Lithium Tetraborate as a Neutron Scintillation Detector: A Review

The electronic structure and translucent nature of lithium tetraborate (Li2B4O7) render it promising as a scintillator medium for neutron detection applications. The inherently large neutron capture cross-section due to 10B and 6Li isotopes and the ease with which Li2B4O7 can be enriched with these isotopes, combined with the facile inclusion of rare earth dopants (occupying the Li+ sites), are expected to improve the luminescent properties, as well as the neutron detection efficiency, of Li2B4O7. The electronic structure of both doped and undoped Li2B4O7 were explored, using photoemission and inverse photoemission spectroscopies, optical measurements, and theoretical computational studies such as density functional theory. The scintillation properties are further enhanced because of the wide bandgap, making Li2B4O7 extremely translucent, so that capturing the neutron scintillation output is neither hindered nor diminished. Therefore, in this review, demonstrations of the possible amplification of neutron capture efficiencies, courtesy of rare-earth dopants, along with insights into a significantly large charge production (associated with neutron capture), are presented.