The superconductivity of titanium niobate superconductor under high pressure is studied systematically. The superconductivity of nb-ti alloy with zero resistance was found at pressures up to 261.7GPa, indicating that nb-ti alloy is the most pressure-resistant superconductor known. This pressure is the highest pressure for the existence of superconductivity that has been reported. Under this pressure, the superconducting transition temperature of the titanium-niobium superconductor increased from 9.6k to 19.1k under normal pressure, and the experimental results of the high pressure magnetoresistance of hefei high magnetic field showed that the critical magnetic field increased from 15.4t to 19T under 211GPa pressure and 1.8k temperature. This is the highest superconducting transition temperature and the highest critical magnetic field found in transition group metal element alloy superconductors. The XRD test results of the synchrotron radiation from the Shanghai light source showed that the crystal structure did not change under the pressure of 200 GPa, but its volume was compressed by about 43%.
Titanium niobate superconductor has been widely used in thousands of known superconductors because of its excellent comprehensive properties. Titanium niobium alloy is a typical binary alloy composed of transition group elements. In the previous study on the high entropy alloy superconductor (TaNb)0.67(HfZrTi)0.33 composed of multiple transition group metal elements, it was found that the alloy showed exceptionally stable superconductivity under ultra-high pressure (the pressure above one million atmospheres was ultra-high pressure, one million atmospheres =100 GPa). Since niobium and titanium are the main components of this high-entropy alloy, the study on the superconductivity of tiobium alloy under ultra-high pressure can deepen the understanding of the microscopic mechanism of superconductivity of high-entropy alloy.
The study reveals the made of the element of transition metal alloy superconductor in high pressure the superconductivity can resist deformation and stability of characteristics, it has to do with copper oxides and iron-based superconductors superconductivity sensitivity to the height of the volume change is in stark contrast, and after the transition metal elements also superconductors (valence electronic d in closed shells) of the superconducting transition temperature drop behavior are obviously different according to the volume compression. This study successfully combines experiments on large scientific devices such as high pressure extreme conditions, strong magnetic field and synchrotron radiation, providing a new example for China to use its own large scientific devices to jointly carry out frontier scientific research.
