Direct observation of shock-induced formation of davemaoite, Ca-perovskite.

Perovskite-structured silicates are key minerals of Earth's lower mantle and have also been identified in shocked meteorites as the (Mg,Fe)SiO3-perovskite phase, bridgmanite. In contrast, CaSiO3-perovskite (davemaoite) has never been found in meteorites and is known only from rare inclusions in deep-mantle diamonds. This contrast highlights a fundamental gap: while natural samples provide indirect evidence for silicate perovskites under shock conditions, laboratory dynamic compression experiments have yet to directly capture perovskite transitions in either MgSiO3 or CaSiO3, likely due to kinetic limitations imposed by nanosecond timescales. Here we present the in situ, atomic-scale observations of CaSiO3-perovskite formation under dynamic compression. Using nanosecond laser-driven shocks and ultrafast X-ray diffraction (XRD) at SACLA, we tracked the transformation of CaSiO3 from low-pressure phases to an amorphous state, and ultimately to davemaoite above ~91(10) GPa, suggesting a disorder-order transformation pathway toward reconstructive crystallization on nanosecond timescales. Upon release, davemaoite undergoes amorphization via a transient low-symmetry phase. These observations provide direct structural evidence for silicate perovskite formation under dynamic loading, resolving a long-standing experimental problem and establishing dynamic compression as an effective route to probe deep-mantle minerals relevant to Earth and Ca-rich exoplanet interiors.