Hugoniot measurements for ammonia borane (BH3NH3) and the behavior of metallic hydrogen in the shocked mixture

Understanding the behavior of hydrogen in mixtures under extreme conditions is essential in various science areas. We performed laser-shock compression experiments on ammonia borane (BH3NH3) and measured the Hugoniot equation-of-state up to 365 GPa at the Institute of Laser Engineering, the University of Osaka. From the reflectivity behavior of shocked and re-shocked BH3NH3, metallic hydrogen in the mixture could become immiscible below 120 GPa and 9000 K conditions. We also discuss the microscopic detail of the immiscible/miscible metallic hydrogen based on ultrafast X-ray diffraction observations and ab initio molecular dynamics (AIMD) simulations.