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Published online: 1 February 2012 | doi:10.1038/nchina.2012.13

Molecular physics: A new twist on oxygen

Felix Cheung

Introduction

© (2011) PNAS

Oxygen is the third most abundant element in the universe and the most abundant element in the Earth's crust. At room temperature, oxygen becomes a solid at pressures greater than 9 GPa. A better understanding of the physics and chemistry of solid oxygen could provide important insights into condensed matter and the evolution of planets.

Yanming Ma at Jilin University in Changchun and Hokwang Mao at the Carnegie Institution of Washington in the USA and co-workers¹ have now used their CALYPSO (crystal structure analysis by particle-swarm optimization) algorithm to simulate the structure and physical properties of oxygen at pressures of up to 2 TPa. Their simulation predicts that further increasing the pressure to 1.92 TPa would cause the molecules in solid oxygen to dissociate into tetraoxygen chains (pictured).

Previous studies have shown that solid oxygen is an insulator at pressures of 9–96 GPa and metallic at pressures greater than 96 GPa. The simulation suggests that solid oxygen may become a polymer at pressures greater than 1.92 TPa. The finding is novel because it goes against the conventional belief that materials always become metallic at high pressures.

The authors of this work are from:
State Key Laboratory of Superhard Materials, Jilin University, Changchun, China; Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC, USA; Beijing Computational Science Research Center, Beijing, China.

Reference

1. Zhu, L. et al. Spiral chain O₄ form of dense oxygen. Proc. Natl Acad. Soc. 109, 751–753 (2011). | Article | OpenURL | | ChemPort |