Superconductor technology: apparatus – material – process – High temperature – per se – Having tc greater than or equal to 150 k
Patent
1991-07-24
1993-08-31
Lieberman, Paul
Superconductor technology: apparatus, material, process
High temperature , per se
Having tc greater than or equal to 150 k
156DIG63, 156DIG70, 156DIG78, 423596, C01F 1102, C01F 1700, C01G 1500, C01G 3702
Patent
active
052409023
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a substrate of a single crystal composed of an oxide, a super-conductive device having the substrate of a single crystal used therefor and a method of producing a super-conductive device.
BACKGROUND ART
It has been heretofore said that a super-conductive phenomenon appears with a most peculiar nature among various electromagnetical natures exhibited by a certain material. In view of the foregoing nature, it is expected that practical application of the super-conductive phenomenon will largely be widened in near future by utilizing its natures such as complete electrical conductivity, complete antimagnetism, quantification of a magnetic flux or the like.
A high speed switching element, a detecting element having high sensitivity and a magnetic flux measuring instrument having high sensitivity can typically be noted as electronic devices for which the aforementioned super-conductive phenomenon is utilized, and it is expected that these devices are practically used in the wide range of application.
For example, a thin film of Nb.sub.3 Ge deposited on the surface of a substrate by employing a plasma spattering method can be noted as a typical super-conductive material which has been hitherto used for a conventional super-conductive device. However, since the thin film of Nb.sub.3 Ge has a critical superconductivity temperature of about 23.degree. K., the super-conductive device can be used only at a temperature lower than that of a liquid helium. For this reason, when the liquid helium is practically used for the super-conductive device, there arises a significant problem that a cooling cost and a technical burden to be born are increased because of a necessity for installing an equipment and associated instruments for cooling and liquidizing a helium gas with the result that practical use of the super-conductive device not only in the industrial field but also in the household field is obstructed. Another problem is that an absolute quantity of helium source is small and limited.
To obviate the foregoing problems, a variety of endevors have been made to provide a super-conductive material having a higher critical superconductivity temperature. Especially, in recent years, remarkable research works have been conducted for providing a super-conductive thin film composed of an oxide having a higher superconductivity temperature. As a result derived from the research works, a critical superconductivity temperature is elevated to a level of 77.degree. K. This makes it possible to practically operate a super-conductive device having the foregoing super-conductive thin film used therefor while using an inexpensive liquid nitrogen.
To form such a super-conductive thin film composed of an oxide as mentioned above, a spattering method or a vacuum vaporizing/depositing method has been heretofore mainly employed such that the super-conductive thin film is deposited on the surface of a substrate of a single crystal of MgO or SrTiO.sub.3 which is preheated to an elevated temperature.
In addition, with respect to a single crystal employable for the substrate, attention has been paid to a sapphire, YSZ, a silicon, a gallium arsenide, LiNbO.sub.3, GGG, LaGaO.sub.3, LaAlO.sub.3 or the like.
However, it has been found that the conventional method of forming a super-conductive thin film while having a substrate of a single crystal of MgO or a substrate of a single crystal of SrTiO.sub.3 used therefor as a substrate has problems that a critical superconductivity current (Jc) can not stably be elevated, and moreover a critical superconductivity temperature (Tc) is kept unstable.
To form an epitaxial film having excellent properties, it is necessary that a material employable as a substrate satisfactorily meets the following requirements. (I) The lattice constants of substrate crystals are close to that of thin film crystals. (II) A quality of the thin film is not degraded due to mutual diffusion to and from the substrate during an operation for growing an epitaxial thin film. (I
REFERENCES:
patent: 3959006 (1976-05-01), Herrnring
patent: 4199396 (1980-04-01), Brandle
patent: 4379853 (1983-04-01), Mateika
patent: 4454206 (1984-06-01), Mateika
patent: 4483734 (1984-11-01), Sakaguchi
patent: 4820445 (1989-04-01), Piekarczyk
Boyd John
Kabushiki Kaisha Komatsu Seisakusho
Lieberman Paul
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