Lanthanum-bearing iron lithium borate glass is a quaternary system for oxide glasses and was prepared
via the melt-quenching method. The present article correlates the structure, optical, ligand field and
M€ossbauer data on iron lithium borate glass containing La3þ. The density was measured, while the molar
volume was calculated. Other physical parameters are well-described. With increasing the La2O3 content
within the glass network, infrared spectra analysis reveals structural modifications such as the increase
in BO4 units and the decline in both BO3 units and NBO bonds content. Furthermore, optical absorption
spectra were measured. The absorption spectra disclose a plethora of electronic transitions that are
related to Fe3þ in tetrahedral and octahedral sites, however, Fe2þ phase is not observed in optical spectra,
but it has a clear signature in M€ossbauer spectra. Besides, the glass absorption edges undergo a clear blue
shift, reflecting an increased band gap energy (1.96e2.28 eV). The decline in NBO bonds justifies this
trend. Bewitchingly, the values of crystal field splitting are increased, while the values of Racah parameters
are decreased. This trend is justified by the decline in NBO bonds and increases electron
localization around Fe cations. M€ossbauer spectra confirm the existence of Fe3þ in tetrahedral and
octahedral sites, while Fe2þ exists in only a tetrahedral state. With increasing La2O3 content, the isomer
shift of Fe3þ in tetrahedral sites changes to be 0.312e0.329 mm/s, while the isomer shift of octahedral
Fe3þ is 0.424e0.456 mm/s. These findings coincide with optical data. While the isomer shift of tetrahedral
Fe2þ is 0.902e0.911 mm/s. Our results of structural, optical and ligand field associated with
M€ossbauer spectra open more vistas toward the utility of these samples in the optics realm. |
