Two Ti3+ centres studied by X-band electron paramagnetic resonance at 10 K in zircon

Two previously unreported Ti3+ paramagnetic centres have been observed in zircon (zirconium silicate, ZrSiO4) and studied by X-band electron paramagnetic resonance at approximate to 10 K. The first of these is shown to arise from a Ti3+ electron-trap centre where Ti substitutes into one of the Si4+ sites, point group symmetry;(4) over bar 2m (D-2d), of the tetragonal crystal. A full spin-Hamiltonian analysis of the centre is given. The second centre arises from Ti3+ substituting for Zr4+ in the lattice and interacting with a 100% spin-I = 1/2 nucleus, probably P-31, in a nearby lattice site, thought to be a next-nearest-neighbour Si site. The point group symmetry of the site of this centre is 2 (C-2).