A crush on nitrogen

Nitrogen gets the squeeze (from Nature)

One of the more mundane seeming elements, nitrogen, can, when pressurized, form a semiconductor material. So say researchers at the Carnegie Institution of Washington writing in a short communication in Nature.

Applying a pressure of up to 2.4 million atmospheres to nitrogen converts the everyday gas into an opaque, semiconducting solid that remains stable even when the pressure is released; at low enough temperatures. "The fact that the major portion of the air has been turned into a semiconducting solid and brought back to be stable at ambient pressure is an important breakthrough for us," says team leader Russell Hemley. The team's electrical measurements on a condensed gas under such extreme high-pressure conditions are the first recorded and reveal that the new, dense form of nitrogen stores a large amount of energy and, says Hemley, could account for part of the core of large gas planets such as Jupiter and Saturn.

	Could this gassy giant have a semiconducting nitrogen heart?

Years ago, theorists had predicted that molecular nitrogen would become either a semiconductor or a metal at 1 million atmospheres or more and a similar theory holds for gaseous hydrogen. But, experimentalists were limited by the amount of pressure they could apply and in the tests they could do under these conditions. Hemley's present work provides the first confirmation of the predictions.

Reference:
Nature, 2001, 411, 170-174