Tailoring bismuth visible emission via glass composition engineering

We explore the tunability of bismuth ion (Bi 3+ ) emission by modifying the glass composition and structure through the inclusion of specific alkaline (Li + , Na + , K + ) and alkaline earth (Ca 2+ , Ba 2+ ) ions. Bi 3+ -doped oxide glasses were synthesized using the melt-quenching method and extensively analyzed using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and X-ray absorption spectroscopy (XAS). Their optical properties were evaluated through photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy. Our findings show that that the glass transition temperature and network structure exhibit a different evolution when only alkaline ions or both alkaline and alkaline earth ions are included simultaneously. This behaviour is related to the presencen or not of the mixed alkali effect in different glass systems. XAS analysis confirms the presence of Bi 3+ ions. The incorporation of Li + , in combination with Na + and/or K + , leads to broad PL emission spanning from blue to near-white light and extending into the orange-red region under UV excitation. Notably, Li + plays a crucial role in shifting the Bi 3+ emission toward the orange-red spectrum, with Na + and K + further enhancing this shift, likely due to the mixed alkali effect. Meanwhile, glasses containing Ca 2+ and Ba 2+ exhibit tunable cyan-to-white emission, which can be precisely controlled by adjusting their concentrations. This study highlights the critical role of glass composition engineering in optimizing the luminescent properties of Bi 3+ -doped glasses, offering valuable insights for the development of advanced photonic materials.