Li2MnCl4 single crystal: a new candidate for a red-emitting neutron scintillator†

Abstract

A novel red-emitting scintillator Li₂MnCl₄ is proposed as a candidate for thermal neutron detection. It features high Li content, low density, a low effective atomic number, and emission in the red-NIR region. These characteristics make it an interesting candidate for long-distance neutron detection in harsh environments e.g. decommissioning of nuclear power plants. The absorption is thoroughly investigated in the scope of the Tanabe–Sugano diagram. The luminescence mechanism in undoped Li₂MnCl₄ is studied in depth using steady-state and time-resolved photoluminescence. Doping with Eu²⁺ and Ce³⁺ is introduced as a trial to improve the scintillation efficiency. We show that in the Eu²⁺ and Ce³⁺ doped Li₂MnCl₄ the luminescence mechanism involves energy transfer from the dopants to Mn²⁺, and propose the local lattice distortion around the dopant and possible charge compensation mechanisms.