Affiliations: Laboratoire d'Etude des Interfaces et des Biofilms en Odontologie (EA 637), Faculté d'Odontologie, Rue Guillaume Paradin, 69372 Lyon cedex 08, France | Departement de Physique des Matériaux (UMR CNRS 5586), Université Claude Bernard de Lyon, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex, France | UMR CNRS 5621 Ingénierie et Fonctionnalisation des surfaces, Ecole Centrale de Lyon, BP 163, 69131 Ecully cedex, France
Note: [] Corresponding author.
Abstract: The influence of sterilization by gamma rays on the structure and the electrical behaviour of sapphire single crystal (α‐Al2O3) was studied successively by thermoluminescence, by cathodoluminescence and by observation of the scanning electron microscope mirror effect. The mirror method allowed us to measure the capacity of an insulating material to trap electrons. The structural analysis of the α‐Al2O3 showed that there were oxygen vacancies, as well as chromium and titanium impurities. It was possible to demonstrate that these defects, especially the oxygen vacancies, are in a different state after a 30 kilogray irradiation. The valency state changes of these defects and the presence of trapped charges are accompanied by a deformation of the crystalline lattice which results in a modification of its electrical properties. At room temperature, the irradiated α‐Al2O3, unlike non irradiated α‐Al2O3, is capable of trapping electrons. It can be concluded that gamma‐ray sterilization modifies the cohesive energy of α‐Al2O3, which could lead to mechanical changes (surface charge, friction, wear, fracture strength, …) in this material.
