Synthesis and photoluminescence properties of divalent rare-earth-doped Li<sub>2</sub>CaSiO<sub>4</sub>

As potential candidates for neutron scintillators, divalent rare-earth-doped Li2CaSiO4 (Ln:LCS) phosphors were synthesized and their photoluminescence (PL) properties were evaluated. LCS is as light as LiCaAlF6 and has a low density of 2.86 g/cm3 and a small effective atomic number of 14. In this study, a ferrosilicon powder was used as a safe and convenient reductive medium for the reduction of Ln3+ to Ln2+. Sm, Eu, and, Yb were doped into LCS, where they occupied the Ca2+ sites. Among the phosphors synthesized by embedding in the ferrosilicon powder, Eu:LCS, Yb:LCS, and Eu,Yb:LCS exhibited luminescence arising from 5d–4f electronic transitions of the divalent emitter ion. All three divalent ion-doped phosphors had slower PL decay components with lifetimes of the order of tens of microseconds. Although Ln:LCS appears to be unsuitable for neutron detection under high doses owing to the slow decay of the doped Ln2+ emission, the phosphors, notably Eu2+ phosphors, have relatively high emission intensities and can potentially be applied as high-temperature neutron scintillators.