It has long been discovered that when the temperature drops to near absolute zero, the chemical properties of some substances suddenly change, becoming a "superconductor" with almost no resistance. The temperature at which matter begins to have this strange "superconducting" property is called the critical temperature. It goes without saying that the critical temperature of various substances is not the same.
You know, very low temperature is not easy to get, people pay a huge price for it; The closer you get to absolute zero, the greater the cost. So our requirement for superconducting materials, of course, is that the higher the critical temperature, the better.
Niobium is one of the elements with the highest critical temperature. Alloys made of niobium, with critical temperatures as high as 18.5 to 21 degrees Celsius, are the most important superconducting materials.
One experiment has been to take a metal niobium ring, which is cold enough to be superconducting, turn on and off an electric current, and then seal off the whole device to keep it cold. Two and a half years later, when the device was turned on, the current in the niobium ring was still flowing, and it was almost exactly the same strength as when it was first energized!
It can be seen from this experiment that superconducting materials hardly lose current. If a superconducting cable is used to transmit electricity, because it has no resistance, there will be no energy loss when the current passes through, so the transmission efficiency will be greatly improved.
