GB2247883A - Superconducting spinel materials - Google Patents
Superconducting spinel materials Download PDFInfo
- Publication number
- GB2247883A GB2247883A GB9119649A GB9119649A GB2247883A GB 2247883 A GB2247883 A GB 2247883A GB 9119649 A GB9119649 A GB 9119649A GB 9119649 A GB9119649 A GB 9119649A GB 2247883 A GB2247883 A GB 2247883A
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- GB
- United Kingdom
- Prior art keywords
- time interval
- making
- group
- superconducting material
- superconducting
- Prior art date
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- 239000000463 material Substances 0.000 title claims abstract description 16
- 229910052596 spinel Inorganic materials 0.000 title claims abstract description 7
- 239000011029 spinel Substances 0.000 title claims abstract description 7
- 239000013078 crystal Substances 0.000 claims abstract description 4
- 230000000737 periodic effect Effects 0.000 claims abstract description 3
- 239000000203 mixture Substances 0.000 claims description 8
- 239000002887 superconductor Substances 0.000 claims description 7
- 239000008188 pellet Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 239000006104 solid solution Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 5
- 239000010936 titanium Substances 0.000 claims 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical group [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical group [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 claims 1
- 229910052749 magnesium Inorganic materials 0.000 claims 1
- 239000011777 magnesium Substances 0.000 claims 1
- 229910052719 titanium Inorganic materials 0.000 claims 1
- 230000007704 transition Effects 0.000 description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 229910000807 Ga alloy Inorganic materials 0.000 description 2
- 229910000846 In alloy Inorganic materials 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 229910012636 LiTi204 Inorganic materials 0.000 description 1
- 229910017676 MgTiO3 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000000627 alternating current impedance spectroscopy Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910001179 chromel Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite 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
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000002411 thermogravimetry 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
- C04B35/46—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 titanium oxides or titanates
-
- 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
- C04B35/46—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 titanium oxides or titanates
- C04B35/462—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 titanium oxides or titanates based on titanates
- C04B35/465—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 titanium oxides or titanates based on titanates based on alkaline earth metal titanates
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N60/00—Superconducting devices
- H10N60/80—Constructional details
- H10N60/85—Superconducting active materials
- H10N60/855—Ceramic superconductors
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
A superconducting material comprises a spinel structure crystal including an element from group II and an element from group IVB of the periodic table.
Description
Superconducting materials
This invention relates to superconducting materials.
There has been much recent interest in copper oxide superconductors; however, the first oxide superconductors to be discovered with critical temperature (Tc) above 40K, Ba(Bi , Pb)09 and LiTi204, contained no copper Liti204, which has the cubic spinel structure and an average Ti valence of 3.5, exhibits a superconducting critical temperature of 13 K. Superconductivity has been observed for a range of compositions, close to x . 0, in the solid solution series Li During a recent investigation of the spinel solid solution series Mg2TiO4 - MgTi204, a resistive transition was observed at -500K for compositions with an average Ti valence close to 3.3.
This transition was reproduced in samples from several batches.
According to the present invention there is provided a superconducting material comprising a spinel structure crystal including an element from group II and an element from group IVB or the periodic table.
The invention will now be particularly described with reference to the accompanying drawings, in which:
Figure 1 is a plot of resistivity versus temperature for
a freshly prepared sample of Mg1#421Ti 1.57904, x.3.267, with In/Ga electrodes; and
Figure 2 is a plot of resistance versus temperature for
an x.3.267 sample, with In/Ga electrodes under
various conditions.
Samples of composition Mg2~yTil+yO4 with average Ti valence x, XD (4-2y)/(y+l), were prepared using the following procedure. Appropriate quantities of MgO, TiO2 and Ti were weighed out, ground together with acetone in an agate mortar and pressed into pellets. The pellets were wrapped in graphite foil and placed in the centre of an alumina tube furnace under a constant flow of argon. Particular care was taken to minimise any diffusion of air into the gas stream, using metal tubing and teflon seals. Temperature was increased to 13500C over a period of 3 hours and the samples fired for 16 hours. The temperature was then reduced to room temperature over 4 hours and the samples removed from the furnace.
Phase purity was checked by powder X-ray diffraction using a
Guinier-Hagg camera. Samples with average Ti valence close to 3.3, or less, were generally almost single phase. A small amount of second phase, < 5%, with an X-ray diffraction pattern similar to that for MgTiO3, was sometimes detected. Further reaction was not found to increase phase purity, instead the amount of second phase present was often observed to increase, probably due to oxidation; A systematic variation in lattice parameter with composition was observed, with a value of 8.482 ..002 A for x=3.267. The observed lattice parameters were consistent with reported values for Mg2TiO4, 8.445, and MgTi2O4, 8.502. Thermogravimetric analysis confirmed that the average Ti valence was, within errors, (t.05) unchanged from the starting value.
Four terminal dc resistance measurements were performed on samples mounted on a helium cryotip, using a Au (0.7% Fe)/chromel thermocouple to monitor temperature (t20K).
The sample was cooled to -150K, held for 30 minutes, then allowed to warm up at -20Kmin#1. Both current and voltage were monitored throughout. Either indium/gallium alloy or drfed silver paste electrodes were used. The room temperature resistivity was measured by two terminal ac impedance spectroscopy. The value obtained was then used to convert resistances at lower temperatures to resistivities.
On cooling the resistance of compositions with x > 3.3 rose sharply as temperature was decreased. For compositions with x < - 3 25, resistance also rose, though much less sharply, as temperature decreased. The behaviour of samples with average Ti valence between 3.25 and 3.3 was dependent upon sample history; however, compositions with x=3.267 and x=3.3 both showed evidence of zero resistance behaviour (Table 1). A typical resistivity temperature curve for a freshly prepared sample of x 1 3.267, shows a transition from zero resistance to semiconducting behaviour between 51.5 and 600K, Figure 1. At 150K, it was possible to pass up to 1 A cm~2 without any detectable voltage, indicating a resistivity of less than lOpohm-cm.
Figure 2 illustrates the deterioration of the zero resistance properties on standing. Curve 1 shows a resistance versus temperature plot for a sample allowed to to stand for three days in a vacuum desiccator (#10T) The 500K transition is still apparent; however, a second transition at about 450K was also observed with a low temperature tail indicative of weak link behaviour. In this condition the critical current was quite low with ohmic behaviour being observed for currents above 100 pA cm~2 at 150K.On standing for a further two days, the resistive transition could no longer be observed on cooling (curve 2), instead, for temperatures below 700K,the contact resistance became too high for the voltage source (- < 100V) to drive a significant current (1spa). On taking this sample, removing the electrodes and firing for 16 hours at 13000C under flowing argon, the original resistive behaviour was regenerated, (curve 3 figure 2). It was found that if the samples were stored in a good vacuum (#10-3T), the resistive transition could be preserved, unchanged, for several days.
When silver was used as electrode material, contact resistances were very much higher than for In/Ga alloy electrodes. Although similar resistive transitions were observed using Ag for both x=3.267 and x=3.3 (table 1), it was not possible to measure the resistance through the maximum of the transition.
The observed degradation in conducting properties on standing indicates that this zero resistance behaviour is associated with a phase or state highly sensitive to the presence of oxygen or water vapour. It may be that this behaviour is critically dependent upon the degree of oxidation of the spinel phase or of a surface layer, or it may be due to a metastable state that transforms rapidly in the presence of oxygen or water vapour. No significant changes in the X-ray powder diffraction pattern could be detected, however.
TABLE 1 Summary of Resistance versus Temperature Measurements.
x Electrode Tc,onset Tc(R=O) Resistance Sample
/ K / K Maximuma age
/ ohms
3.267 In/Ga 60 51.5 150 < 1 hour
61, 47 50b, 45 300 3 days
> 600 5 days
51 62 200 < 1 hourC
Ag ?60 33 > 100 1 hour
3.3 In/Ga 38 30b,d 200 1 day a. 40 ohm corresponds to -1 ohm-cm b. Extrapolated value c. After 16 hour Ar anneal at 13000C d. A constant resistance value of 0.5 ohm was observed below 380K
Claims (11)
- CLAIMS 1. A superconducting material comprising a spinel structure crystal including an element from group II and an element from group IVB or the periodic table.
- 2. A superconducting material as claimed in claim 1 wherein the group II element is magnesium.
- 3. A superconducting material as claimed in either claim 1 or claim 2 wherein the group IVB element is titanium.
- 4. A superconducting material as claimed in claim 1 wherein the crystal comprises a solid solution series Mg2TiO4 - MgTi2O4.
- 5. A superconducting material as claimed in claim 1 comprising samples of composition Mg2~yTil+yO4 with average Ti valence x, x . (4-2y)/(y+l)
- 6. A superconducting material as claimed in claim 6 wherein the average valence of Ti is substantially equal to 3.3.
- 7. A method of making a superconductor material comprising the steps of mixing together appropriate quantities of an oxide of a group II metal, and oxide of a group IVB metal and a group IVB metal and forming pellets thereof, heating said pellets over a first time interval to an elevated temperature, holding said pellets at said elevated temperature for a second time interval and reducing said pellets to room temperature over a third time interval.
- 8. A method of making a superconductor material as claimed in claim 7 wherein said elevated temperature is 13500C.
- 9. A method of making a superconductor material as claimed in claim 8 wherein the first time interval is three hours.
- 10. A method of making a superconductor material as claimed in claim 8 wherein the second time interval is sixteen hours.
- 11. A method of making a superconductor material as claimed in claim 8 wherein the third time interval is four hours.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB909020115A GB9020115D0 (en) | 1990-09-14 | 1990-09-14 | Superconducting materials |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9119649D0 GB9119649D0 (en) | 1991-10-23 |
| GB2247883A true GB2247883A (en) | 1992-03-18 |
| GB2247883B GB2247883B (en) | 1994-10-05 |
Family
ID=10682203
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB909020115A Pending GB9020115D0 (en) | 1990-09-14 | 1990-09-14 | Superconducting materials |
| GB9119649A Expired - Fee Related GB2247883B (en) | 1990-09-14 | 1991-09-13 | Superconducting materials |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB909020115A Pending GB9020115D0 (en) | 1990-09-14 | 1990-09-14 | Superconducting materials |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0549657A1 (en) |
| JP (1) | JPH06503796A (en) |
| KR (1) | KR930702246A (en) |
| FI (1) | FI931147L (en) |
| GB (2) | GB9020115D0 (en) |
| WO (1) | WO1992005125A1 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0296893B1 (en) * | 1987-03-28 | 1995-02-08 | Sumitomo Electric Industries Limited | Superconducting material and a process for preparing the same |
-
1990
- 1990-09-14 GB GB909020115A patent/GB9020115D0/en active Pending
-
1991
- 1991-09-13 GB GB9119649A patent/GB2247883B/en not_active Expired - Fee Related
- 1991-09-13 KR KR1019930700775A patent/KR930702246A/en not_active Withdrawn
- 1991-09-13 JP JP3515260A patent/JPH06503796A/en active Pending
- 1991-09-13 FI FI931147A patent/FI931147L/en not_active Application Discontinuation
- 1991-09-13 EP EP91916669A patent/EP0549657A1/en not_active Ceased
- 1991-09-13 WO PCT/GB1991/001572 patent/WO1992005125A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| WO1992005125A1 (en) | 1992-04-02 |
| JPH06503796A (en) | 1994-04-28 |
| FI931147A7 (en) | 1993-03-15 |
| FI931147A0 (en) | 1993-03-15 |
| FI931147L (en) | 1993-03-15 |
| EP0549657A1 (en) | 1993-07-07 |
| GB9020115D0 (en) | 1990-10-24 |
| GB9119649D0 (en) | 1991-10-23 |
| GB2247883B (en) | 1994-10-05 |
| KR930702246A (en) | 1993-09-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19950913 |