Investigating the Melt Curve of Sapphire Using Double Shock Compression*

Sapphire is a commonly used window material for dynamic compression experiments [1] and plays a role in solid solution with the (Mg,Fe)SiO3 system in Earth’s lower mantle [2]. Therefore, it is important to understand its equation of state, optical properties, and melt curve.  By using a dynamic precompression platform, we can benchmark the equation of state of sapphire off its principal Hugoniot; namely along the melt curve at pressures nearly two time higher than using a single shock.  We present measurements on the sapphire melt curve above 1 TPa which show signatures of latent heat of melting, and present changes in the reflectivity across phase transitions in the doubly shocked sapphire.

[1] Z.-G. Li et. al., Physical Review B 98, 064101 (2018)

[2] S. Gréaux et. al., Geophysical Research Letters 43, 4239 (2016)