A polymorphic SrGa2O4:Eu2+ red phosphor for warm illumination and operando visualization of H2O2 catalytic reaction

Abstract

The discovery of multifunctional Eu²⁺-activated luminescent materials with tailored structures and optical properties can address the specific demands of various application fields. Herein, polymorphic SrGa₂O₄:Eu²⁺ phosphors exhibiting temperature-induced phase transformation from γ- to β-phase were fabricated. The polymorphic SrGa₂O₄:Eu²⁺ phosphors show tuned luminescence properties as a result of phase transition, i.e., emit red light at 620 nm and 614 nm for γ- and β-phases, respectively, under 450 nm blue light excitation. The emission spectrum of the phosphors exactly covers the red spectral region, which can minimize the efficacy loss caused by low eye sensitivity at long wavelengths. Thus, these phosphors can serve as a promising red emitter for warm illumination with a high color-rendering index (R_a) of 83 and a low color correlated temperature (CCT) of 3889 K. Additionally, by utilizing the red emission intensity of Eu²⁺ as an identification signal, we broaden the application of the red phosphor as a fluorescent probe in operando visualization of catalytic processes. This work presents a novel polymorphic red phosphor and demonstrates tailoring the optical properties of the material by temperature-induced phase transformation and hence enabling multifunctional applications.