Spectroscopy and Luminescence Dynamics of Ce³⁺ and Sm³⁺ in LiYSiO₄

Abstract

The lithium yttrium silicate series of LiY1–xLnxSiO4 exhibits superb chemical and optical properties, and with Ln = Ce3+, Sm3+, its spectroscopic characteristics and luminescence dynamics are investigated in the present work. Energy transfer and nonradiative relaxation dramatically influence the Ln3+ luminescence spectra and decay dynamics, especially in the Ce3+–Sm3+ codoped phosphors. It is shown that thermal-quenching of the blue Ce3+ luminescence is primarily due to thermal ionization in the 5d excited states rather than multiphonon relaxation, whereas cross-relaxation arising from electric dipole–dipole interaction between adjacent Sm3+ ions is the leading mechanism that quenches the red Sm3+ luminescence. In the codoped systems, Ce3+–Sm3+ energy transfer in competing with the thermal quenching enhance the emission from Sm3+. The combined influences of concentration quenching, thermal ionization, and energy transfer including cross-relaxation on the luminescence intensity of single-center and codoped phosphors are analyzed based on the theories of ion–ion and ion–lattice interactions.