Electron trapping centres and cross sections in LiNbO3studied by57Co Mössbauer emission spectroscopy

Fast electron trapping processes and aliovalent charge states following the 57 Co(EC) 57 Fe decay are studied in undoped, 5.4 mol% Mg-doped and 0.1 mol% Fe-doped LiNbO 3 in various thermochemical reduction (TCR) states. Static 57 Co Mössbauer emission spectra of congruent Mg:LiNbO 3 recorded at T = 4.2 K in external magnetic field of 4.6 T are presented. Trapping cross section ratios are derived for Fe 3+ Li , Nb 5+ Li and Mg 2+ Li . A method to determine trap concentrations for TCR states of LiNbO 3 is outlined. The electron-capture distance of the traps is found to be 2.7±1.4 nm. As this is much smaller than the 6 keV Auger-electron penetration depth, it is concluded that the distribution of the aliovalent charge states at 4.2 K is determined mainly by the 600 eV Auger electrons.