Tailoring the structural, photoluminescence, and electrical properties of Ag2O-borotellurite glasses via lanthanum nanoparticles doping for stable cool-white luminescent applications

Abstract

Absrtract A series of La 2 O 3 -doped glasses were methodically developed to examine their structural, electrical, dielectric, and luminescent properties at room temperature. The results from Raman spectroscopy indicate a reorganisation of the network upon the introduction of La 2 O 3 , characterised by the transformation of TeO 4 to TeO 3 (788 → 780 cm −1 ) and the shifts in BO 3 and BO 4 stretching modes. The analysis of real and imaginary parts of impedance (Z′ and Z'') and electric modulus (M′, M'') parameters reveals a bulk behaviour that is highly resistive and demonstrates non-Debye electrical relaxation. The dielectric constant (ε') remains low, with single-digit values up to 10 kHz, confirming the absence of space-charge accumulation. In addition, the AC conductivity (σ AC ) shows dispersion above 100 Hz, indicating localised charge hopping . When subjected to UV excitation, photoluminescence spectroscopy reveals a significant blue peak at 425 nm along with a yellow shoulder at 550 nm. The CIE 1931 coordinates obtained are located within a consistent cool-white and cyan-blue region, illustrating a colour tracking trajectory that correlates strongly with the observed structural and electrical transitions.