The Preparation of orange-red Luminescence ZnLa4(SiO4)3O: Sm3+ Phosphors with High Thermal Stability and their Application in LEDs.

A series of orange-red ZnLa₄(SiO₄)₃O:xSm³⁺ (ZLSO:xSm³⁺) (x = 0.2, 0.5, 1, 2, 5, 10, 20, 30, and 35 mol%) phosphors were synthesized via high-temperature solid-state reaction. In this experiment, the lattice environment, phase purity, element distribution, photoluminescence (PL) spectra, thermal stability at different temperatures, and color purity of the ZLSO: Sm³⁺ phosphors were characterized. High-resolution transmission electron microscopy confirms the high crystallinity of the sample. When stimulated at the ideal wavelength of 403 nm, the ZLSO: Sm³⁺ phosphors displayed four significant emission peaks located at 562 nm, 599 nm, 648 nm, and 711 nm. The phosphor's emission intensity was maximized when the Sm³⁺ doping concentration was 2 mol%. Additionally, at 420 K, the ZLSO: Sm³⁺ phosphor retained 86% of its initial emission intensity. The phosphor's internal quantum efficiency (IQE) was determined to be 45.3%. During the experiments, it was found that the color purity of phosphors varied with Sm³⁺ doping levels, but in all cases, it exceeded 98%. Additionally, white light-emitting diodes (w-LEDs) and red LEDs were effectively created by utilizing a 403 nm near-ultraviolet (n-UV) chip in conjunction with the prepared phosphors. The CIE (Commission International de l'Eclairage) coordinates of the obtained w-LED were (0.337, 0.334), with a color rendering index (CRI, R_a) reaching 95. The experimental data suggest that the ZLSO: Sm³⁺ orange-red phosphors hold great potential for use in lighting and optoelectronic applications.