5 Mbar generation by using diamond anvil cell with semi-ball-like tip

Advancements in high pressure generation technology through static compression have pioneered new frontiers in high pressure science. While the double-stage diamond anvil cell (ds-DAC) and the toroidal-type DAC (t-DAC) were developed as means to exceed the pressure generation limits of conventional DACs, their ability to generate extreme pressures exceeding Earth's central pressure is not necessarily highly reproducible. Here, we report results from pressure generation experiments using a DAC with a semi-ball-like tip shape (st-DAC). The gradual change in bevel angle provides a gentle pressure gradient at the culet edge and supports the protrusion through an effective confining pressure at the base. The st-DAC achieved pressures exceeding 400 GPa with high reproducibility, even when the pressure difference relative to the periphery reached 250–300 GPa without failure. For a 5 μm culet size, it enabled the generation of up to 500 GPa.