SUPER CONDUCTORS - SCIENCE AND TECHNOLOGY

News: A clear picture of how mercury becomes a superconductor

 

What's in the news?

       In 1911, Dutch physicist Heike Kamerlingh Onnes discovered superconductivity in mercury. He found that at a very low temperature, called the threshold temperature, solid mercury offers no resistance to the flow of electric current.

 

Key takeaways:

       Scientists later classified mercury as a conventional superconductor because its superconductivity could be explained by the concepts of Bardeen-Cooper-Schrieffer (BCS) theory.

 

Bardeen-Cooper-Schrieffer (BCS) Theory:

       In BCS superconductors, vibrational energy released by the grid of atoms encourages electrons to pair up, forming so-called Cooper pairs.

       These Copper pairs can move like water in a stream, facing no resistance to their flow, below a threshold temperature.

       The researchers accounted for the relationship between an electron’s spin and momentum; they could explain why mercury has such a low threshold temperature (around –270°C).

       Coulomb repulsion:

       One electron in each pair in mercury occupied a higher energy level than the other. This detail reportedly lowered the Coulomb repulsion (like charges repel) between them and nurtured superconductivity.

 

Super Conductors:

       Superconducting materials show zero electrical resistance at low temperatures, which allows them to conduct 'supercurrents' without dissipation.

       A superconductor is a material that achieves superconductivity, which is a state of matter that has no electrical resistance and does not allow magnetic fields to penetrate.

       An electric current in a superconductor can persist indefinitely.

       Superconductivity can typically be achieved at very cold temperatures.

       Superconductors can be metals, ceramics, organic materials, or heavily doped semiconductors - Only criteria is that material should conduct electricity without resistance. Popular superconductors are Lead and Mercury.

 

Application:

       Superconducting electromagnets are also used in maglev trains, experimental nuclear fusion reactors and high-energy particle accelerator laboratories.

       Superconductors are also used to power railguns and coilguns, cell phone base stations, fast digital circuits and particle detectors.

       It is also used in quantum computers.