1Geophysical
Laboratory, Carnegie Institution
of Washington, 5251 Broad Branch
Road N.W., Washington D.C.
20015, USA
2HPCAT, Carnegie
Institution of Washington,
Advanced Photon Source, Argonne
National Laboratory, 9700 South
Cass Avenue, Argonne, Illinois
60439, USA
High-pressure
high-temperature synchrotron
diffraction measurements reveal a
maximum on the melting
curve of Na in the bcc phase at ~31
GPa and 1000 K and a
steep decrease in melting
temperature in its fcc
phase. The results extend the
melting curve by an order
of magnitude up to 130 GPa. Above
103 GPa, Na crystallizes
in a sequence of phases with complex
structures with unusually
low melting temperatures, reaching
300 K at 118 GPa, and an increased
melting temperature is
observed with further increases in
pressure.
