Melting of magnesium oxide up to two terapascals using double-shock compression
Linda Hansen, D. E. Fratanduono, Shuai Zhang, D. G. Hicks, Terry‐Ann Suer, Zaire Sprowal, Margaret Huff, X. Gong, B. J. Henderson, D. N. Polsin, Mohamed Zaghoo, S. X. Hu, G. W. Collins, J. R. Rygg
Abstract
Constraining the melting behavior of magnesium oxide, a major constituent of gaseous and rocky planets, is key to benchmarking their evolutionary models. Using a double-shock technique, we extended the MgO melt curve measurements to 2 TPa; this is twice the pressure achieved by previous melting experiments on any material. A temperature plateau is observed between 1218 and 1950 GPa in the second-shock states, which is attributed to latent heat of melting. At 1950 GPa, the measured melting temperature is 17 600 K, which is 17% lower than recent theoretical predictions. The melting curve is steeper than that of ${\mathrm{MgSiO}}_{3}$, indicating that MgO is likely solid in the interior of Saturn-sized gas giants and extra-solar super-Earth planets.