Metal Rebel: Under extreme pressure, sodium breaks the rules for turning into liquid

In a demonstration that defies basic assumptions in physics, researchers have created liquid sodium at room temperature.

As a member of the alkali metals—the first column in the periodic table—sodium is considered to be one of the simplest metals. Under normal conditions, it melts at about 98°C, just under water's boiling point. The new observation that sodium can melt at just above room temperature, 27°C, confirms a growing suspicion among scientists that alkali metals are more complicated than they previously thought.

Eugene Gregoryanz of the Carnegie Institution of Washington (D.C.) and his colleagues loaded a microscopic sample of solid sodium into a diamond-anvil cell, a viselike device capable of generating extreme pressure.

The researchers repeatedly raised the pressure inside the cell and determined sodium's melting temperature at each of these pressures by heating the material.

When a solid is squeezed under high pressure, its co