Tunable luminescence in Eu3+/Sm3+ single-doped LuNbO4 for optical thermometry and anti-counterfeiting

Abstract

Rare-earth (RE) ion-doped luminescent materials have been widely utilized in both scientific research and practical applications. Recently, designing a single matrix with dual-emitting centers and color-tunable properties to expand their applications has become a trend in the development of luminescent materials. Here, a series of Eu³⁺/Sm³⁺ single-doped LuNbO₄ (LNO) phosphors, with characteristic emissions of the host and Eu³⁺/Sm³⁺ activators, are developed. Interestingly, owing to the energy transfer (ET) from the host to activators, the designed phosphors exhibit multi-color emissions and anti-thermal quenching behavior. Based on the different responses of the matrix and Eu³⁺/Sm³⁺ ions to temperature, the maximum relative sensitivity (S_r) values of LNO:0.001Eu³⁺ and LNO:0.005Sm³⁺ samples reach as high as 2.45% K⁻¹ (@350 K) and 2.49% K⁻¹ (@362 K), respectively. Moreover, under 261/365 nm light excitation, discriminable colors and emission-adjustable properties of the phosphors and LNO:0.005Eu³⁺/Sm³⁺ -polydimethylsiloxane (PDMS) films from 303 to 453 K can be realized, demonstrating their huge potential in anti-counterfeiting. The developed LNO:Eu³⁺/Sm³⁺ samples present highly temperature-sensitive characteristics and excellent optical performance, and also show potential for application in luminescence thermometry, information security, anti-counterfeiting and LEDs.