tl-Ba-Ca-Cu compositions with
Tl:Ba:Ca:Cu atomic ratios of 1:2:1:2 and 1:2:2:3 with lesser Tc's.
Flux exclusion measurements on the compositions of this invention, prepared as described above, show an onset of
superconductivity at about 130-132 K.
Resistivity measurements on the as prepared ingot shows onset at about 135 K and zero resistance at about 116 K. The superconductivity arises from the bulk of the composition. Based on flux exclusion measurements at least 30% of each of the samples is superconducting. X-ray powder diffraction typically gives very weak lines.
Longer maintenance times at the maximum heating temperature have produced samples which show discrete x-ray lines. The 22 A (2.2 nm) c axis which is observed in the powder diffraction pattern is what is calculated for a 1245
(Tl:Ba:Ca:Cu atomic ratio) phase using a formula of Ihara et al., Nature 334, 510 (1988).
Electron microscopy results have shown
intergrowth of layered phases including a 1245 phase.
Superconductivity can be confirmed by observing magnetic flux exclusion, i.e., the Meissner effect. This effect can be measured by the method described in an article by E. Polturak and B. Fisher in Physical Review B, 36,
5586(1987).
The superconducting compositions of this invention can be used to conduct current extremely efficiently or to provide a magnetic
field for magnetic imaging for medical purposes. Thus, by cooling the composition in the form of a wire or bar to a temperature below the
superconducting transition temperature, (Tc), in a manner well known to those in this field, and initiating a flow of electrical current, one can obtain such flow without any electrical resistive losses. To provide exceptionally high magnetic fields with minimal power losses, the wire mentioned previously could be wound to form a coil which would be cooled to a temperature below the superconducting transition temperature before inducing any current into the coil. Such fields can be used to levitate objects as large as railroad cars. These superconducting compositions are also useful in Josephson devices such as SQUIDS (superconducting quantum interference devices) and in instruments that are based on the Josephson effect such as high speed sampling circuits and voltage standards.
EXAMPLES OF THE INVENTION
EXAMPLE 1 0.456 g of Tl2O3, 1.020 g of BaO2,
0.448 g of CaO and 0.960 g of CuO, corresponding to a Tl:Ba:Ca:Cu atomic ratio of 1:3:4:6, were ground together in an agate mortar for about 3 minutes to form a fine grey powder. This powder was loaded into a gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0.64 cm
in diameter) and the gold tube was crimped shut. The tube was placed in a quartz tube furnace and heated in a slow oxygen flow in the following manner. The tube was heated from ambient
temperature, about 20ºC, to 700ºC at a rate of about 3ºC/min and then from 700ºC to 977ºC in ten minutes. Over the next five minutes the
temperature decreased to 950°C. Power to the furnace was then shut off and the tube was allowed to cool to room temperature in the furnace. The tube was then removed from the furnace and cut open. The grey-black ingot product was recovered.
Flux exclusion measurements showed the onset of superconductivity at about 130 K.
EXAMPLES 2-4
In Example 2 , 0.456 g of Tl2O3, 1.020 g of BaO2, 0.448 g of CaO and 0.960 g of CuO, corresponding to a Tl:Ba:Ca:Cu atomic ratio of
1:3:4:6, were ground together in an agate mortar for about 3 minutes to form a fine grey powder. This powder was loaded into a gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0.64 cm in diameter) and the gold tube was crimped shut. The tube was placed in a quartz tube furnace and heated in a slow oxygen flow in the following manner. The tube was heated from ambient temperature, about 20°C, to 700°C at a rate of about 3°C/min and then from 700°C to 950°C at a rate of about 25°C/min. The
temperature was maintained at 950°C for 5 min and then cooled to 600ºC at a rate of about 10°C/min. Power to the furnace was then shut off and the tube was allowed to cool to room temperature in the furnace. The tube was then removed from the furnace and cut open. The grey-black ingot product was recovered.
Flux exclusion measurements showed the onset of superconductivity at about 130 K.
Examples 3 and 4 were carried out essentially as described for Example 2 except that in Example 3, 0.456 g of Tl2O3, 0.680 g of BaO2, 0.448 g of CaO and 0.960 g of CuO,
corresponding to a Tl:Ba:Ca:Cu atomic ratio of 1:2:4:6, were ground to form a fine grey powder and in Example 4, 0.456 g of Tl2O3, 1.020 g of BaO2, 0.448 g of CaO and 0.800 g of CuO,
corresponding to a Tl:Ba:Ca:Cu atomic ratio of 1:3:4:5, were ground together to form a fine grey powder.
Flux exclusion measurements showed the onset of superconductivity at about 130 K for Example 3 and at about 132 K for Example 4.
EXAMPLE 5
A precursor oxide mixture was prepared by grinding together 5.10 g of BaO2, 2.25 g of CaO and 4.00 g of CuO. This grey mixture was then heated in an alumina crucible in a muffle furnace in air from ambient temperature, about 20°C, to 800°C in a period of 2 hours. The
temperature was held at 800°C for 1 hour and then reduced to ambient. The black powder product was recovered and re-ground. The powder contained the elements Ba:Ca:Cu in the atomic ratio 3:4:5.
2.30 g of this black powder was ground together with 0.456 g of Tl2O3 to give a material with the atomic ratio of Tl:Ba:Ca:Cu of 1:3:4:5. This powder was loaded into gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0 .64 cm in diamete r ) . The tube was sealed at both ends by fusing and placed on an alumina boat which was placed in a horizontal quartz tube furnace.
Heating was ca r r i ed in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3°C/min. The temperature was then increased from 700°C to 977°C at a rate of about 18.5°C/min. The sample cooled to 950°C over the next 5 minutes and was maintained at 950°C for 10 min. The sample was then cooled in the furnace to 600°C at a rate of about 10°C/min. The sample was then removed from the furnace and cooled to room temperature.
The recovered material is a shiny grey-black metallic ingot with a surface
bejeweled with black shiny platelets.
Flux exclusion measurements showed the onset of superconductivity at about 132 K.
EXAMPLE 6
A precursor oxide mixture was prepared
by grinding together 1.020 g of BaO2 , 0.448 g of CaO and 0.800 g of CuO. This grey mixture was then heated in an alumina crucible in a muffle furnace in air from ambient temperature, about 20°C, to 800°C in a period of 2 hours. The temperature was held at 800ºC for 1 hour and then reduced to ambient. The black powder product was recovered and re-ground. The powder contained the elements Ba:Ca:Cu in the atomic ratio 3:4:5.
2.300 g of this black powder was ground together with 0.342 g of Tl2O3 to give a material with the atomic ratio of Tl:Ba:Ca:Cu of
0.75:3:4:5 which, rounded off to integers, is approximately 1:4:5:7. This powder was loaded into gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0.64 cm in
diameter). The tube was sealed at both ends by fusing and placed on an alumina boat which was placed in a horizontal quartz tube furnace.
Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3ºC/min. The temperature was then increased from 700°C to 968°C at a rate of about 25°C/min. The sample was maintained at 968°C for 15 min. The sample was then cooled in the furnace to 600ºC at a rate of about 10ºC/min. The sample was then removed from the furnace and cooled to room temperature.
The recovered material is a shiny grey-black metallic ingot with a surface
bejeweled with black shiny platelets.
Flux exclusion measurements showed the
onset of superconductivity at about 130 K.
EXAMPLE 7
An oxide mixture containing the
elements Ba:Ca:Cu in the atomic ratio of 3:4:5 was prepared essentially as described in Example 6.
2.300 g of this black powder was ground together with 0.456 g of Tl2O3 to give a material with the atomic ratio of Tl:Ba:Ca:Cu of 1:3:4:5. This powder was loaded into gold tube, about 3 inches long and 1/4 inch in diameter (7.6 cm long and 0.64 cm in diameter). The tube was sealed at both ends by fusing and placed on an alumina boat which was placed in a horizontal quartz tube furnace.
Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3°C/min. The temperature was then increased from 700°C to 977°C at a rate of about 25°C/min. The sample was maintained at 977°C for 15 min. The sample was then cooled in the furnace to 600°C at a rate of about 10°C/min. The sample was then removed from the furnace and cooled to room temperature.
The recovered material is a shiny grey-black metallic ingot with a surface
bej eweled wi th black shiny platelets .
This Example was essentially repeated several times and the products were essentially identical.
Flux exclusion measurements were carried out on one of these products and the results are shown in Fig. 1 where the flux exclusion is plotted as a function of
temperature. The plot shows the onset of
superconductivity at about 132 K.
X-ray diffraction was carried out on a powder obtained by grinding one of these
products. The d-spacings, the relative
intensities and the indices of a set of observed reflections of the X-ray powder diffraction pattern which are always present when onset of superconductivity is observed at a temperature of 130 K or above is shown in Table I.
EXAMPLE 8-13
In each of these Examples a precursor oxide mixture containing the elements Tl:Ba:Ca:Cu in the atomic ratio of 1:3:4:5 was prepared, placed in a gold tube and then placed in a furnace essentially as described in Example 5.
Heating was carried in the following manner. The temperature was increased from room temperature to 700°C at a rate of about 3ºC/min. The temperature was then increased from 700°C to a maximum temperature, Tmax, at a specified rate. The sample was maintained at Tmax for a specified time and was then cooled in the furnace to 600°C at a rate of 10°C/min except for Example 12 for which the rate was 50°C/min. The sample was then removed from the furnace and cooled to room temperature.
The recovered material is a shiny grey-black metallic ingot with a surface
bejeweled with black shiny platelets.
Flux exclusion measurements were carried out on each product.
Claims
1. A superconducting composition having the nominal formula
TlBaa Cab Cuc Ox
wherein a is from about 2 to about 4,
b is from about 7/2 to about 5, c is from about 9/2 to about 7, x = (a + b + c + y) where
y is from about 1/2 to about 3,
said composition having an onset of
superconducting at a temperature of at least 130 K.
2. A superconducting composition as in Claim 1 wherein "a" is from about 2 to about 3, "b" is about 4, "c" is about 5 and "y" is from about 1/2 to about 2.
3. A superconductivity composition as in Claim 2 wherein "a" is about 2.
4. A process for making
superconducting compositions consisting
essentially of mixing stoichiometric quantities of oxides of T1, Ca and Cu and the peroxide of Ba to provide the composition of Claim 1; heating the mixture in a confined atmosphere to a
temperature of about 940°C to about 980°C and maintaining said temperature for about 5 minutes or more; and cooling said composition.
5. A process as in Claim 4 wherein the stoichiometric quantities of the oxides are selected to provide the composition of Claim 3.
6. The process of Claim 4 wherein the oxides of Ca and Cu and the peroxide of Ba are mixed, heated to about 800°C, ground and mixed with the T1 oxide to provide the mixture to be heated.
7. The process of Claim 5 wherein the oxides of Ca and Cu and the peroxide of Ba are mixed, heated to about 800ºC, ground and mixed with the T1 oxide to provide the mixture to be heated.
8. A method for conducting an electrical current within a conductor material without electrical resistive losses comprising the steps of:
cooling a conductor material composed of a composition of Claim 1 to a temperature below the T of said composition;
initiating a flow of electrical current within said conductor material while
maintaining said material below said
temperature.
9. A method as in Claim 8 wherein said conductor material is cooled to a temperature from 77K to Tc of said composition.
10. An improved Josephson-effeet device wherein the superconductive material comprises the composition of Claim 1.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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JP90503500A JPH04501553A (en) | 1988-11-02 | 1989-10-16 | Superconducting metal oxide compositions and manufacturing methods and uses |
KR1019900701396A KR900701659A (en) | 1988-11-02 | 1989-10-16 | Superconducting Metal Oxidizing Compositions and Methods of Preparation and Use |
DK072091A DK72091A (en) | 1988-11-02 | 1991-04-19 | SUPERVISORY COMPOSITION, ITS MANUFACTURING AND USE |
NO911667A NO911667D0 (en) | 1988-11-02 | 1991-04-26 | SUPERVISIVE METAL OXYDE COMPOSITIONS AND PROCEDURES FOR MANUFACTURING AND USING. |
Applications Claiming Priority (2)
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US26618088A | 1988-11-02 | 1988-11-02 | |
US266,180 | 1988-11-02 |
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EP (1) | EP0441903A4 (en) |
JP (1) | JPH04501553A (en) |
KR (1) | KR900701659A (en) |
AU (1) | AU5096990A (en) |
CA (1) | CA2002022A1 (en) |
DK (1) | DK72091A (en) |
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WO (1) | WO1990005384A1 (en) |
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DE68909945T2 (en) * | 1988-08-10 | 1994-03-03 | Du Pont | SUPRA-CONDUCTING METAL OXIDE COMPOSITIONS AND METHOD FOR THE PRODUCTION THEREOF. |
JPH07138019A (en) * | 1993-11-16 | 1995-05-30 | Nec Corp | Production of thallium-based oxide superconductor |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US4412902A (en) * | 1981-06-22 | 1983-11-01 | Nippon Telegraph & Telephone Public Corporation | Method of fabrication of Josephson tunnel junction |
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1989
- 1989-10-16 EP EP19900903287 patent/EP0441903A4/en not_active Withdrawn
- 1989-10-16 JP JP90503500A patent/JPH04501553A/en active Pending
- 1989-10-16 AU AU50969/90A patent/AU5096990A/en not_active Abandoned
- 1989-10-16 WO PCT/US1989/004477 patent/WO1990005384A1/en not_active Application Discontinuation
- 1989-10-16 KR KR1019900701396A patent/KR900701659A/en not_active Application Discontinuation
- 1989-11-01 CA CA002002022A patent/CA2002022A1/en not_active Abandoned
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1991
- 1991-04-19 DK DK072091A patent/DK72091A/en not_active Application Discontinuation
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4412902A (en) * | 1981-06-22 | 1983-11-01 | Nippon Telegraph & Telephone Public Corporation | Method of fabrication of Josephson tunnel junction |
Non-Patent Citations (4)
Title |
---|
Modern Physics Letters B, Volume 2, Number 9, October 1988, POLITIS et al, "Is the Magnetic Suspension of High-Temperature Superconductors a general phenomennon?", pages 1119-1123. * |
Nature, Volume 334, 11 August 1988, IHARA et al, "A new high-Tc T1Ba2 Ca3 Cu4 0 Su-perconductor with Tc 120K", pages 510-511. * |
Science, Volume 241, 02 September 1988, HALDAR et al, "Bulk Superconductivity at 122K in T1 (Ba1 Ca) 2 Ca3 Cu4 OX with Four consecutive Copper Layers", pages 1198-1200. * |
See also references of EP0441903A4 * |
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DK72091D0 (en) | 1991-04-19 |
AU5096990A (en) | 1990-05-28 |
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EP0441903A1 (en) | 1991-08-21 |
KR900701659A (en) | 1990-12-04 |
DK72091A (en) | 1991-04-19 |
JPH04501553A (en) | 1992-03-19 |
EP0441903A4 (en) | 1991-12-04 |
CA2002022A1 (en) | 1990-05-02 |
NO911667D0 (en) | 1991-04-26 |
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