A superconducting material is a material that exhibits properties of zero resistance and repulsion of magnetic field lines at low temperatures. 28 elements and thousands of alloys and compounds have been found to be superconductors. Niobium superconducting material.
Zero resistance. When a superconducting material is in a superconducting state, its resistance is zero and it can transmit power without loss. If a magnetic field is used to induce an induced current in a superconducting ring, the current can be maintained without attenuation. This "continuous current" has been observed many times in experiments. Diamagnetism, when the superconducting material is in the superconducting state, as long as the external magnetic field does not exceed a certain value, the magnetic force line cannot penetrate, the magnetic field in the superconducting material is always zero. Critical temperature, the temperature at which the superconducting material changes from normal state to superconducting state (or vice versa) when the external magnetic field is zero, expressed as Tc. Tc value varies with material. The lowest Tc of the measured superconducting material is tungsten at 0.012k. By 1987, the maximum critical temperature had increased to about 100K.
28 elements had super conductivity under atmospheric pressure, and the Tc of Nb was the highest, 9.26k. The practical application in electrical engineering is mainly niobium and lead (Pb, Tc= 7.201k), which have been used in the manufacture of superconducting alternating power cables, high-q resonator and so on. All the properties of superconducting materials can be improved. For example, niobium zirconium alloy (nb-75zr), which was first applied, has a Tc of 10.8k and a Hc of 8.7 specie. Niobium and titanium alloys have since been developed, although Tc is slightly lower, Hc is much higher and can carry more current in a given magnetic field. Its performance is nb-33ti, Tc=9.3K, Hc=11.0 t; Nb-60ti, Tc=9.3K, Hc=12 ter (4.2K). The performance of nb-60ti-4ta is further improved, Tc= 9.9k, Hc= 12.4t (4.2k). The performance of nb-70ti-5ta is Tc=9.8K, Hc=12.8 t.
