Luminescence of LiTb(PO₃)₄:Sm³⁺ and energy transfer from Tb³⁺ to Sm³⁺ under vacuum ultraviolet–ultraviolet excitation

The photoluminescence (PL) of LiTb(PO3)(4), LiGd0.97Sm0.03(PO3)(4), and LiTb0.97Sm0.03(PO3)(4) under vacuum ultraviolet (VUV)/ultraviolet (UV) excitation were studied. We observed the VUV-UV sensitization of Sm3+ emission (561 nm, 601 nm, 649 nm, and 710 nm) by Tb3+ in LiTb(PO3)(4):Sm3+, which leads to the yellow light emission (486 nm, 546 nm, 561 nm, 587 nm, 601 nm, 621 nm, 649 nm, and 710 nm) of LiTb(PO3)(4):Sm3+ phosphor under UV and VUV excitation. The emission is a result of partial energy transfer from Tb3+ to Sm3+, which is discussed in detail in terms of the excitation and emission spectra and decay curves.