A novel La₂SrGa₄Si₂O₁₄:Sm³⁺ phosphor for WLEDs and temperature sensing

The development of high-efficiency and thermally stable phosphors is crucial for improving the color rendering index (CRI) of near-ultraviolet (n-UV) pumped white light-emitting diodes (WLEDs). In this work, a novel orange-red emitting phosphor La₂SrGa₄Si₂O₁₄:Sm³⁺ was successfully synthesized via a [Sr²⁺-Si⁴⁺] co-substitution strategy to optimize the lattice of the traditional La₃Ga₅SiO₁₄. Detailed structural analyses confirmed the successful substitution and phase purity. Excited by n-UV light at 402 nm, the phosphor exhibited a prominent emission peak at 600 nm, with an optimal doping concentration of 3 mol%. The material exhibits acceptable thermal stability, retaining 74% of its initial emission intensity at 423 K, together with an internal quantum efficiency of 32.3%, which is comparable to those of several reported Sm³⁺-activated silicate phosphors. When integrated into WLED devices with blue and green phosphors, it yielded high-quality warm white light with a low correlated color temperature of 4680 K and an exceptionally high CRI of 93.2, which represents a noticeable improvement compared with a commercial blue-chip + YAG:Ce WLED measured under identical experimental conditions. Furthermore, by utilizing the unique thermal response characteristics of Sm³⁺ transitions, this material was explored for optical temperature sensing, achieving a maximum relative sensitivity of 2.06% K^-1. These results indicate that La₂SrGa₄Si₂O₁₄:Sm³⁺ is a potential multifunctional material for high-CRI solid-state lighting and non-contact temperature sensing.