Elasticity, strength, and refractive index of argon at high pressures

High-pressure Brillouin spectroscopy of polycrystalline argon, measured using two scattering angles (180 degrees and 70 degrees), determines the isotropic elastic moduli, shear strength, equation of state, and refractive index of face-centered-cubic argon from 1.3 to 30 GPa at room temperature. The index of refraction n= 1.33-1.67 over this pressure range. An Eulerian finite-strain analysis (Birch-Murnaghan equation of state) yields an isothermal bulk modulus and pressure derivative K(T)= 15.1(+/- 1.1) GPa and K(T)' = 5.4(+/- 0.3) at 2 GPa. The resulting equation of state agrees well with previous x-ray diffraction measurements, illustrating the suitability of high-pressure Brillouin scattering for characterizing the elasticity and strength of polycrystalline materials.