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

Abstract

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 Mössbauer 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.

Unveiling the Defect Structure of Lithium Niobate with Nuclear Methods

“…Additional Mössbauer studies addressed the electron trapping in congruent, nearstoichiometric, Mg-doped and Fe-doped LN [210,211]. It was found that the electron trapping effect by Nb-antisite outweighs that attributed to Fe 3+ despite the larger cross section of the latter.…”