Investigation of some structural and spectroscopic characteristics of inverted Alkali–bismuth fluoroborate glass containing holmium ions
摘要
An inverted glass system of sodium bismuth fluoroborate with the composition of (30-x)NaF–40Bi2O3–30B2O3–xHo2O3 was successfully fabricated using the traditional melt-quenching method, where the holmium content was introduced at the expense of the sodium fluoride (NaF) modifier to modify the glass structure and improve the optical and spectroscopic properties. The substitution of NaF with Ho2O3 resulted in an increase in the glass density (ρ) from 4.888 to 5.322 g/cm3. The glass structure consists of BiO3, BiO6, BO3, BO2F, BO4, and BO3F units. The incorporation of Ho3+ ions into the host glass network resulted in the appearance of characteristic spectral absorption peaks within the visible and near-infrared regions. The indirect optical band gap (Eg) values increased from 1.815 eV to 2.360 eV as the Ho2O3 ratio increased from 0 to 7 mol%. The calculated refractive index (no) also varied from 2.804 to 2.595. The contribution of electric and magnetic (DED and DMD) dipole spectral transitions was examined using Judd-Ofelt theory. The intensity parameters follow the order Ω2 > Ω4 > Ω6, indicating an increase in covalent character. The emission probability, branching ratio, and radiative lifetime were calculated utilizing the DED, DMD, and ΩQ=2,4,6 values. The optical gain cross section (Σgain(λ)) highlights the anticipated near-infrared emissions at 1.2 μm and 2.0 μm. Therefore, such glass fabrications could be vital in photonic applications, such as near-infrared emission communication technology and their applications.