High-performance luminescence of europium ion-activated Na2O-CaO-SiO2 system glass-ceramics through component regulation and crystallization process optimization strategies

Luminescent glass-ceramics has garnered significant attention within the research community owing to its exceptional characteristics, including robust chemical stability, outstanding thermal stability, and efficient thermal conductivity. However, persistent challenges include issues related to suboptimal luminous efficiency and color rendering index. In the context of this research endeavor, we have achieved a noteworthy achievement by successfully fabricating a novel variant of glass-ceramics doped with both Eu2+ and Eu3+ ions within the Na2O-CaO-SiO2 system glass. This innovative glass-ceramics composition encompassed Na4Ca4Si6O18 crystals, characterized by grain sizes <110 nm. Our investigations, featuring comprehensive optical spectra analysis and detailed morphological examinations, have provided substantial evidence indicating the preferential occupation of Eu3+ ions in the Ca2+ sites residing within the Na4Ca4Si6O18 crystal lattice, conversely, it is possible that the distribution of Eu2+ ions occurred within the glass matrix. Additionally, it is worth noting that this glass-ceramic material demonstrated a heightened excitation efficiency when subjected to 464 nm blue light, surpassing its performance with 393 nm violet light. Detailed fluorescence spectral analysis unveiled the impressive internal quantum efficiency of the glass-ceramics, reaching an impressive 80.27%, and this glass-ceramics exhibited remarkable fluorescence thermal stability at 150 °C, preserving approximately ~75% of its luminescent intensity at room temperature. Furthermore, we have encapsulated the white light-emitting diode (W-LED) device, integrated with a 460 nm LED chip, optimized glass-ceramics, and YAG: Ce3+ phosphor. The outcomes were characterized by the warm white-light emission, suitable chromaticity coordinates, a high color rendering index (approximately 85.4), and impressive luminous efficiency (up to 112.47 lm/W). In summary, these findings unequivocally underscore the substantial potential of glass-ceramics in the realm of high-power W-LED lighting applications.