Sodium's Anomaly

Description and Advantage

Under extremely high pressure, sodium—an excellent conductor—turns into a transparent insulator.

Micromillimetre-sized samples of sodium were subjected to a pressure of two million atmospheres. The overlapping of sodium atoms forced the outer electrons to go into spaces between the atoms. This led to a collapse of its metallic state while its colour changed from black to red to transparent. This find defies existing knowledge that says under high pressures an element goes metallic. The findings, published in the March 12 issue of Nature, will help understand the properties of highly compressed matter found in stars and giant planets.


Down To Earth, May 2009