Investigations on radiation-induced processes in dielectric materials

Abstract

Features of experimental study and changes of electrical properties of dielectric materials under irradiation are reviewed. The results on radiation-induced conductivity (RIC) in single crystal Al 2O 3 exposed to fast reactor neutrons up to the dose of 4.7 × 10 24 n/m 2 and in single crystal Al 2O 3 and pyrolitic BN exposed to 7 MeV proton irradiation up to a dose of 2 × 10 20 p/m 2 are presented. In both cases, RIC did not exceed 10 −12 S/cm, the initial value of the conductivity being equal to 10 −14 S/cm. Results of calculations and measurements of likely leakage currents are presented. Formation of carbon and hydrocarbon layers on the surface results in the apparent phenomenon of radiation-induced electrical degradation of dielectrics. The defect clustering in dielectrics occurs in cascades and tracks during the thermal spikes. Under the doses of 3.3–3.5 × 10 25 n/m 2 dielectric breakdown strength of Al 2O 3 is two times as small, and the mechanical strength is 35.5% higher than initial values. The radiation-induced electrical degradation in metal-dielectric systems can be significant.