Crystal field and EPR studies of Nd3+:YMO4 (M = V, As, P)

Crystal field calculation and electron paramagnetic resonance (EPR) have been performed on zircon-type materials Nd:YMO4 (M=V, As, P). Simulation of the energy level schemes has been carried out and the wave functions composition and g tensor principal values associated to the first sub-level of the I-4(9/2) manifold were calculated. A rather good correlation is obtained between crystal field calculations and the EPR measurements. Furthermore, some extra lines observed by optical spectroscopy (absorption and emission) also appear on the EPR spectra and a correlation between the two spectroscopies indicates that Nd3+-Nd3+ exchange and dipolar interactions occur in the zircon family, even at very low doping content (less than 8X10(19) Nd3+ ions cm(-3)). Nd3+-Nd3+ pairs at distances 3.9, 5.9 and 6.3 Angstrom have been identified. (C) 1998 Elsevier Science S.A.