Effect of Bi2O3 on the physical, structural and NIR emission properties of BGG glasses prepared using different melting atmospheres

BGG -Bi2O3 glasses with composition 40GeO2–20Ga2O3–40BaO: x Bi2O3 (x = 0, 1, 2, 4, 6, 8 - 1.0 mol %) were analyzed in terms of optical, thermal properties and structure. The dependence of Bi2O3 content on thermal, structural, and optical properties was investigated by thermal analysis (DSC), Raman spectroscopy, UV–visible and near-infrared absorption, and the M-Line technique to access refractive index values. The results show that with the increase of Bi2O3, the density, the glass transition temperature (Tg), the refractive index, and the optical band gap energy decrease. Different melting atmospheres were added during the syntheses to measure their impact on the photoluminescence of bismuth around 1300 nm. From XPS analysis, photoluminescence measurements indicate that the Bi3+ oxidation state is the main one responsible for the broad near-infrared band from 1000 nm to 1600 nm in these glasses.