WO1989008076A1 - SUPRACONDUCTIVITE DANS UN SYSTEME DE COMPOSES D'OXYDES Bi-Ca-Sr-Cu EXEMPT DE TERRES RARES - Google Patents

SUPRACONDUCTIVITE DANS UN SYSTEME DE COMPOSES D'OXYDES Bi-Ca-Sr-Cu EXEMPT DE TERRES RARES Download PDF

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WO1989008076A1
WO1989008076A1 PCT/US1989/000685 US8900685W WO8908076A1 WO 1989008076 A1 WO1989008076 A1 WO 1989008076A1 US 8900685 W US8900685 W US 8900685W WO 8908076 A1 WO8908076 A1 WO 8908076A1
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temperature
composition
bcsco
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oxide
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Ching-Wu Chu
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University Of Houston-University Park
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    • C04B35/4521—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 bismuth oxide
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    • H10N60/00—Superconducting devices
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    • H10N60/00—Superconducting devices
    • H10N60/80—Constructional details
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    • H10N60/855—Ceramic superconductors
    • H10N60/857—Ceramic superconductors comprising copper oxide
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Definitions

  • This invention relates to superconducting compositions, i.e., compositions offering no electrical resistance at a temperature below a critical temperature; to processes for their production and to methods for their use. Superconductivity was discovered in 1911.
  • the first observed and most distinctive property of a superconductive material is the near total loss of electrical resistance by the material when at or below a critical temperature that is a characteristic of the material.
  • This critical temperature is referred to as the superconducting transition temperature of the material, T .
  • T the superconducting transition temperature of the material
  • NbN was observed with a transition temperature of about 14° K
  • Nb 3 Sn was reported in the early 1950 ! s
  • Nb 3 (Al-Ge) was reported in the late 1960's
  • Nb 3 Ge was reported in the early 1970"s to have a transition temperature of up to 21° K.
  • Careful optimization of Nb 3 Ge thin films led to an increase of the critical temperature for such material up to 23.3° K. While this work led to progress the maximum temperature at which superconductivity could occur was raised to only 23.3° K since research started three-quarters of a century ago.
  • the existing theories explained the superconductivity of these materials, but did not predict superconductivity of higher than 40° K. Significant progress in finding materials which superconduct at higher transition temperatures than that of Nb 3 Ge thin films was not made until 1986.
  • Superconductivity is a potentially very useful phenomenon. It reduces heat losses to zero in electrical power transmission, magnets, levitated monorail trains and many other modern devices. However, superconductivity of a material occurs only at very low temperatures. Originally, and until the inventions outlined herein, liquid helium was the required coolant to provide the conditions necessary for superconductivity to occur.
  • My copending application Serial No. 012,205 entitled “High Transition Temperature Superconducting Composition” discloses a mixed phase oxide prepared according to a nominal formulation of Yj ⁇ Ba.osCuO ("y" is a number from greater.
  • My copending application Serial No. 012,205 entitled “High Transition Temperature Superconducting Composition” discloses a mixed phase oxide prepared according to a nominal formulation of Yj ⁇ Ba.osCuO ("y” is a number from greater.
  • composition of the general formula LM 2 A 3 0 6+9 may be prepared wherein "L” is scandium, yttrium, a rare earth element (atomic numbers 51 to 71) or mixtures thereof; “M” is barium, strontium, calcium, magnesium, mercury or mixtures thereof; “A” is copper, bismuth, titanium, tungsten, zirconium, tantalum, niobium, vanadium or mixtures thereof; and “M” is preferably barium or strontium and "A” is preferably copper.
  • a superconducting composition comprising a metal oxide of the formula wherein.
  • T is a trivalent transition metal such as Bi, Tl, In, Sb, or mixtures thereof;
  • M* is a mixture of alkaline earth metals such as Sr and Ca, Sr and Mg, and Ca and Mg in ratio of the alkaline earth metal of larger atomic radius (M ) to the alkaline earth metal of smaller atomic radius (M s ) of from about 1:1 to about 3:1;
  • “d” is a number from about 1 to about 3;
  • e is a number from about 1 to about 6;
  • f is a number from about 1 to about 6;
  • G is a number between from about (3d + 2e + 2f)/2 to about (3d + 2e + 3f)/2 that provides the metal oxide with zero electrical resistance at a temperature of 77°K or higher.
  • T is bismuth;
  • M* is Ca and Sr at a ratio of 1:2;
  • d is 2;
  • the trivalent element "T” and the selection of an alkaline earth metal pair in appropriate ratio in view of their atomic radius to correspond the alkaline earth metal pair to the atomic radius size of the trivalent element "T” employed, is crucial to obtaining a metal oxide composition that will crystallize to a form favorable to high temperature superconduction.
  • a crystalline form in which Cu-atoms are in planar configuration is required for high T .
  • the crystalline form that provides for high T is a perovskite related structure with substantial deviations from the ideal perovskite arrangement of metal atoms. Hence in the high
  • Tc species of Bi 2 Ca ! Sr 2 Cu 2 0g (g 8 to 9) bismuth appears to be concentrated in layers similar to the Bi 2 0 2 slabs of phases such as BaBi 4 Ti 4 0 15 discussed by B. Aurivilius, Arkiv Kemi 1, 499 (1950).
  • the weak electron density associated with every fourth layer of the crystalline structure suggests interlayers region of weak bonding.
  • copper-oxygen layers appear to be continuous over hundreds of unit cells.
  • Fig. 1 illustrates DTA, TGA, and DTG results for BCSCO-a and -b in air with compositions Bi:Ca:Sr:Cu being 1:1:1:1 and 1:1:1:2.
  • the scan speed for temperature is 20°/min.
  • T M is the meling point.
  • Fig. 2 illustrates the temperature dependence of resistance for Bi-Ca-Sr-Cu oxide superconductor compositions prepared of nominal formula 1:1:1:1 (BCSCO-a); 1:1:1:2 (BCSCO-b); and 1:1:1:3 (BCSCO-c).
  • Fig. 3 illustrates the temperature dependence of magnetization for the Bi-Ca-Sr-Cu oxide superconductor species BCSCO-a and BCSCO-c.
  • Fig. 4 illustrates selected-area electron diffraction pattern of the Bi-Ca-Sr-Cu oxide superconductor showing hkO diffraction spots. Strong spots correspond to o 2.7 x 2.7 A subcell, while superlattice reflections along o a * and b * indicate spacings of 5.4 and 27.2 A respectivel .
  • Fig. 5 illustrates selected-area electron diffraction pattern of the 002. diffraction row, which is streaked but o shows a strong 15.4 A periodicity. The 004 difraction is indicated. Also illustrated is a high-resolution image o taken parallel to the layers shows the 15.4 A spacing, o with subspacings of 3.8 A. The contrast of these layers differs, suggesting a possible ABAC-ABAC type stacking of perovskite units. A structural defect (arrowed) may correspond to a Bi-free region of Ca-Sr-Cu perovskite.
  • Fig. 6 illustrates the selected-area Ok£ electron diffraction pattern as characterized by an A-centered o
  • FIG. 7 illustrates X-ray results for BCSCO-b synthesized at different temperatures: a - 820°C, b - 864°C, c - 880°C, d - the superconducting phase.
  • Curve e is for BCSCO-c with composition ratio of 1:22:14:6.2 synthesized at 850°C.
  • Fig. 8 illustrates resistance (R) vs. temperature (T) for BCSCO-b synthesized at different temperatures; a - 820°C, b - 864°C, c - 880°C.
  • Curve d is for BCSCO-c.
  • Fig. 9 illustrates magnetization (M) vs. T for BCSCO-b synthesized at different temperatures: a - 820°C, b - 864°C, c - 880°C. Curve d is for BCSCO-c.
  • Fig. 10 illustrates R - T for BCSCO-b in different magnetic fields.
  • Another species of materials within the formula [L ⁇ _ M ] A, O has been found which has zero electrical resistance at a temperature of 77°K or higher.
  • the species comprises that class of compositions wherein "x" equals 1, to yield a formula of M* a A* b O y wherein the M* constituent comprises a mixture of divalent alkaline earth metals and the A* constituent comprises a mixture of copper with at least one other "A", preferably bismuth.
  • the M* constituent is a 1:1 mixture of Ca and Sr
  • the A* constituent is a 1:1 mixture of Cu and Bi
  • "a" is 1. Accordingly, an oxide material prepared to a nominal formula of (Ca 0 . 5 Sr 0 . 5 ) 1 (Cu 0 .sBi 0 • 5 ) ⁇ O yields a multiphase material which exhibits zero electrical resistance at a temperature of 77°K or higher. The material does not contain a rare earth metal.
  • the 1:1:1:3 nominal composition is analogous to the LM 2 Cu 3 0 6+9 class of high temperature superconductor materials disclosed in my copending application Serial Nos. 12,205 and 32,041.
  • the nominal composition of that phase determined to be the phase responsible for the high temperature superconduction has been determined to be as follows:
  • Trivalent metals ("T") other than bismuth may be employed in the production of a high temperature superconductive oxide material of the formula M * a A *b° v - Desirably such other trivalent metals should have an o atomic radius no smaller than 1.5 A and no larger than 2.1 A.
  • the trivalent element "T” and the selection of an alkaline earth metal pair in appropriate ratio in view of their atomic radius to correspond the alkaline earth metal pair to the atomic radius size of the trivalent element "T” employed, is crucial to obtaining a metal oxide composition in which a phase will crystallize to a form favorable to high temperature superconduction. A crystalline form in which Cu-atoms are in planar configuration is required for high T .
  • the crystalline form that provides for high T is a perovskite related structure with substantial deviations from the ideal perovskite arrangement of metal atoms.
  • bismuth appears to be concentrated in layers similar to the Bi 2 0 2 slabs of phases such as BaBi 4 Ti 4 0 15 discussed by B. Aurivilius, Arkiv Kemi 1, 499 (1950).
  • High resolution transmission electron microscopy (TEM) images show that the compound has a four-layer structure and that the bonding between every fourth layer is weak.
  • copper-oxygen layers appear to be continuous over hundreds of unit cells.
  • Bi:Ca:Sr:Cu of 1:1:1:1; 1:1:1:2; or 1:1:1:3 may be represented as a metal oxide of the formula
  • transition metal such as Bi
  • M* is a mixture of alkaline earth metals such as Sr and Ca, Ba and Sr, Ba and Ca, Sr and Mg, and Ca and Mg in a ratio of the alkaline earth metal of larger atomic radius (M ) to the alkaline earth metal of smaller atomic radius (M s ) of from about 1:1 to about 1:3;
  • "d" is a number from about 1 to about 3;
  • "e” is a number from about 1 to about 6;
  • f is a number from about 1 to about 6;
  • G is a number between from about (3d + 2e + 2f)/2 to about (3d + 2e + 3f)/2 that provides the metal oxide with zero electrical resistance at a temperature of 77°K or higher.
  • T is bismuth;
  • M* is Ca and Sr at ratio of 1:2;
  • "d” is 2;
  • "e” is 3;
  • a method for making such ⁇ o ' M * e Cu f0 ⁇ containing superconductive composition oxide materials includes the following steps, and for convenience is referred to as the compressed powder reaction method.
  • Selected amounts of solid powdered compounds containing T, M , M , A, and O are thoroughly mixed preferably by selecting appropriate amounts of T 2 0 3 , M C0 3 , M s C0 3 (or M O and M S 0)and AO.
  • the thoroughly mixed powder mixture is compressed into pellets which are thereafter reacted at a temperature between about 800°C and about 910°C, preferably about 850°C to about 890°C, for a time sufficient to complete the solid state reaction. Thereafter the reacted pellets are rapidly quenched to room temperature.
  • Pelletization of the oxide mixture is carried out at an applied pressure of from about 100 to about 30,000 psi and preferably at an applied pressure of from about 100 to about 500 psi, most preferably at about 500 psi.
  • Reaction of the pelletized mixture may be conducted in air for about 5 minutes to about 24 hours, and most preferably in a reduced oxygen atmosphere of about 2000 ⁇ for about 5 to about 30 minutes preferably for about 5 to about 15 minutes. Following the completion of the reaction step the reacted pellet composition is rapidly quenched to room temperature in air.
  • Sample preparation parameters can affect the electronic and magnetic properties of the ⁇ d M * e Cu f° ⁇ class of oxide compounds drastically. It has been observed that the formation conditions for Td,M*eCuf. e C)g for different "T's" are different.
  • the reaction time, the reaction temperature, the quenching rate, the reaction atmosphere and the compositions are all inter-related. For instance, oxide complexes within this class can be made insulating, partially superconducting or completely superconducting by varying the reaction temperature and the quenching rate while keeping the compositions unchanged.
  • the reaction temperature can be reduced by increasing the "d” parameter, reducing the "f” parameter, increasing the "T” component with greater atomic radius or doping the composition with monovalent alkaline elements.
  • the reaction atmosphere is a reduced oxygen atmosphere of about 2000 ⁇
  • the reaction may be conducted at a lower temperature than where the reaction is carried out under atmospheric conditions.
  • the reaction temperature required to produce an oxide complex having superconducting properties is from about 800 to about 950°C and preferably from about 820 to about 910°C.
  • the temperature required to produce superconducting properties is from about 800°C to about 910°C preferably from about 850°C to about 890°C.
  • reaction atmosphere For either type of reaction atmosphere higher temperatures, up to the melting point of the lowest melting component of the starting materials in eutectic admixture, could be employed; however it is sometimes preferred to use such higher reaction temperatures since they may tend to promote the formation of the oxide complex compared to that optimum attainable by use of lower reaction temperatures.
  • the optimum reaction temperature is dependent upon the elemental composition of the oxide complex being prepared and the optimum reaction temperature for a particular oxide complex may be established without undue experimentation. Reactions carried out at temperatures significantly lower than as discussed above generally result in an oxide complex that has only insulating or semiconducting electrical properties rather than superconducting properties.
  • reaction atmosphere employed also influences the time of reaction to completion.
  • reaction under a reduced oxygen atmosphere of about 2000 ⁇ requires a significantly shorter reaction, on the order of about 3 to 45 minutes for gram size reactions, compared to an atmospheric reaction, which generally requires from about 5 minutes to 8 hours for gram size reactions.
  • a similar trend would be expected for larger scale reactions, although the optimum reaction time for such larger scale reaction would have to be determined by observation.
  • One method for determination of the completion of reaction is to monitor samples by X-ray diffraction for depletion of diffraction peaks that correspond to the starting material and growth to maximum intensity of diffraction peaks which correspond to the desired T (j M *e Cu f 0 a phase.
  • the optimum reaction time is dependant upon the elemental composition of the oxide complex being prepared and the reaction temperature and may be established by observation without undue experimentation. Optimum superconducting properties are obtained by timing the reaction to that point wherein the maximum amount of starting materials have been converted to the desired Td,M*eCufJDg p F hase.
  • Td,M*eCufJDg p F the reaction temperature
  • the superconducting compositions of the present invention have the potential for being used in a wide variety of applications.
  • they when used in a wire or conductor form, they may be used in electrical power transmission, energy storage, controlled fusion reaction, electricity generation, mass transportation and magnets.
  • they In a thin film form, they may be used in ultra-sensitive detectors and in ultra-fast computers.
  • they may be used in a superconducting-magnetic-superconducting multi-layer form for use in ultra-sensitive ultra-fast electromagnetic micro devices.
  • Bi-Ca-Sr-Cu-oxide systems is representative of the ⁇ o ' M * e Cu f 0 Cf oxide complexes and methods of producing the oxide complexes of the invention.
  • the standard 4-probe technique was used to measure resistivity, and an inductance bridge was employed for ac magnetic susceptibility ⁇ -determination and a magentometer was used for dc magnetization measurements.
  • the temperature was measured using the Au+0.07%Fe-chromel, and chromel-alumel thermocouples in the absence of a magnetic field, and a carbon-glass thermometer in the presence of a field. The latter was calibrated against the former without a field. Magnetic fields up to 6T were generated by a superconducting magnet.
  • BCSCO samples Three Bi-Ca-Sr-Cu-O (hereafter BCSCO) samples were synthesized by the described solid-state reaction techniques from appropriate amounts of Bi 2 0 3 , CuO, SrC0 3 , and CaC0 3 .
  • the BCSCO samples were prepared according to a nominal composition of 1:1:1:1 for BCSCO-a; 1:1:1:2 for BCSCO-b, and 1:1:1:3 for BCSCO-c.
  • the starting ingredients used were Bi 2 0 3 , (99-99.999%), Bi(N0 3 ) 3 .5H 2 0 (99.99%), CaC0 3 (99-99.995%), SrC0 3 (99-99.999%) and CuO (99-99.999%).
  • the initial powder materials of appropriate amounts were thoroughly mixed.
  • the only partial Meissner effect may be attributed to the multiphase nature and/or low flux trapping of the BCSCO sample. Greater Meissner effects (up to 60%) have been detected in other BCSCO samples; in some specimens as much as two-thirds of the effect is associated with the 115K transition.
  • X-ray powder diffraction patterns of the Cu-rich BCSCO-c sample revealed a substantial amount of unreacted copper oxide, which was not present in BCSCO-a or -b. Samples were examined by optical and electron microscopy, x-ray powder and single-crystal diffraction, and electron microanalysis. Powder x-ray diffration patterns were made on a Rigaku DMAX-3B automated diffractometer.
  • the BCSCO samples comprised at least four phases, two phases were alkaline earth copper oxides, another phase was a bismuth alkaline earth oxide, and the four phase was the superconductor phase.
  • Elongated subhedral to euhedral crystals of a tranparent, birefringent, pleochroic (red to colorless) phase was prominent in grain mounts of all three of the BCSCO (a,b, and c) samples examined with a polarizing microscope. Needle-like crystals up to 100 ⁇ m long, though abundant in some samples, constitute a small fraction (probably less than 5%) of the sample volume. Electron microanalysis of five different crystals of this insulating phase yields an average composition of (Ca Sr )2(Cu Bi )0 3 .
  • O *92 0-08 0*96 0*3 may represent background secondary scattering from adjacent Bi-rich phases; therefore, this crystalline phase may be bismuth free.
  • a second bismuth-poor phase distinguished in grain mounts as black, opaque, elongated euhedral to subhedral grains up to 60 ⁇ m long, was found in samples BCSCO-b and BCSCO-c to have a composition of approximately (Ca 0 . 6 Sr 0 . 4 )Cu t . 75 0 3 based on microanalysis of four grains. Approximately 0.03 atoms of bismuth were also detected per one alkaline earth cation. Three crystals of this phase were examined by single-crystal x-ray techniques. Though the stoichiometry is similar to CaCu 2 0 3 , the unit cell and structure differ from those reported by Teske and Mtlller-Buschbaum, Z Anorg. Alle.
  • the fourth phase which is the superconducting compound, was abundant in all three samples. It was distinguished by a layered structure probably related to the class of layered bismuth compounds described by Aurivillus Arkiv. Kemi, 1, 463 and 499 (1950). These structures incorporate both perovskite-type layers and unusual Bi 2 0 2 layers of bismuth in distorted four coordination. Transmission electron microscopy (TEM) revealed that the grains possessed a perfect basal (hereafter termed 001) cleavage, similar to that of clay minerals. The structure, therefore, must consist of a layered atomic arrangement with planes of weak bonding.
  • TEM Transmission electron microscopy
  • Electron diffraction in the TEM of the (001) layers is facilitated by the tendency of almost every grain to lie flat on the holey carbon film.
  • Numerous (hkO) electron diffraction patterns were obtained (Figure 4), all of o which show a prominent perovskite-like 2.7 x 2.7 A subcell o and a distinctive 5.41 x 27.2 A supercell.
  • a few grains, lying near the edge of the grid, were found to be oriented with (001) layers perpendicular to the grid. From these o crystallites a stacking periodicity of 15.39 A was observed (Figure 5).
  • High-resolution images of these gorains clearly revealed a four-layer structure with a 3.86
  • the superconductor phase occurs in fine-grained masses of black, opague flattened crystallites.
  • the average diameter of these thin plates is less than 5 ⁇ m and the thickness is usually less than 0.1 ⁇ m.
  • Polished scanning electron microscopy (SEM) mounts revealed that this phase forms a matrix of randomly-oriented interlocking flakes in which the other single-crystal phases "float.” This texture implies that the superconducting phase crystallized last, at a lower temperature than the other phases.
  • the average composition of the superconductor was determined from 15 analyses from three different samples. The ratio of cations approximates 2:1:2:2 for Bi:Ca:Sr:Cu. The average formula may be represented more precisely as Bi 2 (Sr Ca " Bi ) Cu 2 0 8 . ⁇ s . Note that bismuth can
  • the new structure high temperature superconductor Bi 2 CaSr 2 Cu 2 0 (g is 8 to 9) is closely related to the 22 K y superconducting phase described by Michel et al, Z_ ⁇ Phys. ,
  • a one-dimensional electron density profile is calculated based on the observed powder diffraction intensities of 001 reflections. This analysis indicates a pronounced layering of cations in (001), with substantial deviations from the ideal perovskite arrangement of metal atoms. Bismuth appears to be concentrated in layers, perhaps similar to the Bi 2 0 2 slabs of phases such as BaBi 4 Ti 4 0 15 . Weak electron density associated with every fourth layer of the structure suggests interlayer regions of weak bonding. It may be speculated that copper and oxygen adopt the planar configuration common to the other known high-temperature oxide superconductors, but there is not yet any direct evidence to support this supposition. Superstructures parallel to the a and b axes may be the result of cation and oxygen ordering.
  • the copper-oxygen layers appear to be continuous over hundreds of unit cells.
  • This layered structure may possess one significant advantage in terms of processing and applications. Fabrication of the superconductor by compression into planes yield superconductor components with enhanced properties (e.g., critical current) in a specific plane. Similarly, fabrication by rolling could produce wires more flexible than those of ordinary ceramic materials.
  • Table II gives the data obtained by a powder x-ray analysis of the superconducting Bi-Ca-Sr-Cu oxide phase. Patterns were obtained with filtered Cu radiation. Pure silicon (NBS Standard References material 640) was used as an internal standard.
  • Figure 4 illustrates selected-area electron diffraction pattern of the Bi-Ca-Sr-Cu oxide superconductor showing hkO diffraction spots. Strong o spots correspond to 2.7 x 2.7A subcell, while superlattice reflections along a and b indicate spacings of 5.4 and o
  • Figure 5 illustrates selected-area electron diffraction pattern of the 00£ diffraction row, which is o streaked but shows a strong 15.4 A periodicity. The 004 diffraction is indicated.
  • Figure 5 also illustrates a high-resolution image o taken parallel to the layers shows the 15.4 A(001) o spacing, with subspacings of 3.8 A. The contrast of these layers differs, suggesting a possible ABAC-ABAC type stacking of perovskite units.
  • a structural defect
  • Figure 6 illustrates the selected-area Ok£ electron diffraction pattern is characterized by an A-centered 27 x o 31 A lattice.
  • Figure 6 also illustrates a high-resolution image of the (100) plane reveals numerous stacking faults and defects as well as the A-centered layered structure.
  • locally inclined blocks may indicate a fine-scale twinning or may represent "monoclinic" regions of related but different structure.
  • BCSCO is a quinary superconducting compound system, consisting of the trivalent Bi. Structural data shows that the 9OK-transition in BCSCO is associated with the
  • Typical resistance (R) and magnetization (M) results are shown respectively in Figs. 8 and 9 for BCSCO-b, synthesized at different temperatures. It is clear that both the T and the Meissner effect grow as the synthesis temperature increases. The 120K transition occurs only when the sample is synthesized above ⁇ 850K, although lower T happens in samples prepared at lower temperatures.
  • the magnetic field effect of R for a BCSCO-b sample is shown in Fig. 10.
  • the transition is clearly suppressed to lower temperature and broadened in the presence of magnetic field.
  • the broadening is similar to that observed in LBa 2 Cu 3 0 6+9 polycrystalline compounds due to the weak coupling between the highly anisotropic structure of the compounds.
  • the upper critical field at 0°K for the 120K transition is estimated to be ⁇ 187T.
  • the structure study showes that the BCSCO material with compositions 2:1:2:2 superconduct at ⁇ 90K have a four-layer structure, although the exact atomic arrangement is yet to be determined. Numerous structural defects have been observed in microcrystalites of this compound and have been suggested to be responsible for the existence of a large homogeneity range in BCSCO.
  • the high T phase i.e. ⁇ 120K, may have a homologous structure closely related to the 2:1:2:2 phase. This is consistent with the observation of similar X-ray diffraction patterns of samples with T ranging from 40 to 120K. Single crystals with a T ⁇ 90K have been obtained and investigated.
  • the T of BCSCO compositions depends sensitively on the synthesis temperature but not on the Cu to Bi ratio. High T phase appears only for samples prepared at temperatures above 850°C but below melting. The present study also demonstrates that there exists a large homogeneity range for the superconducting phase to form, preferably in a Cu-rich environment. This raises questions concerning the essential role of planar configuration of Cu-ions in BCSCO.
  • the 12OK-transition phase may possess a homologous structure of the newly identified 2:1:2:2 90K phase. Even higher T may be achievable in this system with increasing complexity in crystal chemistry.

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Abstract

On a mis au point une composition supraconductrice comprenant un oxyde métallique de la formule TdM*eCufOg dans laquelle ''T'' est un métal de transition trivalent tel que Bi, Tl, In, Sb ou des mélanges de ceux-ci; ''M*'' est un mélange de métaux alcalino-terreux tels que Sr et Ca, Sr et Mg, et Ca et Mg dans un rapport de métal alcalino-terreux de rayon atomique supérieur (ML) et de métal alcalino-terreux de rayon atomique inférieur (Ms), d'environ 1:1 à environ 3:1; ''d'' représente un nombre compris entre environ 1 et 3; ''e'' représente un nombre compris entre environ 1 et 6' ''f'' représente un nombre compris entre 1 et 6; ''g'' représente un nombre compris entre environ (3d + 2e + 2f)/2 et (3d + 2e + 3f)/2, produisant l'oxyde métallique avec une résistance électrique zéro à une température de 77°K ou plus. De préférence ''T'' représente du bismuth; ''M*'' représente Ca et Sr dans un rapport de 1:2; ''d'' représente 2; ''e'' représente 3; ''f'' représente 2 et ''g'' représente un nombre compris entre environ 8 et 9 ce qui confère à ladite composition une résistance électrique zéro à une température de 77°K ou plus.
PCT/US1989/000685 1988-03-03 1989-02-21 SUPRACONDUCTIVITE DANS UN SYSTEME DE COMPOSES D'OXYDES Bi-Ca-Sr-Cu EXEMPT DE TERRES RARES WO1989008076A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0347770A2 (fr) * 1988-06-20 1989-12-27 Daikin Industries, Limited Fabrication d'un oxyde supraconducteur de la famille du bismuth
AU608946B2 (en) * 1988-02-05 1991-04-18 Hoechst Aktiengesellschaft Superconductor and process for its preparation
ES2226577A1 (es) * 2003-09-12 2005-03-16 Universidad Complutense De Madrid Nuevos electrolitos solidos basados en oxido de antimonio.

Non-Patent Citations (7)

* Cited by examiner, † Cited by third party
Title
CHEM. & ENG. NEWS, Vol. 66, No. 5, published 01 February 1988, R. DAGANI, "New class of superconductors discovered", See page 5, note mention of 1-22-88 annoucement by MAEDA et al. *
DUPONT CORPORATE NEWS, press release dated 09 February 1988, See both pages. *
JPN. J. APPL. PHYS., Vol. 26, No. 12, published December 1987, J. AKIMITSU et al., "Superconductivity in the Bi-Sr-Cu-O System", see pages L2080-L2081. *
JPN. J. APPL. PHYS., Vol. 27, No. 2, published February 1988, H. MAEDA et al., "A New... without a Rare Earth Element", see pages L209-L210. *
PHYS. REV. B., Vol. 38, No. 1, published 01 July 1988, S.A. SUNSHINE et al., "Structure...Bi2.2Sr2Ca0.8Cu208+d", see pages 893-896 and note 12 February 1988 submission date. *
SCIENCE, Vol. 239, published 26 February 1988, M.A. SUBRAMANIAN et al., "A New High-Temperature Superconductor: Bi2Sr3-xCaxCu208+Y", note submission date of 09 February 1988 and see pages 1015-1017. *
SUPERCONDUCTOR WEEK, Vol. 2, No. 6, published 08 February 1988, "Chu Team Reports Further Advances Using Bismuth Materials", see page 1 and note reference to Japanese work. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU608946B2 (en) * 1988-02-05 1991-04-18 Hoechst Aktiengesellschaft Superconductor and process for its preparation
EP0347770A2 (fr) * 1988-06-20 1989-12-27 Daikin Industries, Limited Fabrication d'un oxyde supraconducteur de la famille du bismuth
EP0347770B1 (fr) * 1988-06-20 1996-03-27 Daikin Industries, Limited Fabrication d'un oxyde supraconducteur de la famille du bismuth
ES2226577A1 (es) * 2003-09-12 2005-03-16 Universidad Complutense De Madrid Nuevos electrolitos solidos basados en oxido de antimonio.

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