Source: https://patents.google.com/patent/CA1307916C/en
Timestamp: 2019-02-16 08:37:33
Document Index: 269696276

Matched Legal Cases: ['in fine', 'art 15', 'art 15', 'art 15', 'art 1', 'art 25', 'art 25', 'art 25']

CA1307916C - Method of forming superconducting circuit - Google Patents
CA1307916C
CA1307916C CA000562820A CA562820A CA1307916C CA 1307916 C CA1307916 C CA 1307916C CA 000562820 A CA000562820 A CA 000562820A CA 562820 A CA562820 A CA 562820A CA 1307916 C CA1307916 C CA 1307916C
CA000562820A
1987-03-30 Priority to JP7936187 priority Critical
1987-03-30 Priority to JP79361/1987 priority
1987-04-14 Priority to JP91123/1987 priority
1987-04-14 Priority to JP9112387 priority
1987-08-22 Priority to JP20888187 priority
1987-08-22 Priority to JP208881/1987 priority
1988-03-29 Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
1992-09-29 Publication of CA1307916C publication Critical patent/CA1307916C/en
A method of forming a superconducting circuit comprises the steps of preparing a ceramics body which is changed from a non-superconductive phase not superconducting at the working temperature into a superconducting phase superconducting at the working temperature by heat treatment and performing the heat treatment on a part of the ceramics body by applying a laser beam to the ceramics body to change the same into the superconductive phase, thereby to form a superconducting circuit consisting of the superconductive phase and the non-superconductive phase on the ceramics body.
TITL~ OF THE INVENTION
~ethod of Forming Superconducting Circuit BACKGR~UND OF THE INVEMTION
Field of the Invention The present invention relates to a method of forming a superconducting circuit, and more particularly, it relates to a method of formin~ a superconducting circuit on a superconductive ceramics material.
Description of the Related Art A superconductive ceramics material is prepared by mixing raw powder materials of oxides, compression-molding the mixture into a prescribed configuration of a block, a sheet or the like and sintering the same, for example.
However, it has been difficult to form a fine superconducting circuit by such a method of utilizing compression molding.
In another conventional method of forming a superconducting circuit, a substrate is masked to form a superconducting thin film only on a prescribed portion, ~0 thereby to implement a circuit. Alternatively, ion sputtering is performed on a superconducting thin film formed on a substrate to partially scrape off the thin film, thereby to form a circuit.
'3~$
- However, such conventional methods have disadvantages of difficulty in fine worXing, inferior working accuracy and complicated steps.
In the inventive method of forming a superconducting circuit, a ceramics body, which is changed from a non-superconductive phase not superconducting at its working temperature into a superconductive phase superconducting at the working temperature by heat treatment, is prepared and a laser beam is applied to the ceramics body to perform the said heat treatment on a part of the ceramics body for changing the same into the superconductive phase, thereby to form a superconducting circuit consisting of the superconductive phase and the non-superconductive phase on the cer~mics body.
- The present invention is based on such an empirically known phenomenon that superconductivity is effectuated or a critical temperature of superconduction is increased by per~orming heat treatment in the process of manufacturing a superconducting ceramics material.
When a laser beam is applied onto a part of a ceramics body which is changed from a non-superconductive '`
1 307q 1 6 phase into a superconductive phase by heat treatment, only the part exposed to the laser beam is heated ta enter a superconductive phase while the rest remains in a non-superconductive phase. Thus, fine working can be performed in correspondence to the diameter of the laser beam by applying the laser be m to only a part to be provided with a superconductive phase and scanning the same, thereby to form a superconducting circuit.
Raw materials for the ceramics body may be arbitrarily prepared so far as the same contain elements which can form a superconducting substance. Preferably such raw materials are prepared by at least a single sort of element selected fxom those belonging to the groups Ia, IIa and IIIa of the periodic table, at least a single sort of element selected from those be~onging to the groups Ib, IIb and IIIb of the periodic table and at least a single sort of element selected from oxygen, fluorine, sulfur, carbon and nitrogen.
The elements belonging to the group Ia of the periodic table are H, Li, Na, K, Rb, Cs and Fr. The elements belonging to the group lIa of the periodic table are Be, Mg, Ca, Sr, Ba and Ra. The elements belonging to the group IIla of the periodic table are Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr.
1 3[)791 6 The elements belonging to the group Ib o~ the periodic table are Cu, Ag and Au. I'he elements belonging to the group IIb of the periodic table are Zn, Cd and Hg.
The elements belonging to the group IIIb of the periodic table are B, Al, Ga, In and T:L.
The raw materials are pre~erably prepared by at least a single sort of element selected from those belonging to the group Ib of the periodic table, at least a single sort of element selected from those belonging to the group IIa, at least a single sort of element selected from those belonging to the group IIIa and oxygen.
Cu and Ag, particularly Cu is preferable in the elements belonging to the group Ib of the periodic table and Sr, Ba and Ca are preferable in the elements belonging to the group Ila, while Sc, Y and La are preferable within the elements belonging to the group Illa.
At least one or two sorts of raw materials containing the aforementioned elements are employed in the form of powder, for example. Such powder is prepared by a compound such as an oxide, a carbo-oxide, a fluoride, a sulfide, a carbide or a nitride containing the aforementioned elements. Within such compounds, an oxide or a carbo-oxide, particularly an oxide containing oxygen is preferable. Further, the raw materials pre~erably contain at least copper oxide (CuO), in order to obtain a 1 307q 1 6 superconductive ceramics material having a high critical temperature.
A ceramics material being in composition expressed in the ~ollowing general formula 11) is preferable because o~
a relatively high critical temperature:
AaBbCc .. (1) where A represents at least a single sort of element selected ~rom those belonging to the groups Ia, lIa and IIIa of the periodic table, B represents at least a single sort of element selected ~rom those belonging to the groups Ib, Ilb and IIIb of the periodic table and C
represents at least a single sort of element selected from oxygen, fluorine, nitrogen, carbon and sulfur.
~ A laser employed in the present invention is : preferably prepared by that of high output, in order to improve efficiency of heat treatme~t. Examples of the laser are solid-state lasers such as a ruby laser, a glass laser an~ a YAG laser o~ 1.06 ~m in wavelength, gas lasers such as an He-Ne laser, a Kr laser, an Ar laser, an excimer laser and a CO2 laser o~ 10.6 ~m in wavelength, a semiconductor laser and the like. Within these, the CO2 laser and the YAG laser are paxticularly preferable. The laser beam is pre~erably converged through a lens to be 1 307ql 6 applied onto a ceramics body, in order to increase heating efficiency. A point of application of the laser beam is preferably moved while applying the same in a ~ocused state to the surface of the ceramics body. Alternatively, a spot of prescribed size may be formed on the surface of a substrate in a defocused state for locally heating the same, in response to width of an interconnection part of a desired superconducting circuit.
The film thus formed on the substrate by sputtering or the like is not directly superconductive, or the same superconducts only at a temperature lower than its worXing temp~rature. The film may superconduct at the working temperature only when the same is subjected to heat treatment. The ceramics body employed in the present invention is in the state of such a film hefore heat - treatment. A laser beam is applied to such a film to perform heat treatment, thereby to form a superconducting circuit having a superconductive phase only in a part exposed to the laser beam.
According to another aspect of the present invention, a ceramics body is prepared by a ceramics pla~e obtained by molding raw materials and at least preliminarily sintering the same. In other words, a substrate itself is prepared by a ceramics material of superconductive composition, in order to form a superconducting circuit on the surface of the substrate. According to this method, the surface of a substrate of ceramics, being obtained by molding superconductive ceramics raw materials and at least preliminarily sintering the same, i5 locally heated by a laser beam, to form an interconnection part of superconductive ceramics on the substrate.
According to such an aspect, the surface of the substrate of ceramics being obtained by molding the superconductive ceramics raw materials and at least preliminarily sintering the same is so locally heated by : the laser ~eam as to improve heating~melting efficiency, whereby a homogeneous interconnection part of superconductive ceramics having a high critical temperature can be formed on a surface part of the locally heated substrate.
The interconnection part can be f inely provided through such local heating by the laser beam, while the interconnection part of superconductive ceramics thus f ormed is integrated with the substrate.
~ 3 0~
The aforementioned preliminary sintering step may be performed in various atmospheres, while the same is preferably performed under presence of oxygen, e.g., in an oxygen-containing atmosphere with oxygen partial pressure of 150 to 760 mmHg, in order to obtain a homogeneous composite oxide while preventing decomposition or reduction o~ the raw materials. Preliminary sintering conditions such as a heating temperature and a heating time are appropriately selected in response to the raw materials as employed etc.
Even if superconductive ceramics raw materials as employed have high melting points, a composite oxide of a low melting point can be obtained through solid phase reaction in a solid phase state by performing the aforementioned series of steps at least once. Raw material of superconductive ceramics, generally having high melting points, must be sintered at a high .
1307~16 temperature for a long time. Even if the materials are sintered under such conditions, the surface parts and the inner parts of the ceramics material are not necessarily homogeneous. However, a ceramics material being homogeneous to the interior can be obtained by performing the aforementioned series of steps at least once. In order to prepare a ceramics material composed of Y0 3BaCu~ 7O3 by employing Y2O3, BaCO3 and CuO, for example, the raw materials, having high melting points of 1200 to 2700C and being hard to melt, must be sintered at a high temperature for a long time. Further, ranges of the melting points of the raw materials are extremely different from each other and hence sintering conditions must be set in response to the raw material having the highest melting point. Even if sintering is performed in the said conditions, it is difficult to obtain a ceramics material of homogeneous composition. However, a composite oxide of a low melting point can be generated through the aforementioned series of steps by solid phase reaction in the aforementioned preliminary sintering step. Namely, a mixture of the raw materials is subjected to compression molding, preliminary sintering and pulverizing steps to provide a desired composite oxide having a low melting point of 900 to 1400C, which is in a naxrower melting temperature range as compared with the raw materials.
9 _ -- ~307~16 Thus, the aforementioned series of steps are performed to facilitate later molding and sintering steps, as well as to obtain homogeneous ceramics powder.
The aforementioned series of steps may be performed at least once in response to the raw materials as employed and the desired composite oxide etc. Confirmation as to whether or not a desired composite oxide is generated can be made by analyzer means such as an X-ray diffractometer.
Thus, the number of times for repeating the aforementioned series of steps can be set by confirming whether or not the desired composite oxide is generated by the analyzer means in response to the raw materials as employed, the sintering conditions etc. The pulverizing step may be performed through a ball mill or the like.
The ceramics powder obtained in the aforementioned manner can be easily formed by the homogeneous composite oxide of a low melting point, and sintered under a low ;~ temperature condition.
Then, the ceramics powder obtair.ed from the aforementioned raw materials throuyh the aforementioned series of steps is molded and at least preliminarily sintered to provide a substrate of ceramics. At least the aforementioned preliminary sintering step may be performed in order to obtain an integrated substrate, while essential firing may be performed to further improve 1307ql6 integrality of the substrate. The substrate obtained in the aforementioned manner may have a low critical temperature, since the same is provided with a superconductir.g circuit by an interconnection part of superconductive ceramics having a high critical temperature by application of a laser beam. The substrate obtained by the aforementioned ceramics powder o~ a homogenous composite oxide is superconductive ancl has a high critical temperature. The critical temperature of the substrate can be controlled by adjusting the number of times for repeating the aforementioned series of steps. In the aforementioned molding step, the material can be shaped into an appropriate configuration of a block, a sheet or ` 15 the like while preliminary and essential sintering conditions are appropriately selected in response to the melting points of the raw materials and the aforementioned ceramics powder and desired characteristics of the substrate.
~; 20 BRIEF DESCRIPTION OF THE DRA~INGS
Pig. l schematically illustrates an exemplary step of performing heat treatment by a laser beam in a method according to the presen~ invention;
Fig. 2 is a schematic sectional view showing a ceramics body which is formed with a superconducting j:
,,, ) ~,~ , . ., .;
- 1307ql6 circuit according to a first embodiment of the present invention;
Fig. 6 is a perspective view showing a st~te during scanning of a laser beam in a fifth embodiment (Example 2) of the present invention;
Fig. 9 i5 a perspectivç view showing a state of measuring temperature-resistance characteristics in case of connecting one of four terminals to a part not exposed to the laser beam;
1 30-19 ~ 6 Fig. 10 is a perspective view for illustrating a sixth embodiment (Example 3) of the present irlvention;
Fig. 11 illustrates current-voltage characteristics of a bridge type Josephson junction device obtained by the sixth embodiment (E~ample 3) of the present invention; and Fig. 12 is a perspective view showing a seventh embodiment (Example 4) of the present invention.
In order to form a superconductive phase on the surface of a ceramics plate ser~Jing as the aforementioned substrate, the surface of the ceramics plate is preferably locally heated by a laser beam under presence of oxygen.
In more concrete terms, a laser beam is passed through a cylindrical body 2 as shown in Fig. 1 and converg~d into a focused state by a lens 3 held in the cylindrical body 2 to be applied to the suxface of a substrate 1 for heating/melting operation. ~he point of application of the laser beam is moved to form a prescribed interconnection part having a higher critical temperature of superconduction than the substrate 1. In order to supply oxygen to the surface of the substrate 1, oxygen gas or mixed gas having high oxygen partial pressure is fed to the cylindrical body 2t to be sprayed to the surface of the substrate 1 from a forward end portion of the cylindrical body 2. While the aforementioned heating/melting operation by the laser beam may be performed under various atmospheres, such operation may be performed under presence ..
~ j4`~
1 307ql 6 of oxygen in order to form a superconducting circuit having a high critical temperatuxe on the surface of the substrate 1 while preventing reduction or decomposition of an oxide etc. forming the ceramics material. The laser beam is preferably applied to the surface of the substrate 1 whil~
supplying oxygen to the substrate surface by a method of spraying oxygen gas or mixed gas having high oxygen partial pressure of 150 to 760 mmHg, for example.
Through such operation, a superconductive ceramics material having a higher critical temperature than a substrate part lb is generated in a part heated/molten by the laser beam, thereby to form a superconducting circuit consisting of the substrate part lb and an interconnection part la of superconductive ceramics which has a hi~her critical temperature than the substrate part lb, as shown in Figs. 2 and 3. Further, a low-temperature operating device 4 such as SQUID (superconducting quantum interference device) or GaAs HEMT (high electron mobility transistor) can be placed on an interconnection part la of a substrate 1 as shown in Fig. 4 to serve as an element through the interconnection par~ la of superconductive ceramics. Thus, according to this aspect, a ceramics body is prepared by a ceramics plate obtained by molding raw I
... ~, . . .
, 1307~16 materials and at least preliminarily sintering the same to serve as a substrate, thereby to form a superconducting circuit by applying a laser beam on the surface of the substrate. Thus, a substrate integrated with a superconducting circuit can be obtained so that the substrate and the superconducting circuit may not be separately prepared, whereby manufacturing steps can be simplified.
Further, depth of a superconductive phase can be adjusted by changing energy of the laser beam. The inventive method is effectively applied to manufacturing of a switching element, a memory element, a magnetic flux sensor, an amplifier element, a thin motor etc., which are employed in various fields such as those o~ electronics and power application.
In the aforementioned first aspect of the present invention, a ceramics body to be provided with a superconducting circuit is a film formed on a substrate.
According to this aspect, the circuit can be simply formed as compared with a conventional method of forming a circuit by performing ion sputtering and partially scraping off a .~, .,,; "
thin film, while an interconnection part of the circuit can be finely worked in width.
According to the aforementioned another aspect of the present invention, a ceramics body to be provided with a superconducting circuit is prepared by a ceramics plate, also serving as a substrate, obtained by molding raw materials and at least preliminarily sintering the same.
Accordinq to this aspect, the superconducting circuit can be integrally formed on the surface of the substrate so that the same may not be prepared separately from the substrate, whereby manufacturing steps can be simplified.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompa~ying drawings.
Description is now made on an embodiment employing a ceramics body formed by a ceramics plate which is obtained by molding raw materials and at least pr~liminarily sintering the same.
Example 1 Prescribed amounts of powder materials of Y2O3, BaCO3 and CuO, being raw materials for a ceramics body, were .
. ' .', , :
weighed and mixed with each other. Such mixed powder W2Scompression-molded into a sheet at the normal temperature in the atmospheric air of 100 atm., and preliminarily sintered in a mixed gas atmosphere of oxygen gas and nitrogen gas with oxygen gas partial pressure of 200 mmHg at 940C for 24 hours. A preliminarily sintered ceramics body thus obtained was pulverized by a ball mill. Such series of steps were repeated until a composite oxide of Y0 3BaCuO 7O3 was confirmed by X-ray diffraction.
Ceramics powder of the composite oxide obtained in the aforementioned manner was compression-molded into a sheet and sintered in the atmospheric air at 800C for two hours, to prepare a substrate. A beam of 1 to 10 W from a C2 laser was converged to about 0.1 mm in diameter to ~- 15 locally heatJmelt the surface of the substrate while spraying oxygen gas onto the substrate surface. Such a local heating point was moved to form a prescribed interconnection part. Finally heat treatment was performed under an oxyyen atmosphere in a heat treating furnace at 700C for five hours.
As the result of measurement of critical temperatures based on electric resistance, the interconnection part heated/molten by the laser beam superconducted at a temperature of not more than 80 K while the substrate part superconducted at a temperature of not more than 30 K, as 1 3()791 6 shown in Fig. 5. Thus, it has been recognized that the substrate part relatively entered a non-superconductive phase and the interconnection part of a superconducting circuit entered a superconductive phase by cooling the substrate in a temperature range o~ 30 to 80 ~.
Example 2 A film composed of YBal 8Cu2 7x having (100) surface of strontium titanate of 15 x 15 mm in size as a substrate surface was formed ln thicXness of 0.5 ~m by magnetron high-frequency sputtering. An atmosphere gas was prepared by argon-o~ygen mixed gas containing 10 % of ox~gen, with pressure of 1 x 10 2 torr. and a substrate temperature of 600C. A film thus formed was not directly superconductive.
~ laser beam was applied onto the film as shown in Fig. 6. Re~erring to Fig. 6, numeral 11 indicates the substrate, numeral 12 indicates the film, numeral 13 indicates the laser beam, numeral 14 indicates a lens of zinc selenide (ZnSe), and numeral 15 indicates a part exposed to the laser beam in hatching. It is to be noted that, in Fig. 6, the film 12 is shown in an enlarged manner as compared with actual size. The laser beam 13 was emitted ~rom a C02 laser in wavelength of 10.6 ~m with , power of 20 W/cm~ and a scanning rate of ~.01 mm/sec. The ZnSe lens 14 was adapted to converge the laser beam 13 to be in a spot diameter of 1 mm.
~ platinum-platinum rhodium thermocouple was placed in the vicinity of the exposed part 15 to measure the temperature thereof, which was 8~0 to 940C.
An exposed part 15 as shown in Fig. 7 was formed on the film 12 by the aforementioned scanning of the laser beam 13. As shown in Fig. 8, copper wires were interconnected to the exposed part 15 to measure temperature-resistance characteristics. The so-called critical temperature showing 10 7 Q, the limit of the measuring apparatus, was 78 K.
When one of four terminals was interconnected to a part not exposed to the laser beam as shown in Fig. 9, no superconductivity was recognized even at the temperature o~ liquid helium (4 X).
Thus, it has been confirmed that only the exposed part 1~ was in a superconductive phase. Referring to Figs. 6 to 9, identical reference numerals indicate the same components.
A film prepared under the conditions of this Example was subjected to heat treatment with a substrate under presence of oxygen at 900C for two hours without exposure to a laser beam, whereby the so-called critical temperature, at which electric resistance substantially reached zero, was 84 K.
Example 3 ~s shown in Fig. 10, a film 22 was formed on a substrate 21 in a similar manner to Example 2, and an exposed part 25 was formed in the film 22 by application of a laser beam. Wide portions 25a of the exposed part 25 were formed by scanning of the laser beam in a spot diameter of 1 mm at a scanning rate of 1 mm/sec. A narrow junction portion 25b was formed by scannin~ of the laser beam with a spot diameter of 1~ ~m at a scanning rate of 10 mm/sec. Finally heat treatme~t was performed under an oxygen atmosphere in a furnace at 800C for two hours.
Copper wires were interconnected to the wide portions 25a on both sides of the junction portion 25b -- ~0 ---respectively, to measure current-voltage characteristics at 77 K. Fig. ll shows the result. As obvious from Fig.
ll, it has been confirmed that the junction portion 25b of the exposed part 25 served as a bridge type Josephson device.
Example 4 Description is now made on the case of employing lanthanum as an element belon~ing to the group IIIa of the periodic table, strontium as an element belonging to the group IIa of the periodic table and copper as an element belonging to the group Ib of the periodic table. A
ceramics substrate 32 was set in a vacuum chamber to be heated to about lO0 to 1000C. Then, crucibles containing lanthanum, stxontium and copper were heated to lO0 to 1000C respectively. After vapor pressures of the respective elements were thus obtained to some extent, oxygen was introduced from a nozzle 35 provided in the vicinity of the substrate 32 and finally shutteres provided in upper portions of vaporization sources of the respective elements were opened, thereby to perform vapor deposition on the substrate 32.
~ Such a substrate 32 can be prepared by a ceramics ; plate of Al2O3, BN or the like.
Thereafter a thin film 31 thus formed was exposed to a laser bec~m 33, which was restricted in beam diameter, in , the air or with spraying of oxygen as shown in Fig. 12.
Thus, a part of the thin film 31 exposed to the laser beam 33 was heated to about 1000C to be sintered, thereby to provide a superconductive phase 34 being in superconductive crystal structure.
Although the present invention has been described and illustrated in detail, it is clearly understood ~hat the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
1. A method of forming a superconducting circuit comprising the steps of:
preparing a crystalline ceramics copper oxide body which is capable of being converted by heat treatment from a phase which is not superconducting at a particular working temperature into phase superconducting at the working temperature; and performing such a heat treatment on a part of said crystalline ceramics body by applying a laser beam to said crystalline ceramics body while in the presence of oxygen, to convert the part into said superconductive phase, thereby forming a superconducting circuit consisting of said superconductive phase and said non-superconductive phase on said crystalline ceramics body.
2. A method of forming a superconducting circuit in accordance with claim 1, wherein:
3. A method of forming a superconducting circuit in accordance with claim 1, wherein:
said ceramics body is a ceramics plate obtained by molding raw materials and at least preliminary sintering the same.
4. A method of forming a superconducting circuit in accordance with claim 3, wherein:
said ceramics plate is prepared by performing a series of steps of molding, preliminary molding and pulverization of a preliminary sintered substance at least one after mixing of said raw materials to obtain ceramics powder, molding said ceramics powder and at least preliminary sintering the same.
5. A method of forming a superconducting circuit in accordance with claim 1, wherein:
said laser beam is admitted from a CO2 laser or a YAG laser.
6. A method of forming a superconducting circuit in accordance with claim 1, wherein:
said raw materials for said ceramic body contain at least two elements selected from groups Ia, IIa and IIIa of the periodic table, copper and oxygen.
7. A method of forming a superconducting circuit in accordance with claim 6, wherein:
8. A method of forming a superconducting circuit in accordance with claim 7, wherein:
9. A superconducting circuit consisting of a superconductive phase and a non-superconductive phase formed by the steps of:
preparing a crystalline ceramics copper oxide body of a material capable of being converted by heat treatment from a phase which is not superconductive at a particular working temperature into a phase which is superconductive at the working temperature and applying a laser beam to said crystalline ceramics body in the presence of oxygen, to perform said heat treatment on a desired part of said crystalline ceramics body, thereby to convert said desired part of said crystalline ceramics body into said superconducting phase.
10. A superconducting circuit in accordance with claim 9, wherein.
the raw materials for said crystalline ceramics body contain at least two elements selected from groups Ib, IIb, IIIb of the periodic table, copper and oxygen.
11. A superconducting circuit in accordance with claim 10, wherein:
said raw materials for said crystalline ceramics body contain at least copper oxide.
12. A superconducting circuit in accordance with claim 11, wherein:
crystalline ceramics body is prepared of oxides yttrium, barium and copper.
CA000562820A 1987-03-30 1988-03-29 Method of forming superconducting circuit Expired - Fee Related CA1307916C (en)
JP79361/1987 1987-03-30
JP91123/1987 1987-04-14
JP208881/1987 1987-08-22
CA1307916C true CA1307916C (en) 1992-09-29
CA000562820A Expired - Fee Related CA1307916C (en) 1987-03-30 1988-03-29 Method of forming superconducting circuit
1988-03-24 JP JP63071487A patent/JP2855614B2/en not_active Expired - Lifetime
1988-03-29 DE DE19883851248 patent/DE3851248D1/en not_active Expired - Fee Related
1988-03-29 EP EP88105111A patent/EP0285106B1/en not_active Expired - Lifetime
1988-03-29 DE DE19883851248 patent/DE3851248T2/en not_active Expired - Lifetime
1988-03-29 CA CA000562820A patent/CA1307916C/en not_active Expired - Fee Related
JP2855614B2 (en) 1999-02-10
DE3851248D1 (en) 1994-10-06
DE3851248T2 (en) 1995-04-13
JPH01144689A (en) 1989-06-06
EP0285106A2 (en) 1988-10-05
EP0285106B1 (en) 1994-08-31
EP0285106A3 (en) 1989-08-23
Wada et al. 1990 Phase stability and decomposition of superconductive YBa2Cu4O8
Sung et al. 1991 Synthesis and Preparation of Lanthanum Aluminate Target for Radio‐Frequency Magnetron Sputtering
Schieber 1991 Deposition of high temperature superconducting films by physical and chemical methods