Influence of La3+ ions on the structural, optical and dielectric properties and ligand field parameters of Fe3+ hybrid borate glasses

• Published in: Journal of non-crystalline solids 2023-01, Vol.599, p.121981, Article 121981
• Main Authors: Abul-Magd, Ashraf A., Abu-Khadra, Ahmad S., Taha, Ashraf M., Basry, A.A.H.
• Format: Article
• Language: English
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2022.121981

•Entry of La3+ ions as a network modifier led to further structural modifications.•Optical spectra of Fe3+ ions in the visible region can be tuned by La3+ addition.•ESR spectra and Nephelauxetic effect confirmed the covalent nature of Fe3+ ions.•Dielectric constant and dielectric loss coefficient decreased by La2O3 addition.•Fe3+ ions occupied tetrahedral/octahedral sites as confirmed by UV & ESR spectra. The effect of TM/RE mixture (i.e., Fe3+/La3+) on the optical, structural and dielectric features of alkali borate glass was investigated. XRD spectra showed the successful formation of the glass matrix. The La2O3 doping as a network modifier imposed some structural modifications, such as a ∼20% growth in density, ∼15% reduction in molar volume, and an increase in the proportion of BO4 units with a decrease in NBO's ratio. The optical spectra associated with Fe3+ ions occupying the tetrahedral and octahedral sites were subjected to tunability within the visible range by La2O3 additions. Many optical and dielectric features are greatly enhanced; Such as bandgap energy, Urbach energy, linear/nonlinear refractive index, dielectric constant and dielectric loss. The metallization criterion decreased from 0.368 to 0.364 eV−1, reflecting the semiconductor nature of the samples. The nephelauxetic effect confirmed the covalent bonding nature of Fe3+ ions, consistent with the results of ESR spectra.