Who knew that the gas that stank like rotten eggs in the general chemistry lab could act as a superconductor? Scientists have recently unearthed the physics-defying powers of the smelly hydrogen sulfide.
What is a superconductor?
A superconductor is a material that offers zero resistance to the flow of electric current and expels magnetic fields when cooled below a critical temperature. Discovered by the Dutch physicist, Heike Kamerlingh Onnes, in 1911, superconductivity has revolutionized the world of electronics ever since. Superconductors show infinite conductivity and magnetic levitation properties when they transition into a different state at cooler temperatures. Any metal conductor shows decreased resistance to the flow of electric current at lower temperatures; this gradual decrease is limited to the impurities and defects in the metal itself. Therefore, even at absolute zero (459 degrees below zero), usual conductors show some resistivity. However, superconductors show a drastic drop in resistivity down to zero upon cooling below a certain temperature. This temperature is called the critical temperature and varies from one conductor to another. Mercury was first discovered to show superconductivity at 4.2 K (450 degrees below zero). These numbers demonstrate one of the greatest problems using a superconductors⎯it takes incredibly low temperatures and high amounts of energy to make them behave as superconductors. Even the materials that have relatively high transition temperatures ⎯such as some ceramic cuprates that were found to superconduct at 164 K (164 degrees below zero)⎯are rare and expensive.
The superconducting properties of hydrogen sulfide
In an attempt to uncover superconductive properties of materials, the researchers of the study chose to focus on hydrogen-dominated materials that could easily be converted into metals under really high pressures. Using high pressures, they wanted to achieve the effect of impractically low temperatures at plausible temperature ranges. After testing many materials, they finally had success with hydrogen sulfide. They subjected minuscule amounts of hydrogen sulfide between diamond cells to a pressure that was million times that of atmospheric pressure. Hydrogen sulfide showed superconductivity at just 203 K (94 degrees below zero), which is roughly the temperature of Antarctica.
Applications of a superconductor
While the immediate applications of this new discovery seem distant, other superconductors are being heavily used in the field of electronics. Superconducting electromagnets are extremely powerful and form components MRI, nuclear magnetic resonance (NMR) and mass spectrometers. Superconductors also form the basis for magnetic levitation devices (maglev trains) and magnetic refrigeration.