The Effect of Pressure on the Electrical Conductivity of Sapphire

The d.c. electrical conductivity of sapphire has been measured as a function of uniaxial pressure and temperature in the respective ranges 0 < P < 10 kbar, 300 < T < 750 °K. The activation energy for electronic conduction was found to decrease linearly with pressure yielding a zero pressure activation energy of 2.38 ± 0.02 eV. The stress coefficient α of the activation energy for electronic conduction was found to be α = 0.24 × 10−3 – 0.32 × 10−6T eV/bar.