ESR study of rare-earth ions with the effective spin of 1/2 in LiNbO3 crystals

Abstract

Rare-earth ions of Nd 3 § and Er 3 § in nearly stoichiometric and MgO-doped LiNbO 3 crystals, respectively, have been investigated by employing an X-band electron spin resonance (ESR) spectrometer. The grown crystal was heated in Li-rich powder at ll00~ in order to make it nearly stoichiometric by the vapor transport equilibrium technique. Due to the fact that the ESR linewidth is much narrower in the stoichiometric crystal than in the congruent LiNbO3, we were able to determine the hyperfine constants of E43Nd and 145Nd at 4 K. By codoping MgO into LiNbO3, a new Er 3 § center has been observed with a different g-tensor. We propose that the new Er 3+ center in Mg-doped LiNbO 3 occupies the niobium site due to the local excessive Mg 2+ ion at the lithium site, whereas Nd 3+ and Er 3+ in congruent crystals reside at the lithium site. The proposal is consistent with the gvalue anisotropy.

EPR and optical studies of LiNbO3:Yb and LiNbO3:Yb, Pr single crystals

“…In LiNbO 3 :Mg, Yb, Dong et al have shown that the Yb 3+ ions may occupy also Nb 5+ sites because of the role of MgO co-doping [18]. Choh et al [19] arrived at similar conclusion for Er 3+ in Er and Mg codoped LN single crystals. Malovichko and Grachev [20,21] have shown that RE ions enter octahedral sites in LN, which may exhibit the C 3 or C 1 site symmetries.…”

The relationship between the g-shift and the local structure for the axial impurity centers in the doped LiNbO3 crystals

“…The Er 3+ paramagnetic centers with axial symmetry in LiNbO 3 single crystals were investigated by many scientists [3,9,13,14]. We are focused on the Er 3+ centers in LiNbO 3 and MgO or ZnO codoped LiNbO 3 crystals because one can compare our results with those obtained by other methods in the case of this crystal.…”

“…Choh et al [9] report SH parameters of new Nd 3+ (and Er 3+ ) centers in lithium niobate single crystal. The EPR g-factor and the local structure for the trigonal Nd 3+ center in LiNbO 3 :Nd single crys- tal are investigated, too [10].…”

Temperature dependence of the EPR spectra and optical measurements of LiNbO3: Er, Tm single crystal

“…the Li/Nb concentration ratio). Properties of RE 3+ centres in LN are directly related to the defects associated with the non-stoichiometric conditions [7].…”

“…Rareearth (RE) dopant ions, as e.g. Nd 3+ or Er 3+ , are introduced to LN host as optically active impurities [7]. The relative concentration of such impurities depends on the stoichiometry (i.e.…”