What makes superconductivity at liquid-nitrogen temperatures possible? And how does this work?

Answer 1

The basis of superconductivity at very cold temperatures is quantum mechanical effect.

The explanation is based on second order phase transitions, and the theory is very mathematical:

http://en.wikipedia.org/wiki/Ginzburg-Landau_theory

Superconductivity is usually associated with much colder temperatures than liquid nitrogen. However, in 1986, Bednorz and Müller discovered superconductivity in a lanthanum-based cuprate perovskite material, which had a transition temperature of 35 K. Soon after that, Paul Chu of Houston and M.K. Wu of Alabama/Huntsville replaced the lanthanum with yttrium, and raised the critical temperature to 92 K (at atmospheric pressure, the boiling point of nitrogen is 77 K.) The theoretical basis of their finding is discussed in the physics literature, and is based on the Ginzburg-Landau work.

Answer 2

Superconductivity occurs at much colder temperatures than liquid nitrogen. The quest for the Holt Grail is to get something to superconduct at the relatively warm temperature of liquid nitrogen.

Answer 3

Kind of like Ek I's answer:
Superconductivity means no energy loss. Energy loss in the movement of an electron gas comes from transfer of energy from the electrons to the surrounding material. That's why vacuum is superconductive (I think).
Another way to see superconductivity is to have a temperature so low that spin-paired electrons can exist, without being broken apart by random fluctuations. The pairs are larger in size than the atoms of the metal, so they don't bounce off them.

Answer 4

Superconductivity happens when everything is so frozen that there is no resistance in the superconductor. Because of this, many molecules are not moving, so it is easy for other thing to pass through the superconductor.

Answer 5

Basically at low temperatures some materials only very loosely hold onto their electrons. That yields a super conductor.