Magneto-optical properties of europium doped zinc borotellurite glass embedded with nickel nanoparticles

Two series of europium-doped zinc borotellurite glass embedded with nickel oxide nanoparticles (NiO NPs) in the composition (60-x) TeO₂-30B₂O₃-10ZnO-xEu₂O₃ (x = 0.5, 1,1.5, 2, 2.5 mol%) and (58-x) TeO₂-30B₂O₃-10ZnO-2Eu₂O₃-xNiO (x = 0.5, 1, 1.5, 2, 2.5 mol%) are prepared using conventional melt-quenching technique. The amorphous nature of the prepared glasses is confirmed with the aid of the X-ray diffraction technique. Transmission electron microscopy investigations confirmed the presence of spherical and non-spherical NiO NPs with an average size of around 4.6 nm distributed and growing uniformly in the glassy matrix. The lattice spacing was inferred from high-resolution transmission electron microscopy, the estimated distance between the crystal lattice spacing being about 0.198 nm, representing the NiO NPs’ fingerprint identification. The elemental weight fractions of the samples were confirmed by energy dispersive X-ray analysis and these results geared to the determination of adequate atomic number and photon energy response of the samples. The UV–Vis-NIR absorption spectra show seven bands corresponding to transition bands from ground states ⁷F₀ and ⁷F₁ to excited states ⁷F₁ → ⁵G₂, ⁷F₁ → ⁵D₃, ⁷F₀ → ⁵D₂, ⁷F₀ → ⁵D₁, ⁷F₁ → ⁵D₁, ⁷F₀ → ⁷F₆ and ⁷F₁ → ⁷F₆. The infrared to visible frequency down-conversion emission under 395 nm excitation shows six emission bands centered at 519.77 nm, 539.44 nm, 574 nm, 600.25 nm, 634.4 nm, and 683.69 nm, these peaks’ positions are related to the transitions ⁵D₁ \(\to\) $\to$ ⁷F₀, ⁵D₁ \(\to\) $\to$ ⁷F₁, ⁵D₀ \(\to\) $\to$ ⁷F₁, ⁵D₀ \(\to\) $\to$ ⁷F₂, ⁵D₀ \(\to\) $\to$ ⁷F₃ and ⁵D₀ \(\to\) $\to$ ⁷F₄, respectively. The bonding parameter (δ) exhibits a positive sign for all TBZE glass samples, showing that the Eu³⁺ ligand possesses covalent bonding characteristics. The magnetic properties of TBZEN glass were interpreted using VSM, the highest M_s content was obtained when 2 mol% of NiO NP content was embedded in the glass composite and the highest M_r content was obtained for 1.5 mol% of NiO NPs. The maximum possible magnetization ratio M_r/M_s 2.77 was achieved for the glass sample with 1.5 mol% NiO NPs. These findings reveal that the europium-doped zinc borotellurite glass embedded with NiO NPs can be a promising candidate for storage device application.