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

12:04pm, May 11, 2005

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.

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