Determination of lattice site locations of erbium ions implanted into LiNbO3 single crystals after annealing at moderate and high temperature

X-ray absorption spectroscopy (XAS) has been applied to study the local structure around erbium ions implanted at 300 keV (2×1016 Er+ ions/cm2) in LiNbO3 Y-cut single crystals annealed for 20 h in air at 500 and 1100 °C, respectively. For both samples, the data clearly reveal that Er3+ has neither formed metallic aggregates in the matrix nor precipitated in the form of the oxide. The data for the sample annealed at 500 °C for 20 h show that Er3+ is probably incorporated at the Nb site of the reconstructed LiNbO3 host lattice, or more precisely surrounded by a similar local atomic arrangement. For the sample annealed at 1100 °C for 20 h, the XAS results show that Er3+ is probably located on both Li and Nb sites of the LiNbO3 host, but there remain puzzling points. These can be understood from wide angle X-ray spectroscopy (WAXS) data, which indicate the formation of a phase similar to ErVO3, a perovskite-type compound where the trivalent vanadium is replaced by a mixture of lithium and niobium ions. This result then is in excellent agreement with the ionic radii values of lithium and of niobium ions (0.69 and 0.68 Å, respectively), which are also nearly equal to that of trivalent vanadium (0.68 Å).