AU5167790A - Process for making superconducting metal oxide compositions - Google Patents
Process for making superconducting metal oxide compositionsInfo
- Publication number
- AU5167790A AU5167790A AU51677/90A AU5167790A AU5167790A AU 5167790 A AU5167790 A AU 5167790A AU 51677/90 A AU51677/90 A AU 51677/90A AU 5167790 A AU5167790 A AU 5167790A AU 5167790 A AU5167790 A AU 5167790A
- Authority
- AU
- Australia
- Prior art keywords
- solid
- heating
- temperature
- superconducting
- powder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims description 24
- 239000000203 mixture Substances 0.000 title description 21
- 229910044991 metal oxide Inorganic materials 0.000 title description 4
- 150000004706 metal oxides Chemical class 0.000 title description 4
- 239000000843 powder Substances 0.000 claims description 31
- 239000007787 solid Substances 0.000 claims description 31
- 239000002243 precursor Substances 0.000 claims description 30
- 238000010438 heat treatment Methods 0.000 claims description 23
- 239000012071 phase Substances 0.000 claims description 20
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 150000002823 nitrates Chemical class 0.000 claims description 11
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 238000010791 quenching Methods 0.000 claims description 9
- 230000000171 quenching effect Effects 0.000 claims description 9
- 229910052684 Cerium Inorganic materials 0.000 claims description 8
- 229910052779 Neodymium Inorganic materials 0.000 claims description 8
- 229910052772 Samarium Inorganic materials 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 8
- 230000008020 evaporation Effects 0.000 claims description 8
- 238000000227 grinding Methods 0.000 claims description 8
- 238000001694 spray drying Methods 0.000 claims description 8
- 239000008346 aqueous phase Substances 0.000 claims description 7
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000010949 copper Substances 0.000 description 16
- 239000008188 pellet Substances 0.000 description 12
- 230000007704 transition Effects 0.000 description 8
- 230000004907 flux Effects 0.000 description 6
- 230000007717 exclusion Effects 0.000 description 5
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000007788 liquid Substances 0.000 description 3
- 238000003746 solid phase reaction Methods 0.000 description 3
- 238000010671 solid-state reaction Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910004247 CaCu Inorganic materials 0.000 description 1
- 229910002480 Cu-O Inorganic materials 0.000 description 1
- 230000005668 Josephson effect Effects 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- BQXQGZPYHWWCEB-UHFFFAOYSA-N carazolol Chemical compound N1C2=CC=CC=C2C2=C1C=CC=C2OCC(O)CNC(C)C BQXQGZPYHWWCEB-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000005493 condensed matter Effects 0.000 description 1
- 238000001816 cooling Methods 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
- 230000007423 decrease Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000002524 electron diffraction data Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000003836 solid-state method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
-
- 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
- C04B35/4504—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 rare earth oxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G3/00—Compounds of copper
- C01G3/006—Compounds containing, besides copper, two or more other elements, with the exception of oxygen or hydrogen
-
- 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
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
-
- 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
- H10N60/01—Manufacture or treatment
- H10N60/0268—Manufacture or treatment of devices comprising copper oxide
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Ceramic Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
Description
TITLE
PROCESS FOR MAKING SUPERCONDUCTING
METAL OXIDE COMPOSITIONS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to processes for making superconducting rare earth-cerium-copper- oxygen compositions and precursors thereof.
References
Bednorz and Muller, Z. Phys. B64, 189 (1986), disclose a superconducting phase in the La-Ba-Cu-0 system with a superconducting transition temperature of about 35 K. The superconducting phase has been identified as the composition La._χ (Ba,Sr,Ca)χCu04_ with the tetragonal K.NiF4-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-0 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-0 phase to be orthorhombic, distorted, oxygen-deficient perovskite YBa_Cu.09_. where δ is about 2.1 and present the powder x-ray diffraction pattern and lattice parameters.
C. Michel et al. , Z. Phys. B -
Condensed Matter 68, 421 (1987), disclose a novel family of superconducting oxides in the Bi-Sr-Cu-0 system with composition close to Bi2Sr.Cu.07+.. A pure phase was isolated for the composition Bi.Sr.Cu_07+ s . The X-ray diffraction pattern for this material exhibits some similarity with that of perovskite and the electron diffraction pattern shows the perovskite subcell with the orthorhombic cell parameters of a - 5.32 A (0.532 nm), b - 26.6 A (2.66 nm) and c - 48.8 A (4.88 nm) . 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-0 system with the composition near BiSrCaCu.Ox 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 BiaSrbCacCu_Oχ 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 p rhase having3 the formula Bi2.Sr3,- zCa_Cu2,0.8 +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 Bi. ._Sr,_J — zCazCu,__0o_+ w sup*■erconductor.
Y. Yumada et al. , Jpn. J. Appl. Phys. 27, L996 (1988), disclose the substitution of Pb for Bi in the series Bi1_χPbχSrCaCu.0 where x - 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0. The Tc increases from 75.5 K for x - 0, no Pb present, to a maximum of 85.5 K for x ■ 0.5. T decreases for higher Pb content to 76 K for x » 0.7. No superconductivity was observed for the samples with x « 0.9 and x - 1.
Z. Z. Sheng et al. , Nature 332, 55 (1988) disclose superconductivity in the Tl-Ba-Cu-O system in samples which have nominal compositions Tl.Ba.Cu,0,^ and TlBaCu,0. _ Both samples are reported to have onset temperatures above 90 K and zero resistance at 81 K.
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 Tl Ca.BaCu309+χ 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,
Tl.Ba.Ca.Cu.O.0 and Tl.Ba.CaCu.Og , both with onset of superconductivity near 120 K. C. C. Torardi et al., Science 240, 631 (1988) disclose the preparation of Tl.Ba.Ca.Cu.O.0 with an onset of superconductivity of 125 K.
S. S. P. Parkin et al., Phys. Rev.
Lett. 61, 750 (1988), disclose the structure TlBa. Ca_ Cu.Og+ „ with transition temperatures up to 110 K.
M. Hervieu et al., J. Solid State Chem. 75, 212 (1988), disclose the oxide
TlBa.CaCu.08_y •
C. C. Torardi et al., Phys. Rev. B 38, 225 (1988), disclose the oxide Tl 2,Ba 2„ CuOo, 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 3 the nominal formula TlePbaCa.bSrcCud.Ox 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.
J. M. Liang et al., Appl. Phys. Lett. 53, 15 (1988) disclose a composition
TlBa. Ca. Cu4Oχ with an onset of superconductivity at 155 K and a zero resistance at 123 K.
J. Akimitsu et al . , Jpn. J. Appl. Phys. 27, L1859 (1988), disclose superconductivity in the Nd-Sr-Ce-Cu-0 system with an onset of superconductivity at about 28 K. E. Takayama- Muro achi et al., Jpn. J. Appl. Phys. 27, L2283 (1988), report that the superconducting phase has the formula (Nd0 6 ,Ce0 . , _ Sr0 .0 _ ). CuOy .
All of the superconducting oxides discussed above exhibit hole conduction. In contrast, Y. Tokura et al . , Nature 337, 345 (1989) disclose a superconducting oxide with the formula Ln._χCeχCu04 , where Ln is Pr, Nd or Sm, which exhibits electron conducton. The composition with x - 0.15 and y - 0.07 has a transition temperature of 24 K. The superconducting materials were synthesized from a mixture of rare earth metal oxides (CeO i, , Pro,0i, ,l, Nd.03 , Sm203) and CuO. The powder mixture was calcined in air at 950°C for 10 hours, pressed into pellets and sintered in air at 1150°C for 12 hours. The samples were quenched in air to room temperature and then annealed for 10 hours under reducing conditions - at 1000°C in a stream of Ar/O. gas with the oxygen partial pressure less than 10" 3 atm - and quenched to room temperature in the same atmosphere. Best results were obtained with an oxygen partial pressure of about 8xl0~5 atm.
Results obtained when trying to reproduce the solid state reaction described by Y. Tokura et al., Nature 337, 345 (1989), were inconsistent and the portion of the sample exhibiting superconductivity often small. An object of this invention is to provide a process which results in readily reproducible results and well-sintered shaped articles.
SUMMARY OF THE INVENTION
This invention provides a process for preparing the superconducting phase with the formula Ln, 2 - xCexCuO.. - y , where Ln is Pr,' Nd or Sm, x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting
essentially of
(a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l,
(b) removing the aqueous phase from the solution thereby obtaining a powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying, (c) heating said powder or a shaped article formed from said powder to a temperature from about 950°C to about 1100°C in air for about 24 hours to about 48 hours and then quenching to room temperature, (d) heating the reducible precursor in a reducing atmosphere to a temperature from about 850βC to about 1000βC for about 12 or more hours and then quenching while still in the reducing atmosphere to room temperature to produce the superconducting phase.
Preferably x is 0.15.
This invention also provides processes for forming precursors to the superconducting phase with the formula Ln._χCeχCu04_ , where Ln is Pr, Nd or Sm, x is from about 0.14 to about 0.16 and y is greater than about 0.06, the precursors being the precursor powder obtained by practicing steps (a) and (b) of the above process and the reducible precursor obtained by practicing steps (a), (b) and (c) of the above process.
BRIEF DESCRIPTION OF THE DRAWING
The Figure is a plot of the flux excluded as a function of temperature for a composition prepared by the process of the invention and one prepared by the solid state reaction of the art.
DETAILED DESCRIPTION OF THE INVENTION
This invention provides a process for preparing superconducting oxide phases in the rare earth-cerium-copper system, said process consisting essentially of
(a) forming an aqueous solution of nitrates of the rare earth, Ce and Cu with the atomic ratio of rare earth:Ce:Cu being that required by the phase,
(b) removing the aqueous phase from the solution thereby obtaining a powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying,
(c) heating said powder or a shaped article formed from said powder to a temperature from about 950°C to about 1100°C for about 24 hours to about 48 hours and then quenching in air to room temperature,
(d) heating the reducible precursor in a reducing atmosphere at a temperature from about 850°C to about 1000°C for about 12 or more hours and then quenching while still in the reducing atmosphere to room temperature to produce the superconducting phase.
The aqueous solution of nitrates of Ln, Ce and Cu can be prepared by starting with the appropriate nitrate salts. Alternatively, the
aqueous solution of nitrates can be prepared by reacting one or more of the metal oxides such as Ln.0. , CeO. and CuO with sufficient concentrated nitric acid to convert the metals present to nitrates. Excess concentrated nitric acid can be used to speed the reaction. The amount of concentrated nitric acid used is typically between one and two times the amount needed to convert all the metals present to metal nitrates. Solids present in the solution can be dissolved by adding additional water or warming the solution.
The solvent can be removed from the solution by boiling to form a solid. Preferably, the evaporation is carried out slowly. The solid formed is heated to a temperature of about 400°C to about 650°C. The resulting black solid produced is ground to form a precursor powder. Alternatively, the solvent can be removed from the solution by spray drying to directly produce a precursor powder.
The precursor powder or a shaped article formed from the precursor powder is heated to a temperaure from about 950°C to about 1100°C in air for about 24 hours to about 48 hours and then quenched in air to room temperature to form a reducible precursor.
The reducible precursor can be converted to the superconducting composition by heating in a reducing atmosphere at a temperature from about 850°C to about 1000°C for about 12 hours or more and then quenching while still in the reducing atmosphere to produce the superconducting phase. Preferably, the reducing atmosphere is flowing argon.
This invention also includes a process for forming a precursor to the superconducting p rhase with the formula Ln2,- xCexCuO4,- y , where Ln is Pr, Nd or Sm, x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting essentially of
(a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l,
(b) removing the aqueous phase from the solution to obtain a precursor powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying. This invention also includes a process for forming a reducible precursor to the superconducting phase with the formula Ln._χCeχCu04 , where Ln is Pr, Nd or Sm, x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting essentially of
(a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l, (b) removing the aqueous phase from the solution to obtain a precursor powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying,
(c) heating said precursor powder or a shaped article formed from said precursor powder to a temperature from about 950°C to about 1100°C in air for about 24 hours to about 48 hours and
then quenching to room temperature to form a reducible precursor.
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, (T ), 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, i. e., using liquid helium, 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
To a beaker containing a mixture consisting of 3.1124 g of Nd.0. , 0.8223 g of (NH4 ).Ce(N0. ), and 0.7954 g of CuO, corresponding to a Nd:Ce:Cu atomic ratio of 1.85:0.15:1, were added 10 mL concentrated nitric acid and 30 mL of water. The mixture was heated to a temperature maintained in the range between 90°C and 100°C to dissolve the solids. The resulting clear, i.e., no solids present, green solution was heated to evaporate some solvent and form a syrupy liquid. The syrupy liquid was transferred to a platinum dish and heated slowly to dryness. The solid precursor formed was heated at a temperature of 600°C for 2 hours. The black solid was removed from the platinum dish and ground in an agate mortar to form a precursor powder. The pr-ecursor powder was pressed into a pellet, 10 mm in diameter and about 3 mm thick. The pellet was heated at 1100°C in air for 24 hours and then quenched to room temperature in air. The pellet was then heated in flowing argon at 900βC for about 24 hours and then quenched to room temperature while still in the flowing argon.
The pellet was crushed into powder and the results of flux exclusion measurements are shown in the Figure. It should be noted that the sample is superconducting at 20 K. Also shown in the Figure are the results of flux exclusion measurements on powder prepared as described in the Experiment below by the solid state method of the art. The amount of flux exclusion by the
sample of the invention is nearly ten times that of the solid state sample, thereby indicating considerably more superconducting phase present in the sample of the invention as compared to the solid state sample.
EXPERIMENT A
A solid state reaction was carried out to prepare marterial with the same composition as that prepared in the Example. A mixed powder was prepared by grinding 12.4496 g of Nd.O. , 1.0328 g of CeO. and 3.1816 g of CuO in an agate mortar. A portion of this powder was pressed into a pellet, 10 mm in diameter and about 3 mm thick. The remaining powder and the pellet were heated at 950°C in air for 10 hours. The powder was pressed into a pellet, 10 mm in diameter and about 3 mm thick. Both pellets were heated at 1150°C in air for 12 hours. The pellets were quenched in air to room temperature. The pellets were then heated in flowing argon at 900°C for about 24 hours and then quenched to room temperature while still in the flowing argon. The pellets were crushed into powders and the flux exclusion measurements showed similar results.
Claims (6)
1. A process for preparing a superconducting phase with the formula
Ln 2,- xCexCuO4, - y ,' where Ln is Pr,' Nd or Sm,' x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting essentially of (a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l,
(b) removing the aqueous phase from the solution thereby obtaining a powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying,
(c) heating said powder or a shaped article formed from said powder to a temperature from about 950°C to about 1100°C in air for about 24 hours to about 48 hours and then quenching to room temperature, and
(d) heating the reducible precursor in a reducing atmosphere to a temperature from about
850°C to about 1000°C for about 12 or more hours and then quenching while still in the reducing atmosphere to room temperature to produce the superconducting phase.
2. The process of Claim 1 wherein x is about 0.15.
3. The process of Claim 1 wherein the reducing atmosphere consists essentially of argon.
The process of Claim 1 wherein Ln is Nd.
5. A process for forming a precursor to a superconducting phase with the formula
Ln, 2- CexCuO4.-y , where Ln is Pr, Nd or Sm,' x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting essentially of
(a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l, and
(b) removing the aqueous phase from the solution to obtain the precursor powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying.
6. A process for forming a reducible precursor to the superconducting phase with the formula Ln._χCeχCu04 , where Ln is Pr, Nd or Sm, x is from about 0.14 to about 0.16 and y is greater than about 0.06, said process consisting essentially of
(a) forming an aqueous solution of nitrates of Ln, Ce and Cu with the atomic ratio of Ln:Ce:Cu being (2-x):x:l,
(b) removing the aqueous phase from the solution to obtain the precursor powder either by evaporation by heating to form a solid, then heating said solid to a temperature of about 400°C to about 650°C and then grinding the solid, or by spray drying, and
(c) heating the precursor powder or a shaped article formed from the precursor powder to a temperature from about 950°C to about 1100°C in air for about 24 hours to about 48 hours and then quenching to room temperature to form the reducible precursor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31420089A | 1989-02-23 | 1989-02-23 | |
| US314200 | 1989-02-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AU5167790A true AU5167790A (en) | 1990-09-26 |
Family
ID=23218992
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU51677/90A Abandoned AU5167790A (en) | 1989-02-23 | 1990-02-20 | Process for making superconducting metal oxide compositions |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH04503657A (en) |
| KR (1) | KR920701046A (en) |
| AU (1) | AU5167790A (en) |
| CA (1) | CA2010615A1 (en) |
| WO (1) | WO1990009961A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4244723C2 (en) * | 1992-01-27 | 1995-09-07 | Roth Technik Gmbh | Oxygen sensor based on complex metal oxides |
| JP2021075408A (en) * | 2019-11-05 | 2021-05-20 | セイコーエプソン株式会社 | Producing method of solid composition and functional ceramic |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1398143A (en) * | 1972-07-18 | 1975-06-18 | Square D Co | Electrical contact materials |
| JPS5137918B2 (en) * | 1974-07-10 | 1976-10-19 | ||
| US4231997A (en) * | 1979-04-05 | 1980-11-04 | Engelhard Minerals & Chemicals Corporation | Preparation of rare earth nitrates |
| FR2578240B1 (en) * | 1985-03-01 | 1987-04-17 | Rhone Poulenc Spec Chim | NEODYME TITANATE AND BARIUM TITANATE NEODYME, PROCESSES FOR THEIR PREPARATION AND THEIR APPLICATIONS IN CERAMIC COMPOSITIONS |
| JPS63259927A (en) * | 1987-04-17 | 1988-10-27 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of thin film of superconductive matter |
| NL8701787A (en) * | 1987-07-29 | 1989-02-16 | Philips Nv | METHOD FOR MANUFACTURING OXIDICALLY SUPER CONDUCTIVE MATERIAL |
-
1990
- 1990-02-20 WO PCT/US1990/000809 patent/WO1990009961A1/en not_active Application Discontinuation
- 1990-02-20 JP JP2504037A patent/JPH04503657A/en active Pending
- 1990-02-20 AU AU51677/90A patent/AU5167790A/en not_active Abandoned
- 1990-02-20 KR KR1019910700904A patent/KR920701046A/en not_active Application Discontinuation
- 1990-02-21 CA CA002010615A patent/CA2010615A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990009961A1 (en) | 1990-09-07 |
| JPH04503657A (en) | 1992-07-02 |
| CA2010615A1 (en) | 1990-08-23 |
| KR920701046A (en) | 1992-08-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4861753A (en) | Process for making superconductors using barium nitrate | |
| AU633509B2 (en) | Superconducting metal oxide compositions | |
| US5591698A (en) | Low temperature (T lower than 950° C.) preparation of melt texture YBCO superconductors | |
| US6855670B1 (en) | Superconducting bismuth-strontium-calcium-copper oxide compositions and process for manufacture | |
| AU5167790A (en) | Process for making superconducting metal oxide compositions | |
| US5079217A (en) | Process for preparing homogenous superconductors by heating in a nitrogen dioxide containing atmosphere | |
| EP0366721A4 (en) | Improved process for making 90 k superconductors | |
| Majewski et al. | Precipitation and pinning in Ca and Sr-Rich High-T c superconducting “Bi 2 Sr 2 CaCu 2 O 8” ceramics | |
| HU217018B (en) | Super conducting composition contain bismuth, strontium, copper and oxygen, process for producing this composition, and process for conducting an electrical current within a conductor material without electrical resistive losses and josephson-effect ... | |
| JPH06263441A (en) | Metal oxide material and its production | |
| AU632076B2 (en) | Superconducting metal oxide compositions and processes for manufacture and use | |
| Lee et al. | (Pb, Ti), a new superconductor in the Pb-1212 family | |
| EP0445138B1 (en) | Process for preparing homogeneous high temperature superconductors | |
| EP0428630B1 (en) | Superconducting metal oxide compositions and processes for manufacture and use | |
| WO1988009555A1 (en) | Improved process for making 90 k superconductors | |
| Song et al. | Low-temperature (T⩽ 950° C) preparation of melt-textured YBa2Cu3O7− δ superconductors | |
| EP0441903A4 (en) | Superconducting metal oxide compositions and processes for manufacture and use | |
| WO1989007086A1 (en) | SUPERCONDUCTING Bi-Sr-Ca-Cu OXIDE COMPOSITIONS AND PROCESS FOR MANUFACTURE | |
| Moon et al. | Recrystallization of 110 K high-Tc Bi2Sr2Ca2Cu3Ox superconducting phase from the molten state and characterizations | |
| Mohan et al. | Preparation and superconductivity properties of Ba2DyCu3O7 | |
| JPH09502959A (en) | Superconductor containing at least one of barium and strontium and thallium, copper, oxygen and fluorine | |
| Rukang et al. | THE STRUCTURE AND SUPERCONDUCTIVITY OF A NEW SERIES OF LAYERED CUPRATES MSr2 (LAR) 2Cu2010-8 (M= Ta, Nb) | |
| WO1991011391A1 (en) | Superconducting metal oxyde compositions |