EPR studies of Fe 3+ in Mg-doped LiNbO 3 crystals

Abstract

The X-band electron paramagnetic resonance of eight LiNbO 3: Fe crystals with different Mg doping levels and Li Nb ratios was studied at room temperature. The EPR spectra obtained fall into two classes with quite different spin-Hamiltonian parameters. The critical Mg content which distinguishes the two classes decreases (increases) with increasing (decreasing) Li Nb ratio. The sites occupied by the Fe ions in the two classes of crystals are postulated to be different. The spin-Hamiltonian parameters of Fe 3+ in Li-rich LiNbO 3: Mg(5 mol%): Fe(0.05 wt%) crystals were found to be: g | = 2.025, g ⊥ = 1.910, B 0 2 = 0.266 × 10 −1 cm −1, B 0 4 = 0.551 × 10 −5 cm −1, B 3 4 = 0.326 × 10 −3 cm −1, and those in LiNbO 3: g | = 1.971, g ⊥ = 1.940, B 0 2 = 0.546 × 10 −1 cm −1, B 0 4 = 0.290 × 10 −4 cm −1, B 3 4 = 0.1