Controllable thermochromic luminescence in SrMoO4: Eu/Tb by nonradiative relaxation and local symmetry for anti-counterfeiting and high-temperature sensing applications

Reasonable modulation of temperature-dependent luminescence color has attracted significant attention due to its promising applications in anti-counterfeiting and temperature sensing. Although research on thermochromic materials is growing, the detailed exploration of the causes remain insufficiently explored. In this study, we successfully synthesized SrMoO₄:Tb/Eu samples exhibiting thermal-responsive color tuning. Under 280 nm excitation, the intensity ratio of Eu³⁺(⁵D₀→⁷F₂) to Tb³⁺ (⁵D₄→⁷F₅) in SrMoO₄:0.08Tb/0.12Eu gradually increases from 0.81 to 5.8 over the temperature range of 303K–573K, accompanied by a distinct color shift from red to yellow. Experimental investigations demonstrated that the thermochromic behavior of the sample is primarily governed by nonradiative relaxation rates and local site symmetry. These results indicated that the samples can have potential for anti-counterfeiting and temperature sensing, particularly suitable as temperature sensing in the high-temperature reactor observation window.