Investigations on the electric-dipole allowed 4f25d → 4f3 broadband emission of Nd3+-doped 20Al(PO3)3-80LiF glass for potential VUV scintillator application

Abstract

We report the absorption and emission properties of neodymium (Nd3+)-doped APLF glasses [20Al(PO3)3-80LiF + x NdF3, x = 0.5–2.0 mol%] as potential vacuum ultraviolet (VUV) scintillator materials due to their interconfigurational 4f25d transitions which have not yet been investigated. The Nd3+-doped APLF glasses exhibit absorption and emission peaks from the VUV to the near-infrared (NIR) regions which correspond to the different interconfigurational 4f25d and intraconfigurational 4f3 transitions of Nd3+ ions. Detailed analysis of the absorption and emission spectra reveals that the Nd3+-doped glass has a disordered structure and low symmetry, as expected from amorphous materials. However, the most important feature of these glasses is their electric-dipole allowed 4f25d → 4f3 (4I9/2) broadband emissions, between two configurations of opposite parity, around 187 nm (VUV) whose ~ 5.0 ns decay times are faster than known Nd3+-doped scintillators. At room temperature (RT), the absorption edge located around 192 nm overlaps with this VUV emission indicating that self-absorption primarily limits the emission intensity. This overlap could potentially be minimized by working at low temperatures and doping with higher (>2.0 mol%) concentrations. Despite the presence of self-absorption, the fast emission decay times from the 4f25d excited state make the Nd3+-doped APLF glasses promising new VUV scintillator materials for high-counting-rate fast neutron detection.