Elasticity of single-crystalline graphite: Inelastic x-ray scattering study

The five independent elastic moduli of single-crystalline graphite are determined using inelastic x-ray scattering. At room temperature the elastic moduli are, in units of GPa, C₁₁=1109, C₁₂=139, C₁₃=0, C₃₃=38.7, and C₄₄=4.95. Our experimental results are compared with predictions of ab initio calculations and previously reported incomplete and contradictory data sets. We obtain an upper limit of 1.10.3em0exTPa for the on-axis Young's modulus of homogeneous carbon nanotube, thus providing important constraints for further theoretical advances and quantitative input to model elasticity in graphite nanotubes.