Gold can stay solid even when superheated far beyond its melting point

When gold is heated quickly, it can remain solid at temperatures well above its melting point, as per a new study in Nature.

Superheating is when a solid stays solid at or above its melting point. Most materials can only be superheated in a narrow range beyond that point before melting. Scientists used to believe this range was fixed due to a limit known as the entropy catastrophe.

Entropy is a measure of disorder in a system. Heating a substance increases its entropy. Previously, scientists thought that if a crystal was heated to about three times its melting temperature, it would have to melt because its atoms would become too disordered.

In 1948, chemist Walter Kauzmann discovered that a liquid could have less entropy than a crystal of the same material beyond a specific temperature, known as the Kauzmann paradox. Decades later, Hans-Jörg Fecht and William Johnson found that a solid superheated to around three times its melting point could have more entropy than its liquid form beyond a particular temperature, known as T EC or entropy catastrophe.

The study on gold explores what happens when the metal is rapidly heated. Understanding the limit of heat a solid can absorb without changing phase is crucial for designing materials for extreme environments.

The researchers used powerful laser pulses to heat gold films rapidly. They then used high-resolution inelastic X-ray scattering to determine the gold atoms' temperature. The team found that solid gold superheated to 14 times its melting point remained solid for a short time, challenging core assumptions about material behavior at extreme conditions.

According to the source: The Hindu.