Studies of neutron irradiation damage in CaO:I

Neutron irradiated CaO has an EPR spectrum at 77K with g-values g/sub /// (100)=2.0694, g perpendicular to =2.0021, due to a V - centre which differentiates it from the previously reported values, suggesting a distinction between the V - centres produced in this way from those produced thermally. On examination of the behaviour of this spectrum with increasing temperature it shows the features of motional averaging. At 195K a broad isotropic line g(iso)=2.0475-approximately 1 / 3 (g/sub ///+2g perpendicular to -is observed, confirming that this is indeed an intrinsic V - centre. Further centres have been discovered which are tentatively identified as interstitial O 2 - along (110) axes and a weaker spectrum of similar centres with the axes tilted by about 14.5 degrees from (110) lying the corresponding (001) plane. Discussion is given of the interpretation of these results.