Photoacoustically Measured Speeds of Sound of Liquid HBO₂: Semi-Empirical Modeling of Boron-Containing Explosives

Elucidation of geodynamic, geochemical, and shock-induced processes is often limited by challenges to determine accurately molecular fluid equations of state (EOS). High-pressure liquid-state reactions of carbon species underlie physicochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. Here we introduce a versatile photoacoustic technique developed to measure precise adiabatic speeds of sound of high-pressure molecular fluids and fluid mixtures. Metaboric acid, HBO₂ speeds of sound are measured up to 0.5 GPa along the 277 °C isotherm. A polarized Exponential-6 interatomic potential form, parametrized using our data, enables EOS determinations and corresponding semiempirical evaluations of >2000 °C thermodynamic states including energy release from bororganic formulations. Our thermochemical model predictions of boronated hydrocarbon shock Hugoniot states differ from experiment by