What is Super conductivity?

In 1911, it was discovered by Kammerlingh Qnnis, that at certain temperature range and often within very narrow temperature the electrical resistively of many metals and alloys drops suddenly to zero.

This phenomenon has been given the name superconductivity. He observed that resistance of mercury vanishes suddenly at 4.2k. The materials, which show this property, are called superconductors.

These superconductors are materials, which possess much more than the infinite conductivity. They are perfect electrical conductor with practically no resistance. Research led to the discovery also found that certain alloys become superconductivity at abnormally high temperature.

For example, Nb₃Sn a niobium-tin alloy, is super conductive at 180° Kelvin, when cooled to nquia-neiium temperature, this alloy retains its superconductivity amazingly well. Today, Thalium, Barium, Calcium, Copper oxide, Bismuth etc. are considered most attractive material for super conductors.

Uses and Applications:

In world plagued by energy crisis, the concept of superconductivity has come about as a boon to mankind. The super conductor has many advantages over normal conductors. These are:

(i) In normal conductors, the energy is lost because resistance is given off as heat, which makes the packing of electrical circuits risky. Thus, a superconductor with no resistance and consequently no heat building is found suitable to pack the circuits tightly.

(ii) They save electricity as energy loss due to resistance offered by the conductor is reduced.

(iii) They have ability to generate very powerful fields from relatively small super conducting electromagnets.

(iv) They can create Josephson junction, which are capable of detecting minute magnetic fields and also have the advantage of switching 100 times faster. These magnetic field detectors are super conducting quantum interference devices or SQUIDS.

Due to these inherent advantages, superconductors have been put a variety of uses.

(i) Superconductor electromagnets are used to generate extremely powerful magnetic fields, which are used in atomic colliders.

(ii) Mass drives are used to accelerate the object to very high velocity.

(iii) Superconductor is also used in magneto cardiograms, nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI) etc. These procedures help the medical exports to take detailed images of organs without having to cut open the skin.

(iv) Magnetic Levitated Trains (M.L.T) floats 4 inches above their tracks and hence no friction is involved which could have limited their speed. For eg- “Bullet Trains” move at very high speed upto 500 kph.

(v) It has allowed for design and construction of a new breed of ICS with tremendous capabilities. India’s progress/achievements in super conductivity research:-

Acknowledging the importance of super conductivity, a Programme Management Group was set up by the Government in 1987. It was soon replaced by the National Super-Conductivity Science and Technology Board in 1991. Now various research works is being entrusted to DAE, CSIR, and IITS. The areas of research work included improvement in critical temperature, workability of yitrium, Bismuth, Thalium, SQUIDS etc.

The National Physical Laboratory, New Delhi had developed a SQUID at liquid nitrogen of 77k. They will help in geological prospecting and biomagnetism. Similarly super-conducting magnetic ore separators are being used in places like Kudremukh etc. In a major development Bharat Heavy Electronics Limited, Hyderabad have built and tested the country’s first super conducting generator.

The generator is cooled by liquid helium and has a capacity of generating 200kv amperes. It has succeeded in cutting down an energy loss but the use of liquid Helium is proving very costly and efforts are on to substitute it with relatively cheaper liquid Nitrogen.