Self-reducing induced Eu2+/Eu3+ dual-emitting glasses for anti-counterfeiting and optical thermometry

Eu ³⁺/Eu ²⁺ co-doped glasses possess extensive application potential in diverse fields, including light-emitting diodes and sensors, due to their distinctive luminescent characteristics. To date, numerous strategies have been devised to facilitate the coexistence of Eu ³⁺ and Eu ²⁺ in materials. Among them, adjusting the composition of the glass matrix stands out as a straightforward and reproducible approach. Herein, a series of Eu ²⁺/Eu ³⁺ co-doped borosilicate aluminate glasses were successfully synthesized via a high-temperature melting method. By elevating the ratios of B ₂O ₃/MgO and Al ₂O ₃/BaO in the matrix, a remarkable self-reduction of Eu ³⁺ in ambient air was achieved because of the structural weakness and lower optical basicity for the designed glass matrix. The reduction of Eu ³⁺ is also related to the formation of E u Z n • and V Ζ n ′ ′ defects. Furthermore, by fine-tuning the melting duration and Eu content, we achieved comparable violet and red emission intensities for both Eu ²⁺ and Eu ³⁺ ions. Under UV irradiation with various wavelengths, anti-counterfeiting patterns fabricated from glass powder exhibited precise and pronounced color changes. Notably, the emission intensity ratio of Eu ²⁺/Eu ³⁺ exhibited a consistent decrease as temperature increased, enabling precise temperature determination with exceptional absolute sensitivity (1.22 % K ⁻¹) producibility, and discrimination. These findings hold significant implications for the design of Eu ³⁺/Eu ²⁺ co-doped inorganic multifunctional glasses.