You all are familiar with the conductor, insulator, or semiconductor. But today we talk about superconductors.
The resistivity of metals decreases with a decrease in temperature and vice-versa. But for some metals and chemical compounds, their resistivity abruptly decreases to zero when they cooled down to absolute zero temperature (0°K or -273°C).
On 8 April 1911 a dutch physicist Heike Kamerling Onnes discovered superconductivity when he observed that at the temperature of approximately 4K (-290 °C), the resistance in mercury abruptly disappeared. For the discovery of superconductivity, the dutch physicist was awarded the Nobel prize in physics in 1913.
Later in 1933 Walter Meissner and Robert Ochsenfeld discovered the Meissner effect.
What is a superconductor?
In simple terms, they are substance that possesses superconductivity.
So what’s this superconductivity?
It is the phenomenon observed in certain materials where some metal and chemical compounds whose resistivity becomes zero when they are cooled below their transition temperature.
Therefore, superconductors are those substances that conduct electricity without any resistance when it becomes colder than its transition temperature. For eg. Mercury becomes superconducting when it is cooled at 4.5K (-268°C).
It is to be noted that the transition from conducting state to a superconduction state is sudden. The temperature at which the transition happens of material from conducting state to a superconducting state is called transition temperature.
It is seen during an experiment that the current is induced in the mercury when it is cooled down at 4.5K, the current will continue to flow for years without consuming any power from the supply. Similarly for many other substances.
When a magnetic field is applied to the superconductor it doesn’t penetrate into the body, this effect is called the Meissner effect. But when a strong magnetic field (beyond a critical value) is applied to it the superconductivity of the substance restores back to the normal conducting state.
Types of superconductor
So talking about the types of superconductors, we got 2 types one is type 1 and another is type2.
It is also known as a soft superconductor. These are generally pure metals. These act as conductors at room temperature but when cooled down below transition temperature it acts as a superconductor.
It is also known as a hard superconductor. They are made up of metal alloys or complex oxide ceramics. It is seen that all high-temperature superconductors are type2 superconductors. These are not good conductors at room temperature.
There are a few applications which are listed below:
- MRI scanner
- It can be used to perform logic and storage functions in the computors.
- Particle accelerators