Low-resistance connection body for high-temperature superconducting wire material and connection method

A low-resistance connection body for a high-temperature superconducting wire, in which a first high-temperature superconducting wire including a first high-temperature superconducting layer comprising RE1Ba2Cu3O7-δ and a second high-temperature superconducting wire including a second high-temperature superconducting layer comprising RE2Ba2Cu3O7-δ are connected to each other via a high-temperature superconducting bulk body comprising RE′Ba2Cu3O7-δ, wherein

• each of RE1, RE2, and RE′ being one or a plurality of rare earth elements, and an element or composition of RE′ being different from that of RE1 or RE2;
• melting points of the first and second high-temperature superconducting layers are higher than a melting point of the high-temperature superconducting bulk body;
• the first and second high-temperature superconducting layers and the high-temperature superconducting bulk body are in contact at connection sites of the first high-temperature superconducting wire and the second high-temperature superconducting layer of the second high-temperature superconducting wire and the high-temperature superconducting bulk body;
• and
• surfaces of the high-temperature superconducting bulk body that are in contact with the first and second high-temperature superconducting layers are crystallized into single crystal, and other portions of the high-temperature superconducting bulk body is crystallized into polycrystal due to crystal growth.

A low-resistance connection method for a high-temperature superconducting wire, for connecting a high-temperature superconducting wire including a high-temperature superconducting layer with a high-temperature superconducting bulk body, the melting point of which is lower than that of the high-temperature superconducting layer,

• the method comprising:
• a temperature rise step of heating the high-temperature superconducting bulk body comprising REBa2Cu3O7-δ up to a temperature that is equal to or higher than a melting point of the high-temperature superconducting bulk body and lower than a melting point of the high-temperature superconducting layer comprising RE′Ba2Cu3O7-δ, each of RE and RE′ being one or a plurality of rare earth elements, and an element or composition of RE′ being different from that of RE;
• and
• a crystal growth step of performing crystal growth on the high-temperature superconducting bulk body in a state where a liquid phase portion of the high-temperature superconducting bulk body and the high-temperature superconducting layer are in contact with each other, the crystal growth leading to a formation of a single crystal at a contact surface of the high-temperature superconducting bulk body and a polycrystal at other portions of the high-temperature superconducting bulk body.

A low-resistance connection method for a high-temperature superconducting wire, for connecting a first high-temperature superconducting wire including a first high-temperature superconducting layer comprising RE1Ba2Cu3O7-δ and a second high-temperature superconducting wire including a second high-temperature superconducting layer comprising RE2Ba2Cu3O7-δ with a high-temperature superconducting bulk body comprising RE′Ba2Cu3O7-δ, the melting point of which is lower than those of the first high-temperature superconducting layer and the second high-temperature superconducting layer, each of RE1, RE2, and RE′ being one or a plurality of rare earth elements, and an element or composition of RE′ being different from that of RE1 or RE2;

• the method comprising:
• a temperature rise step of heating the high-temperature superconducting bulk body up to a temperature that is equal to or higher than a melting point of the high-temperature superconducting bulk body and lower than melting points of the first and second high-temperature superconducting layers;
• and
• a crystal growth step of performing crystal growth on the high-temperature superconducting bulk body in a state where a liquid phase portion of the high-temperature superconducting bulk body and the first and second high-temperature superconducting layers are in contact with each other, the crystal growth leading to a formation of a single crystal at contact surfaces of the high-temperature superconducting bulk body and a polycrystal at other portions of the high-temperature superconducting bulk body.