Color tunable and thermally stable luminescence of Tb3+ doped Li4SrCa(SiO4)2 phosphors

► Lowest spin-allowed and spin-forbidden f-d transitions locate at 250 and 280 nm. ► Cross relaxation shortens lifetime of 5D3 level, while that of 5D4 are unaffected. ► Cross-relaxation can explain concentration quenching of the 5D3 emission. ► Dipole-quadrupole interaction is responsible for the non-radiative relaxation. ► Li4SrCa(SiO4)2:Tb3+ is thermally stable and color tunable phosphor.