Luminescence and spectroscopic studies on Eu3+-doped borate and boro-phosphate glasses for solid state optical devices

Abstract

An addition of Eu3+ ions in Borate glasses (7TiO2 + 3Al2O3 + (60−x)B2O3 + xEu2O3 + 5LiCO3 + 25SrCO3) (where x = 0.05, 0.10, 0.15, and 0.20 mol%) and Boro-phosphate glasses (40B2O3 + 3Al2O3 + (10−x)P2O5 + xEu2O3 + 7ZnO + 5LiCO3 + 10H6NO4P + 25SrCO3) (where x = 0.10 and 0.20 mol%) containing heavy metals, alkali, and alkaline were prepared using a conventional melt quenching technique. The complementary study of the FT-IR and FT-Raman spectroscopic studies proposed the conversion of BO3 ⇔ BO4 in the borate glass network, and the exchange of the PO3 ⇔ PO2 in the boro-phosphate glass network by increasing the Eu3+ ion concentration. The optical characteristics including absorption, linear refractive index (n), Urbach energy (Eu), direct and indirect band gap energies of the prepared glasses were examined and discussed. Judd-Ofelt (JO) theory was used to determine radiative spectroscopic properties such as radiative transition probability (AR), luminescence branching ratio (βR) and stimulated emission cross-section (σPE). Theoretically, the optical gain parameter and gain bandwidth were calculated, which shows their vital role in laser applications. Using CIE chromaticity coordinates, the reddish orange light emission was observed as a proportion of the increase in Eu3+ ions concentration in both glass networks. The measured colour coordinates were utilised to evaluate the correlated colour temperature (CCT), colour purity (Pc), and excitation purity (Pe) of the studied glasses.