Types of Superconductors

According to the properties and methods which the metal or element undergo, the superconductors are classified into two types.

• Type-1 superconductors and
• Type-2 superconductors

Type-1 superconductors:

• Type-1 superconductors are called as "soft" superconductors, since they require very low temperatures to exhibit superconductive property.
• They show normal conducting state at room temperatures, and posses "perfect" diamagnetism to repel the magnetic field completely.
• However Type-1 superconductors can repel weak magnetic field , in other words weak magnetic field cannot penetrate through these superconductors.
• But when the applied magnetic field rises above the critical value Hc.
• This type of superconductivity is seen in pure metals such as aluminium,mercury and lead etc.,
• The only alloy which is known up to now which exhibits type-1 superconductivity is TaSi2 (Tantalum silicide)

Type-2 superconductors:

• Type-2 superconductors are also known as high temperature superconductors.
• They posses flux pinning property which type-1 superconductors cannot since they repel magnetic field.
• Flux pinning: In the vortex state , the superconductor is pinned in a space above the magnet, which is a friction less state.
• Type-2 superconductors are mostly seen in metal alloys or complex oxide ceramics.

Super conductors - basic info

How it was invented...

• James Dewar is the one who initiated the research of testing the properties of conductors at very low temperatures.
• John Ambrose predicted that the super conductors may achieve infinite conductance and zero resistance, but then came the third law of thermodynamics stating no conductor can achieve absolute zero resistance.
• i.e.,even a ideal conductor too has some resistance, but it is negligible.
• Achieving low temperatures were challenging that time.
• After some years linde's machine was successful to achieve liquefying helium and nitrogen.
• when conductors are dipped into the presence of super cooled liquids, they acquire super conducting state.
• 

These are the basic information of invention of super conductors , in next post we can discuss about the series of experiments conducted on them to find the best super conducting material we've got