M. I. Eremets, I. A. Trojan, “Evidence of maximum in the melting curve of hydrogen at megabar pressures”, Pis'ma v Zh. Èksper. Teoret. Fiz., 2009, Volume 89, Issue 4,Pages <nobr>198

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CONDENSED MATTER

Evidence of maximum in the melting curve of hydrogen at megabar pressures

M. I. Eremets^a, I. A. Trojan^ba

^a Max Planck Institute for Chemistry
^b Institute of Cristallography RAS

Abstract: Hydrogen at high pressures of $\sim\,400\,$GPa might be in a zero-temperature liquid ground state (N. Ashcroft, J. Phys. Condens. Matter {A \bf12}, 129 (2000), E. G. Brovman et al., Sov. Phys. JETP 35, 783 (1972)). If metallic hydrogen is liquid, the melting $T_{\rm melt}$(P) line should possess a maximum. Here we report on the experimental evaluation of the melting curve of hydrogen in the megabar pressure range. The melting curve of hydrogen has been shown to reach a maximum with $T_{\rm melt}=1050\pm60\,$K at $P=106\,$GPa and the melting temperature of hydrogen decreases at higher pressures so that $T_{\rm melt}=880\pm50\,$K at $P=146\,$GPa. The data were acquired with the aid of a laser heating technique where diamond anvils were not deteriorated by the hot hydrogen. Our experimental observations are in agreement with the theoretical prediction of unusual behavior of the melted hydrogen [S. Bonev et al., Nature 431, 669 (2004)].

PACS: 62.50.-p, 64.70.dj, 67.63.Cd, 67.80.ff

Received: 18.12.2008

Language: English