LAUSR

Abstract The Dy3+ or/and Sm3+ doped LiLa(WO4)2 phosphors are synthesized by a facile solid state reaction method. The phase and luminescence properties of the phosphors are investigated. The powder X-ray diffraction (XRD) results show that the phosphor has a tetragonal phase crystal structure. The quenching concentration of single doped Dy3+ and Sm3+ in the LiLa(WO4)2 are determined to be 6% and 3%, respectively. Under the excitation of 404 nm, warm white light is obtained in the co-doped phosphors. With the concentration of Sm3+ increasing, the correlated color temperature (CCT) gradually decreases from 3090 to 2453 K. Two kinds of energy transfer may exist at the same time. The overlap between the emission spectrum of Dy3+ and the excitation spectrum of Sm3+ reveals that the energy of Dy3+ can transfer to Sm3+ via radiation. Another way of energy transfer, that is non-radiative energy transfer, is attributed to the excited state of Dy3+ (4F9/2) slightly higher than that of Sm3+ (4I19/2). The calculation results show that non-radiative energy transfer process from Dy3+ to Sm3+ ions is predominated by quadrupole–quadrupole interaction.