Electron paramagnetic resonance in gamma-ray, electron and neutron flux irradiated sapphire

Sapphire is irradiated by gamma-ray, electron and neutron flux, respectively, where defects are identified by means of electron paramagnetic resonance (EPR) spectroscopy. The position and intensity of EPR signal in different sources irradiated sapphire are compared in this paper. The g-factor value are 1.978, 1.982, and 2.010 after gamma-ray, electron and neutron flux irradiation, respectively. They are attributed to F+ color centers induced by irradiation and the difference is due to the lattice distortion induced by irradiation. It is found that EPR signal in irradiated sapphire is dependent on the irradiation source type and dose. Effect of annealing and magnetic field direction on the EPR signal is also discussed. A weak signal varying with the magnetic field direction is found in neutron irradiated sample.