Patent Application
20080015111
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.
The present invention will be described in detail with reference to the accompanying drawings below.
As shown in
A housing 130, which has an inlet capable of being adjusted in direction, is disposed spaced apart from the crucible 120 by a predetermined interval, and a cluster beam material 131 is charged in the housing 130. The inlet of the housing 130 is formed in the shape of a nozzle 132.
A tape shaped substrate 140 on which a high temperature superconducting film is to be deposited is disposed in the front of the inlet of the crucible 120 and the inlet of the housing 130 with predetermined intervals therebetween. The substrate 140 is an oxide single crystal substrate or a metal substrate on which a buffer layer is deposited.
In this embodiment, an oxide superconducting compound may be used as the high temperature superconducting material 121, and a metal oxide may be used as the cluster beam material 131.
A typical example of the oxide superconducting compound is ABa2Cu3O7-x (wherein A is one of Y, Sm, Nd, Gd, Dy and Ho), and a typical example of the metal oxide is MgO.
It will be obvious that the materials of the present invention are not limited to the above materials, and can be applied to any usable materials.
A superconducting film is formed by spraying an auxiliary cluster beam using an evaporation method in the above apparatus. That is, the superconducting film is formed by heating the crucible 120, in which the high temperature superconducting material 121 is charged, using an electromagnetic method or by supplying the high temperature superconducting material 121 in a vapor state 122 to the substrate 140 and depositing it thereon using a method of applying an electromagnetic beam and evaporating materials. In this case, the vapor pressure of the superconducting material in a vapor state 122 is adjusted to be approximately 10−5 Torr.
At the same time, a beam of nanoparticles is sprayed onto the substrate 140 using an evaporation method of electromagnetically heating the cluster beam material 131 charged in the housing 130. That is, the cluster beam material 131 charged in the housing 130 is heated, and is formed into gas atoms 133.
The atomized cluster beam material passes through a nozzle 132 in the state of the gas atoms 133, and nanoclusters 134 are simultaneously formed due to collisions between the gas atoms. The formed nanoclusters 134 are sprayed and grown on the substrate 140, thereby forming pinning centers. Here, the vapor pressure is maintained at approximately 10−4 Torr.
The process of forming a cluster beam will be described with reference to
Generally, a high temperature superconducting film is deposited under an oxygen atmosphere, thus the cluster beam must be sprayed under an oxygen atmosphere.
As described above, a cluster beam material 131 is formed into the gas atoms 133 in a state of highly pressurized vapor, and then the formed gas atoms are sprayed through a nozzle 132. At this time, since the vapor pressure is rapidly decreased, the vapor of the gas atoms 133 is cooled. While the gas atoms 133 pass through the nozzle 132, they collide with each other and agglomerate each other, thereby forming nanoclusters.
The nozzle has a small diameter of 1 mm. Therefore, if a raw material can be oxidized and if oxides adhere to the wall of the nozzle and do not evaporate, the nozzle becomes clogged and thus the function of the nozzle is not maintained. Accordingly, the oxides must be evaporated and thus formed into vapor of the gas atoms, and then the vapor of the gas atoms must pass through the nozzle. In the present invention, the oxides are formed into the vapor of the gas atoms, and then the vapor of the gas atoms pass through the nozzle and then are sprayed on a substrate.
Even though the cluster beam material is added into the superconducting film, it must not chemically affect the superconducting film. That is, the cluster beam material must not chemically affect the formation of the superconducting film, and must not adversely affect the growth of crystal other than the formation of rod defects.
Although these materials may include various materials, MgO is typically used in the present invention.
When MgO is used as the cluster beam material, the cluster beam can be formed as follows. MgO has a vapor pressure of 0.5 Torr at a temperature of 1700° C. Mean free path of the MgO molecules at this vapor pressure is approximately 0.1 mm. Accordingly, when the diameter of the nozzle is 1 mm and the length thereof is 1 mm, the MgO molecules collide about 10 times in the spraying process. Since the MgO molecules collide while expanding, the MgO molecules are formed into nano sized clusters.
MgO is put in a Tantalum tube having several nozzles, and is heated to a temperature of 1700° C. by applying current in order to form the cluster beam.
In the present invention, the incident angle of the cluster beam particles is determined by the positional relationship between the substrate and the nozzle. If it is required to adjust the incident energy, as shown in
As shown in
As shown in
Accordingly, the pinning force of magnetic flux lines 214 is increased by the pinning centers, thereby increasing the critical current density of the superconductor.
According to the present invention, there is an advantage in that nanoparticles are formed in the superconducting film using a method of auxiliarily spraying and growing a cluster beam itself, so that the pinning force of the magnetic flux lines is increased, thereby increasing the critical current density of the superconductor.
Further, there is an advantage in that, in the process of forming the pinning centers, the density, incident angle and incident energy of the nanoparticles can be arbitrarily adjusted by changing the alignment angle of the housing, the distance between the housing and the substrate, and the heating energy, so that the pinning centers of magnetic flux lines are formed in the form of various densities and distributions, thereby increasing the critical current density characteristics in the magnetic field of the high temperature superconducting wire rod.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0066090 | Jul 2006 | KR | national |
