Experimental and molecular dynamics analyses of the replacement of K₂O by SrO on the structural, thermal, and spectroscopic properties of K₂O-SrO-B₂O₃ glasses

In this work, a series of borate glasses with the composition (40-x)K₂O-xSrO-60B₂O₃ (BKSr), with x = 10, 20 and 30 mol% were synthesized by melt-quenching technique, and their structural, thermal and spectroscopic properties, along with a molecular dynamics study, were discussed as a function of the replacement of K₂O with SrO. The amorphous nature of all samples was confirmed by X-Ray Diffraction (XRD) and the physical properties such as density and molar volume indicated that the replacement promotes a greater packing and polymerization of the glass network. Fourier-Transform Infrared (FTIR) analysis revealed the structural changes in glass network as a function of SrO content, indicating BO₃ conversion into BO₄ units, which were confirmed by tetracoordinated boron fraction (N₄). Based on the absorption coefficients, the glasses were found to exhibit broad transparency across the UV to NIR regions (350–2500 nm). Molecular dynamics simulations were employed to obtain information about the glass microstructure and to compare it with experimental data. The results indicate that all glasses presented good properties to be applied in optical devices.