Wavelength-Tunable of Broad Red to Near-Infrared Emission in (Sr,Ba)ScO :Eu Phosphors: Crystal Field Effects and Thermal Stability.

In this work, a series of Eu-activated phosphors, including SrScO:xEu, BaSrScO:0.015Eu (0 ≤ ≤ 1), and BaScO:xEu, were successfully synthesized via a sol-gel method. The SrScO:xEu phosphors exhibited a broad red emission band centered at 609 nm under 430 nm blue-light excitation, with a measured internal quantum yield of 47.94%. Upon partial substitution of Sr by Ba in SrScO:0.015Eu, a pronounced redshift in the emission maximum was observed, extending from 609 to 843 nm and thereby covering the entire visible to near-infrared (NIR) spectral range, corresponding to a total shift of 234 nm. Structural analysis indicates that the emission behavior of Eu is strongly influenced by its coordination environment within [Sr/Ba1O] and [ScO] octahedra, which exhibit low-symmetry fields and induce substantial crystal field splitting (CFS). Thermal quenching behavior was evaluated by monitoring emission intensity at 150 °C, where SrScO:0.015Eu, SrBaScO:0.015Eu, and BaScO:0.015Eu retained 85.8%, 75.1%, and 65.8% of their room-temperature luminescence, respectively. These findings demonstrate excellent thermal stability and tunable red-to-NIR emission, establishing this phosphor family as a promising candidate for next-generation NIR-emitting materials and photonic applications.