Sumitomo Electric Industries, Limited

The Tokyo Electric Power Company, Incorporated

The Toyko Electric Power Company, Incorporated

Shigeru Okuda

Satoshi Takano

Noriyuki Yoshida

Noriki Hayashi

Tsukushi Hara

Kiyoshi Okaniwa

Takahiko Yamamoto

Hideo Ishii

Hajime Hitotsuyanagi

Kousou Fujino

Kenichi Sato

A thin film strongly orienting specific crystal axes is deposited on a polycrystalline or amorphous base material in accordance with laser deposition in a simpler device through a simpler process. A target is irradiated with a laser beam, for forming a thin film in accordance with laser ablation of depositing a substance scattered from the target on a base material. In order to form the thin film, prepared are conditions capable of forming a film orienting a specific crystal axis substantially perpendicularly to the base material in substantially parallel arrangement of the target and the base material. Under the conditions, a film is deposited on the base material which is inclined at a prescribed angle .theta. with respect to the target. It is possible to deposit a film strongly orienting a specific crystal axis in a plane substantially parallel to the base material surface by inclining the base material under the specific film forming conditions.

Method of forming single-crystalline thin film

Disclosed herein is a method of forming a single-crystalline thin film having excellent crystallinity on a base material without depending on the material for and crystallinity of the base material. In this method, a base material is provided thereon with a mask which can prevent chemical species contained in a vapor phase from adhering to the base material. The base material is continuously moved along arrow A, to deliver a portion covered with the mask into the vapor phase for crystal growth. Thus, a thin film is successively deposited on the portion of the base material, which is delivered from under the mask, from the vapor phase. A crystal growth end is formed on a boundary region between a portion of the base material which is covered with the mask and that which is exposed to the vapor phase, so that a crystal having the same orientation as the growth end is grown on a portion of the base material newly exposed by the movement.

An oxide superconductive wire is provided by, for example, forming an oxide superconductive layer on a tape-type flexible base. A preliminary compressive strain is applied to the oxide superconductive layer in the longitudinal direction. The remaining strain can be provided by using a base having thermal expansion coefficient larger than that of the oxide superconductive layer and by cooling the same after heat treatment, due to contraction of the base. Since the preliminary compressive strain is applied to the oxide superconductive layer, degradation of superconductivity of the oxide superconductive layer can be suppressed even if the oxide superconductive wire is bent in any direction, compared with the wire without such strain. Therefore, the oxide superconductive wire can be coiled, for example, without much degrading the superconductivity.

Oxide superconductive wire, method of manufacturing the same and the

In a method of preparing an oxide superconducting thin film having a composition of Y-Ba-Cu-O, for example, using laser ablation, which comprises the steps of applying a laser beam to a target containing components of an oxide superconductive material and depositing particles, being thereby scattered from the target, on a substrate, the oxygen gas flow rate during film deposition is set to be at least 50 SCCM, the oxygen gas pressure during film deposition is set to be 10 to 1000 mTorr, the distance between a target 9 and a substrate 10 is set to be 40 to 100 mm, the temperature of the substrate 10 is set to be 600.degree. to 800.degree. C., the energy density of a laser beam 7 on the surface of the target 9 is set to be at least 1 J/cm.sup.2, and the laser pulse energy is set to be at least 10 mJ.

In-situ laser ablation method for forming oxide superconducting films

In order to enable formation of a smooth and dense oxide superconducting film with no clear appearance of grain boundaries in a fine structure even at a high film forming rate, a laser ablation method is employed to apply a laser beam 2 to a target 1 containing components of an oxide superconductive material and deposit particles, which are thus scattered from the target 1, on a substrate 3, while gaseous oxygen is supplied from a gaseous oxygen inlet 7 toward laser plasma 6, which is generated by the application of the laser beam 2.

Method of and apparatus for preparing oxide superconducting film

In order to enable formation of a smooth and dense oxide superconducting film with no clear appearance of grain boundaries in a fine structure even at a high film forming rate, a laser ablation method is employed to apply a laser beam 2 to a target 1 containing components of an oxide superconductive material and deposit particles, which are thus scattered from the target 1, on a substrate 3, while gaseous oxygen is supplied from a gaseous oxygen inlet 7 toward laser plume 6, which is generated by the application of the laser beam 2, and to a portion of the target irradiated with said laser.

Method of preparing oxide superconducting films by laser ablation

An oxide superconducting thin film formed by laser ablation comprises a matrix formed of c-axis oriented superconducting phases and foreign phases which are different in crystal orientation from the matrix. In order to improve critical current density of the oxide superconducting thin film, preferably selected are such conditions that the size of each superconducting phase in its a-b plane is not more than 0.1 .mu.m in diameter, the size of each superconducting phase along its c-axis direction is equal to the thickness of the oxide superconducting thin film, the foreign phases at least partially pass through the oxide superconducting thin film along the direction of thickness, the size of each foreign phase is at least 0.01 .mu.m and not more than 5 .mu.m in diameter, each foreign phase has an a-axis or a c-axis perpendicularly oriented with respect to the major surface of the oxide superconducting thin film, and the like.

Superconducting thin film having a matrix and foreign phases

A laser beam (2) is applied to a target (1) of an oxide superconductive material, to deposit atoms and/or molecules which are scattered from the target (1) on a first portion (4) of a substrate (3) under an atmosphere containing oxygen for a start. Then, the substrate (3) is moved to deposit atoms and/or molecules scattered from the target (10) on a second portion, which is different form the first portion (4) of the substrate (3), under the atmosphere containing oxygen. At this time, the first portion (4) is subjected to oxygen annealing. These deposition steps are repeated until an oxide superconducting film of a desired thickness is obtained.

Fabrication of superconducting oxide films by laser ablation

Apparatus for preparing oxide superconducting film

When an oxide superconducting thin film is formed on a substrate by a vapor phase method such as laser ablation, for example, a plurality of grooves are formed on the substrate by photolithography or beam application in the same direction with an average groove-to-groove pitch of not more than 10 .mu.m, so that the oxide superconducting thin film is formed on a surface provided with such a plurality of grooves. Thus promoted is growth of crystals of the oxide superconducting thin film in parallel with the grooves, whereby respective directions of a-axes and c-axes are regulated to some extent. This improves critical current density of the oxide superconducting thin film.

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Osaka, Japan

Shigeru Okuda