Europium diffusion enhancement in LiNbO3 irradiated with GeV nickel ions: influence of the damage morphology

Abstract

The influence of the damage induced by GeV nickel ion irradiations on europium diffusion in LiNbO3 single crystals was investigated. For this purpose, 10.8 MeV/u 58Ni ion irradiations were performed at room temperature in LiNbO3 samples at fluences in the range 2.0 × 1011–1.2 × 1012ions cm−2. The damage resulting from these irradiations depends on both the electronic stopping power (dE/dx)e and the velocity of the incident ions. Two kinds of damage morphology have been evidenced: (i) amorphous continuous tracks for (dE/dx)e > 10keV nm−1; (ii) discontinuous tracks or isolated defec for (dE/dx)e < 10keV nm−1. After irradiation the samples were implanted with 5.0 × 1016Eu cm−2 at 70 keV and then annealed in air in the range 700–1100°C. Transmission electron microscopy observations exhibit both the continuous tracks and the extended defects induced by the high energy irradiations. Rutherford backscattering spectrometry results show that below or above the threshold of 10 keV nm−1 the enhancement of europium diffusion in LiNbO3 seems to depend, mainly, on the damaged volume.