According
to Merriam-Webster dictionary
superconductivity is a complete disappearance
of electrical resistance in a substance,
especially at very low temperatures.
To learn about superconductors and superconductivity we must start with the basics, and that is current. Current is the stream of electrons that flow through a medium. These electrons come from the atom or molecules in the medium, and are known as conductance electrons. They do not orbit individual atoms, but instead float freely through the material.
To learn about superconductors and superconductivity we must start with the basics, and that is current. Current is the stream of electrons that flow through a medium. These electrons come from the atom or molecules in the medium, and are known as conductance electrons. They do not orbit individual atoms, but instead float freely through the material.
Solids consist of a latticework of atoms. For
a current to exist the electrons must be able
to flow through this lattice. It is this
lattice that causes resistance. The individual
atoms are vibrating and bumping into the
electrons as they move. This slows them down.
Therefore, the higher the temperature the more
vibrational energy the atoms have and the
greater resistance. This in theory would allow
us to cool any solid and make it into a
superconductor, but that is not the case.
There is a limit to most conductors.
Superconductors are different in that once the
reach their critical temperature the
resistance suddenly disappears.
Photo courtesy of superconductors.org
When
this happens, the superconductor actually
undergoes a phase transition and assumes a new
state with zero resistance. The new phase
allows electrons to pair and move down the
lattice freely. This is what makes
superconductors so special.
Bibliography
Main Page
Types of Superconductors