Multifunctional evaluation of Dy³ ⁺-doped borate glass: Thermal sensing potential, structural characteristics, and luminescent performance

This study explores the structural, optical, and thermal luminescence properties of dysprosium (Dy 3+ )-doped borate glasses with the composition 75B 2 O 3 -10Li 2 O-(15-x)BaO-xDy 2 O 3 (0.1 ≤ x ≤ 1.0 mol%) synthesized via the melt-quenching technique. The incorporation of Dy 3+ ions led to systematic increases in density, refractive index, and field strength, indicating a densified glass network with enhanced rare-earth–ligand interactions. X-ray diffraction and FTIR spectroscopy confirmed the amorphous nature and the presence of BO 3 and BO 4 structural units. UV–Vis–NIR absorption spectra exhibited sharp intra-4f transitions, while nephelauxetic and bonding parameters (β ≈1.0022; δ ≈ -0.21) suggested slightly ionic Dy-O coordination. Photoluminescence (PL) studies revealed two prominent emission bands at 482 nm and 575 nm corresponding to Dy 3+ transitions. Optimal luminescence was observed at 0.5 mol% Dy 2 O 3 , beyond which concentration quenching occurred via dipole–dipole interactions, confirmed by Dexter’s analysis (Q ≈ 6.6). Differential thermal analysis yielded a glass transition temperature (T g ) of 524 °C and Hruby’s parameter of 1.09, indicating excellent thermal stability. Temperature-dependent photoluminescence (TDPL) and fluorescence intensity ratio (FIR) analyses demonstrated robust thermal sensing behavior, with a quenching temperature (T Q ) of ~ 406 K and moderate activation energy (E a ≈ 0.17 eV). The material retained over 81% of its emission intensity at 423 K, confirming its applicability in thermally stable environments. The chromaticity coordinates (CIE x ≈ 0.366, y ≈ 0.403) lay in the white region, making it a suitable candidate for warm white LEDs. These multifunctional glasses show strong potential for both solid-state lighting and non-contact optical thermometry. • Efficient white-light emission with optimal Dy³⁺ concentration at 0.5 mol% and a dominant yellow transition (⁴F₉/₂ → ⁶H₁₃/₂). • Excellent thermal sensing behavior with T Q ≈ 406 K and activation energy of 0.17 eV. • High thermal and structural stability supported by a glass transition temperature of 524 °C and Hruby’s parameter of 1.09. • Color coordinates near white region (x ≈ 0.366, y ≈ 0.403), making the material suitable for WLEDs. • Dipole–dipole quenching mechanism confirmed by Dexter analysis (Q ≈ 6.6).