Elasticity of molecular fullerite C-60 under pressure

Here we present the ultrasonic study of elastic properties of the molecular fullerite C-60 in the temperature range 80-300K at pressures up to 1.4GPa. We have determined for the first time the pressure dependencies of shear modulus and Poisson's ratio. Particularly, the Poisson's ratio was found to increase from approximate to 0.3 at ambient pressures to approximate to 0.38 at p = 1GPa. The observed high values of the Poisson's ratio, as well as high values of the pressure derivatives of bulk modulus approximate to 23-25, are discussed in terms of the central m-n power potential and contribution of the noncentral intermolecular forces.