A comparison of defect centres formed in oxides by explosive shocking and high-energy radiation

Abstract

E.s.r. and reflectance spectroscopic techniques have been used to compare point defects present in MgO, ZnO, and SiO₂ both after explosive shocking and after irradiation with high-energy γ-rays, electrons, and neutrons. A high correlation of shocking with irradiation exists in MgO, none in SiO₂, and ZnO occupies an intermediate position.

In MgO, explosive shocking induced ionisation with trapping of electrons at existing defects and produced vacancy defects (F⁺ and F⁺₂) by displacement of lattice ions. In SiO₂ none of these effects were present but there is evidence of contamination with carbon as a result of the explosion. This significant difference in behaviour to shocking is reflected in the different physical properties of these oxides, but could also be brought about by a suitable choice of explosion conditions.