ELECTRON-SPIN-RESONANCE OF V-4+(VO2+) IN BERYL

Synthetic Australian Biron beryl coloured green by vanadium was irradiated with a dose of 10 kGy of Cs-137 gamma rays. The resulting ESR spectrum has been modelled as being due to 12 equivalent VO2+ centres, each arising from a complex formed from the substitution of V3+ in the beryl aluminium octahedral site, together with electron loss and motion towards a nearest neighbour oxygen. Each centre can be fitted to an axial spin Hamiltonian H = beta-H.g.S + I.A.S, with parameters S = 1/2, I = 7/2 and [GRAPHIC] and with the z axis at 64-degrees to the crystal c(0001) axis and at 74-degrees to a crystal a axis.