  Boron-doped diamond undergoes an insulator-metal transition at some critical
value (around 2.21 at %) of the dopand concentration. Here, we report a simple
method for the calculation of its bulk modulus, based on the thermodynamical
model, by Varotsos and Alexopoulos, that has been originally suggested for the
interconnection between the defect formation parameters in solids and bulk
properties. The results obtained at the doping level of 2.6 at %, which was
later improved at the level 0.5 at %, are in agreement with the experimental
values.
