The Equation of State of Al₂O₃: Dynamic Compression in Terapascal and kilo Kelvin Conditions

Sapphire, known for its remarkable incompressibility at ambient conditions, plays a pivotal role in both static and dynamic compression research. Accurately characterizing its equation of state (EoS) is essential for these applications. We present a complete Hugoniot of Al₂O₃ as locus of experimentally assessed, high-precision, pressure, density and temperature states up to 1.4 TPa and 43 kK. The Hugoniot is established using magnetically launched hyper velocity flyers on the Z Accelerator at SNL. Our findings indicate a significant deviation from existing tabular Al₂O₃ EoS models, dictating a comprehensive overhaul. We develop two advanced EoSs for Al₂O₃: the SESAME 97412 model, featuring an extensive phase diagram, with three solid phases and the liquid phase, as well as the updated LEOS 2200m2 model. Accurate experimental determination of extreme pressures and temperatures, paired with sophisticated models, advances the frontier of EoS development beyond 1 terapascal.