From UPSC perspective, the following things are important :
Prelims level : Superconductivity
Mains level : Superconductors and their future uses
- About a year ago, two scientists from IISc Bangalore had observed superconductivity at room temperature, in a new composite material made of gold and silver.
- If the claimed discovery is confirmed, it could be one of the biggest breakthroughs in physics in this century so far.
Silver embedded gold matrix
- The material that exhibited superconductivity is in the form of nanosized films and pellets made of silver nanoparticles embedded in a gold matrix.
- Interestingly, silver and gold independently do not exhibit superconductivity.
What is Superconductivity?
- Electricity is essentially the movement of free electrons in a conducting material like copper.
- While the movement of electrons is in one particular direction, it is random and haphazard.
- They frequently collide with one another, and with other particles in the material, thus offering resistance to the flow of current.
- The picture is similar to one of messy traffic in a congested urban area. In the process, a lot of electrical energy is lost as heat. Resistance is a measurable quantity, which varies with the material.
- Superconductivity is a state in which a material shows absolutely zero electrical resistance.
- While resistance is a property that restricts the flow of electricity, superconductivity allows unhindered flow.
- It is a phenomenon that, so far, has been possible only at extremely low temperatures, in the range of 100°C below zero.
A phenomenon of zero resistance
- The search for a material that exhibits superconductivity at room temperature, or at least manageable low temperatures, has been going on for decades, without success.
- In a superconducting state, however, the material offers no resistance at all.
- All the electrons align themselves in a particular direction, and move without any obstruction in a “coherent” manner.
- It is akin to vehicles moving in an orderly fashion on a superhighway.
- Because of zero resistance, superconducting materials can save huge amounts of energy, and be used to make highly efficient electrical appliances.
Why is superconductivity difficult to achieve?
- The problem is that superconductivity, ever since it was first discovered in 1911, has only been observed at very low temperatures, somewhere close to what is called absolute zero (0°K or -273.15°C).
- In recent years, scientists have been able to find superconductive materials at temperatures that are higher than absolute zero.
- But in most cases, these temperatures are still below -100°C and the pressures required are extreme.
- Creating such extreme conditions of temperature and pressure is a difficult task.
- Therefore, the applications of superconducting materials have remained limited as of now.