57Co Mössbauer emission spectra of undoped and Fe or Mg melt-doped LiNbO3 single crystals show substantial amounts of the nucleogenic Fe3+ charge state (*Fe3+) which was generated as an after-effect of the electron-capture of 57Co2+. The proportion of *Fe3+ is markedly dependent on the Mg content and on the stoichiometry of the sample. Electron trapping is described within the model of competing acceptors. The capabilities of the model are investigated in defect structure analysis and charge trapping studies of LiNbO3.

Fast electron trapping processes and aliovalent charge states following the 57Co(EC)57Fe decay are studied in undoped, 5.4 mol% Mg-doped and 0.1 mol% Fe-doped LiNbO3 in various thermochemical reduction (TCR) states. Static 57Co Mossbauer emission spectra of congruent Mg:LiNbO3 recorded at T = 4.2 K in external magnetic field of 4.6 T are presented. Trapping cross section ratios are derived for Fe3+Li, Nb5+Li and Mg2+Li. A method to determine trap concentrations for TCR states of LiNbO3 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.

Fast electron trapping processes and aliovalent charge states following the Co-57(EC)Fe-57 decay are studied in undoped, 5.4 mol% Mg-doped and 0.1 mol% Fe-doped LiNbO3 in various thermochemical reduction (TCR) states. Static Co-57 Mossbauer emission spectra of congruent Mg:LiNbO3 recorded at T = 4.2 K in external magnetic field of 4.6 T are presented. Trapping cross section ratios are derived for Fe-Li(3+), Nb-Li(5+) and Mg-Li(2+). A method to determine trap concentrations for TCR states of LiNbO3 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.