Shock-Wave Exploration of the High-Pressure Phases of Carbon by M. D. Knudson, M. P. Desjarlais, and D. H. Dolan Science Volume 322(5909):1822-1825 December 19, 2008 Published by AAAS

Fig. 1. Phase diagram for high–energy density carbon. Phase diagram for high–energy density carbon. Solid gray line, phase boundaries from Correa et al. (12); dot-dashed gray line, diamond-liquid melt curve from Grumbach and Martin (9); dashed gray line, diamond-liquid melt curve from Wang et al. (11); solid blue line, predicted adiabat for Neptune (Uranus similar) (28); solid black line, AIMD Hugoniot from this work. M. D. Knudson et al. Science 2008;322:1822-1825 Published by AAAS

Fig. 2. Diamond P-ρ Hugoniot: (A) previous data and (B) this work. Diamond P-ρ Hugoniot: (A) previous data and (B) this work. Solid line, AIMD Hugoniot from this work; dashed line, AIMD metastable solid (diamond) and liquid Hugoniots from this work; yellow circles, Gekko laser (16); green triangles, LULI laser (17); blue square, Pavlovskii (29); red diamonds, this work. M. D. Knudson et al. Science 2008;322:1822-1825 Published by AAAS

Fig. 3. Coexistence regions and Hugoniot in P-ρ-T space. Coexistence regions and Hugoniot in P-ρ-T space. The Hugoniot (black line) enters the diamond-liquid coexistence region (orange band) from the diamond phase at ∼680 GPa (6.02 g/cm3), reaches the diamond-bc8-liquid triple point at ∼850 GPa, and exits the bc8-liquid coexistence region (pink band) at ∼1040 GPa (7.04 g/cm3). The Hugoniot has two solutions at the proposed triple point: (i) a mixture of diamond and liquid (6.52 g/cm3) and (ii) a mixture of bc8 and liquid (6.62 g/cm3). M. D. Knudson et al. Science 2008;322:1822-1825 Published by AAAS

Fig. 4. (A) Experimental configuration. (A) Experimental configuration. The figure is not drawn to scale. (B) Graphical impedance matching used to obtain P and up in the shocked state. Blue line, chord with slope given by ρ0Us; red line, the copper Hugoniot. The uncertainties in the measured flyer velocity, the copper Hugoniot, and the measured diamond shock velocity are represented in the figure by the width of the lines. M. D. Knudson et al. Science 2008;322:1822-1825 Published by AAAS

Fig. 5. (A) Us-up slopes. (A) Us-up slopes. Solid (dashed) red line, slope (1σ deviation) of the four segment fit of the Us-up experimental data with breakpoints determined by AIMD; solid black line, slope of the AIMD Us-up Hugoniot; dotted vertical lines, breakpoints corresponding to onset and completion of melt; gray region, bound for the location of the proposed triple point. (B) Residual plot of Us with respect to Us in the solid (diamond) phase. Symbols, solid, and dashed black lines are as in Fig. 2. The gray and red lines represent three- and four-segment fits, respectively. Rightmost shaded region, up corresponding to the saturation in reflectivity observed by Bradley et al. (15). (C) Diamond Us-up Hugoniot. Lines and symbols are as in Fig. 2. M. D. Knudson et al. Science 2008;322:1822-1825 Published by AAAS