Niobium-titanium alloy superconductor has been widely used in thousands of known superconductors due to its excellent comprehensive properties. It is the key material in superconducting magnets for medical NMR and large scientific devices. Niobium titanium alloy is a typical binary alloy composed of transition group elements. In a previous study of the high-entropy alloy superconductor (TaNb)0.67(HfZrTi)0.33, which is composed of multiple transition group metal elements, it was found that at ultra-high pressure (pressure above million atmospheres is ultra-high pressure, 1 million atmospheres =100 GPa), Because niobium and titanium are the main components of this high entropy alloy, the study of the superconductivity of niobium titanium alloy under ultra-high pressure can deepen the understanding of the micro mechanism of superconductivity of high entropy alloy.
The superconductivity of niobium-titanium alloy superconductor under ultra-high pressure has been studied systematically. It is found that niobium-titanium alloy maintains zero resistance superconductivity at pressures up to 261.7GPa, which indicates that niobium-titanium alloy is the most pressure-resistant superconductor known so far. This pressure is the highest pressure for which superconductivity has been reported. The transition temperature of niobium-titanium alloy superconductor is increased from 9.6K to 19.1K under this pressure.
The above research reveals that the superconductivity of alloy superconductors composed of transition metal elements can resist large deformation and exist stably under high pressure, which is in sharp contrast to the highly sensitive superconductivity of copper oxide and iron based superconductors to volume changes. It is also obviously different from the behavior that the superconducting transition temperature of the post-transition metallic element superconductor (D-electron full shell in valence electrons) decreases with volume compression.
In addition, in terms of experimental technology, this research combines successfully the experiment on the large scientific device such as high pressure extreme conditions, strong magnetic field and synchrotron radiation, which provides a new model for our country to jointly carry out frontier scientific research by using its own large scientific device.
