Structural modifications induced by electron irradiation in SiO2 glass: Local densification measurements

摘要

We report a study on the structural modi. cations induced in amorphous silicon dioxide (a-SiO2) by electron irradiation in the dose range from 1.2.10(3) to 5.10(6) kGy. This study has been performed by investigating the properties of the Si-29 hyperfine structure of the E-gamma ' center by electron paramagnetic resonance (EPR) spectroscopy. Our data suggest that the structural modi. cations induced by irradiation take place through the nucleation of confined high-defective and densified regions statistically dispersed into the whole volume of the material. In addition, we have estimated that in the high dose limit (D >= 10(5) kGy) the degree of densification associated to the local (within the defective regions) polyamorphic transition follows a characteristic power law dependence on the dose given by bD(nu), where b =(2.0 +/- 0.3).10(-3), nu = 0.160+/-0.004 and D is the irradiation dose measured in kGy.