Researchers have broken a fundamental limit known as the entropy catastrophe, allowing them to heat solid gold to over 14 times its melting temperature for just a fraction of a second. This achievement has significant implications for our understanding of material properties and could lead to improved production methods.
Entropy is a measure of disorder in a system, with liquids typically having more entropy than solids. However, it’s theoretically possible to supercool liquids or push solids to higher temperatures than their melting points. The entropy catastrophe occurs when the temperature of a solid equals that of its liquid counterpart.
Gold has a high melting point of 1,064°C (1,947°F), but researchers used gold films only 50 nanometers thick and heated them with an X-ray laser for just 45 femtoseconds to reach this record-breaking temperature. The team’s approach bypassed the entropy catastrophe by using extremely rapid heating.
To achieve this feat, the researchers created a brief period of intense energy transfer, causing every atom in the sample to vibrate rapidly. This motion is related to the average kinetic energy of particles, which can be linked to temperature. While the experiment was limited by the short duration and potential measurement challenges, it showcases remarkable advancements in phase transition physics.
The study, published in the journal Nature, holds promise for unlocking new possibilities in material production and control over superheating and melting processes.
Source: https://www.iflscience.com/solid-gold-superheated-to-14-times-its-melting-point-bypassing-the-entropy-catastrophe-80120