ZIRCON EPR REVISITED - 10-K EPR OF 3 LOW-SYMMETRY CENTERS IN IRRADIATED ZIRCON (ZIRCON SILICATE)

8.9 GHz 10 K EPR studies of three low-symmetry centres in x-irradiated zircon are reported. Precise spin-Hamiltonian parameters are given for a Zr3+ centre, including Zr-91 hyperfine and Y-89 superhyperfine matrices, where the ideal tetragonal symmetry of the Zr site is lowered by charge compensator(s) to Laue class 1BAR. Precise g-values are given for two previously unreported electron-hole centres shown to be located respectively at short- and long-bonded O-ligand sites, each of Laue class 2/m, monoclinic.