Fabrication and assessment of structural, optical and ligand field relations of silicate glass activated by Ni2+ ions

Here, silicate glass system was prepared and investigated for different optical applications. We report structural
and optical investigation of silicate glass via x-ray diffraction, energy dispersive x-ray, mass density, infrared
spectra, optical spectra, ligand field environment and non-linear optical properties. Through this work, the lead
oxide addition at the expense of silica content was prospected. After confirming the glass forming ability and
quality and its chemical composition by X-ray diffraction and EDX, structural variations were witnessed such as
highly increased mass density by 30 % and enhanced bond density by 20 % due to lead oxide addition. In
addition, different structural groups are related to lead and silica ions were revealed to form the main backbone
of current glass network. The highly dominant of lead ions functional groups are consistent with the increased
density of glass. Optically, absorption bands of nickel ions support best performance of silicate glass in optical
applications within visible and near infrared regions. Using these absorption bands of Ni2+ ions, the ligand field
strength (10Dq) was found to increase from 7752 to 8065 cm− 1, while the Racah B and C parameters were
decreased from (716–617 cm− 1) and (2848–2478 cm− 1), respectively. These behaviours explain the decreased
localization of Ni2+ d-electrons, owing to lead oxide addendum, offering a transition toward a more covalent
character in the Ni2+-ligand bonds. Observably, the lead addition to silicate glass causes a red shift of absorption
edges to some nanometers, reflecting optical band gaps decreases from 3.54 to 2.83 eV and enhanced disorder
degree (i.e., Urbach energy) from 0.20 to 0.27 eV. Overall, the overall optical non-linear properties of these
silicates are enhanced, stemming from an observed enhancement in refractive indices. This work tailors good
structural-optical relations that offer a decent silicate glass, with high quality and performance, for optical
applications