Universal diamond edge Raman scale to 0.5 terapascal and implications for the metallization of hydrogen

The recent progress in generating static pressures up to terapascal values opens opportunities for studying novel materials with unusual properties, such as metallization of hydrogen and high-temperature superconductivity. However, an evaluation of pressure above similar to 0.3 terapascal is a challenge. We report a universal high-pressure scale up to similar to 0.5 terapascal, which is based on the shift of the Raman edge of stressed diamond anvils correlated with the equation of state of Au and does not require an additional pressure sensor. According to the new scale, the pressure values are substantially lower by 20% at similar to 0.5 terapascal compared to the extrapolation of the existing scales. We compare the available data of H-2 at the highest static pressures. We show that the onset of the proposed metallization of molecular hydrogen reported by different groups is consistent when corrected with the new scale and can be compared with various theoretical predictions.

Automated summary

The recent progress in generating static pressures up to terapascal values opens opportunities for studying novel materials with unusual properties. We have developed a universal high-pressure scale based on the shift of the Raman edge of stressed diamond anvils correlated with the equation of state of Au. This scale allows for accurate evaluation of pressures up to 0.5 terapascal and has revealed lower pressure values compared to existing scales.