Current affairs 23rd July By Right IAS
New Nature study on superheating gold
What Did Scientists Discover?
Scientists found that gold can stay solid even when heated to 14 times its normal melting point, if it is heated very quickly. This challenges a long-held belief that solids must melt at a certain high temperature due to disorder in their atoms.
Important Concepts 1. Superheating: Normally, solids melt when they reach their melting point. But sometimes, if heated under special conditions, a solid can stay solid even above its melting point. This is called superheating.
Entropy Catastrophe (TEC): In 1988, scientists Hans-Jörg Fecht and William Johnson proposed that a solid can’t be heated more than about 3 times its melting point. If it is, the solid becomes more disordered (has more entropy) than its liquid form. This would break the second law of thermodynamics, which says entropy (disorder) should not decrease in an isolated system. That critical temperature was called the TEC – Temperature of Entropy Catastrophe
What Did the New Study Do?
Researchers from Germany, Italy, the UK, and the US used ultrafast laser pulses to heat very thin gold films (50 nanometres thick). These laser pulses heated the gold in just trillionths of a second, so fast that the atoms couldn’t react or move into a liquid state. Right after heating, X-rays were used to check the arrangement of atoms.
What Did They Find?
The gold stayed solid even at a temperature 14 times higher than its usual melting point. The X-ray patterns showed that the atoms were still arranged in a solid
