Superconducting Flexible Organic/Inorganic Hybrid Compound Adhesives.

Superconducting pastes have been successfully developed from superconducting particles using conventional methods, thereby opening up new avenues for the application of superconducting materials. These pastes are isotropic one-component heat-curable adhesives belonging to the class of organic/inorganic hybrid compounds. In this work, superconducting pastes prepared using Nb or NbN superconducting particles are applied to solid substrates through screen printing and then heat-cured under optimized conditions to form single-phase thick films. The resistivity of the Nb and NbN films becomes zero at 7.2 and 10.5 K, respectively, indicating that both these films are superconductive at cryogenic temperatures. A large free-standing film of length approximately 130 mm is successfully developed using the NbN paste. The free-standing film is flexible and exhibits superconductivity at 11 K. These results demonstrate, for the first time, that superconductivity, flexibility, adhesion, and ink properties can be simultaneously achieved in organic/inorganic hybrid compounds.

Growth and superconductivity of niobium titanium alloy thin films on strontium titanate (001) single-crystal substrates for superconducting joints.

Aiming to introduce NbTi alloy superconducting joints for REBa2Cu3O7-δ (REBCO, RE: rare-earth element) superconducting wires, NbTi alloy thin films were deposited at room temperature on SrTiO3 (STO) (001) single-crystal substrates, which have a high lattice matching with REBCO (001). The strain, crystallinity, surface morphology, and superconducting property of the films with various thicknesses were investigated. The NbTi films grew in the orientation with (110)NbTi//(001)STO:[001]NbTi and [11-0] NbTi//[100]STO; that is, the NbTi lattices had two directions in the (110) of NbTi. The strain decreased and the crystallinity improved as the film thickness increased. The films were found to crystallize immediately at the interface between the films and substrates by cross-sectional scanning transmission electron microscopy. The flat surfaces of the films have mesh-like morphologies due to the growth of elongated NbTi grains along the [100] and [010] of the STO, reflecting the in-plane two directions of the NbTi lattices. The superconducting transition temperature of the films increased with improvement in the crystallinity of the films. The preparation of superconducting NbTi alloy thin films with sufficient crystallinity at room temperature suggested the possibility of forming the films on REBCO and the applicability of the films as superconducting joints.