It was noted that a surprisingly large number of paramagnetic hole centres in zircon could be observed and characterized by electron paramagnetic resonance. A model was proposed which was based upon some 10 precisely measured centres. The electron paramagnetic resonance data suggested that the trapped hole, produced by X-irradiation, was normally located in the non-bonding pz-orbital of an O- ion and was stabilized by a nearby impurity cation. This was often, but not always, a 3+ ion. Two previously unobserved oxygenic-hole centres were reported here. In one of these, the stabilizing ion was deduced - from the observed 89Y superhyperfine structure - to be Y3+, and it conformed to the above model. The second of them had the most anisotropic g-values yet seen for an oxygenic-hole centre in zircon. Two g-values were significantly below the free-electron value, and a px ground state was implicated.

Oxygenic-Hole Centres in X-Irradiated Zircon: 10K EPR Studies. R.F.C.Claridge, N.S.Lees, W.C.Tennant, C.J.Walsby: Journal of Physics - Condensed Matter, 2000, 12[7], 1431-40