Zinc borotellurite glasses doped with lanthanum oxide were successfully prepared through melt-quenching technique. The amorphous nature of the glass system was validated by the presence of a broad hump in the XRD result. The refractive index of the prepared glass samples was calculated by using the equation proposed by Dimitrov and Sakka. The theoretical value of molar refraction, electronic polarizability, oxide ion polarizability and metallization criterion were calculated by using Lorentz-Lorenz equation. Meanwhile, expression proposed by Duffy and Ingram for the theoretical value of optical basicity of multi-component glasses were applied to obtain energy band gap based optical basicity and refractive index based optical basicity. The optical basicity of prepared glasses decreased with the increasing concentration of lanthanum oxide. Metallization criterion on the basis of refractive index showed an increasing trend while energy band gap based metallization criterion showed a decreasing trend. The small metallization criterion values of the glass samples represent that the width of the conduction band becomes larger which increase the tendency for metallization of the glasses. The results obtained indicates that the fabricated glasses have high potential to be applied on optical limiting devices in photonic field. Keywords: Borotellurite glasses, Refractive index, Electronic polarizability, Oxide ion polarizability, Optical basicity, Metallization criterio

Problem statement: Systematic series of ZnO-TeO2 glasses with mole fraction of 0.10-0.40 ZnO content with an interval of 0.05 were studied to obtain their physical and optical properties. Approach: All the glass samples were synthesized by rapid melting quenching method under controlled conditions, while their refractive indices (n) were measured by the EL X-02C high precision ellipsometer. The room temperature absorption of all glass samples were determined using Camspec M350 double beam UV-visible spectrophotometer. The infrared (IR) spectra of each glass samples were recorded with Thermo Nicolet Fourier Transform-Infrared (FT-IR) spectrophotometer. Their physical properties were measured and the amorphous nature was confirmed by the x-ray diffraction technique. Results: The increase of refractive index of the TeO2-ZnO glasses with the addition of ZnO was best explained in terms of either electron density or polarizability of the ions. The absorption edge shift to higher energy (shorter wavelength) with increasing ZnO content was observed in this glass. The optical band gap (Eopt) of zinc tellurite glass decreases with increasing of ZnO content probably due to the increment of Non-Bridging Oxygen (NBO) ion contents which eventually shifted the band edge to lower energies. Conclusion/Recommendation: The physical and optical properties of zinc tellurite glasses were found generally affected by the changes in the glass composition. FTIR spectra of zinc tellurite glass revealed broad, weak and strong absorption bands in the investigated range of wave numbers from 4000-400 cm-1 which associated with their corresponding bond modes of vibration and the glass structure. The addition of ZnO into TeO2 glass network shifted the major band from 626 cm-1 (for pure TeO2 glass) to the band at around 669 cm-1

The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al₂O₃ (Al-5Al₂O₃) has been investigated. Al-5Al₂O₃ nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al₂O₃ nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young’s modulus (E) of Al-5Al₂O₃ nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.

Spinel copper ferrite (CuFe₂O₄) and zinc ferrite (ZnFe₂O₄) nanoparticles were synthesized using a sol-gel self-combustion technique. The structural, functional, morphological and magnetic properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). XRD patterns conform to the copper ferrite and zinc ferrite formation, and the average particle sizes were calculated by using a transmission electron microscope, the measured particle sizes being 56 nm for CuFe₂O₄ and 68 nm for ZnFe₂O_4. Both spinel ferrite nanoparticles exhibit ferromagnetic behavior with saturation magnetization of 31 emug⁻¹ for copper ferrite (50.63 Am²/Kg) and 28.8 Am²/Kg for zinc ferrite. Both synthesized ferrite nanoparticles were equally effective in scavenging 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radicals. ZnFe₂O₄ and CuFe₂O₄ nanoparticles showed 30.57% ± 1.0% and 28.69% ± 1.14% scavenging activity at 125 µg/mL concentrations. In vitro cytotoxicity study revealed higher concentrations (>125 µg/mL) of ZnFe₂O₄ and CuFe₂O₄ with increased toxicity against MCF-7 cells, but were found to be non-toxic at lower concentrations suggesting their biocompatibility.