Spectral attributes of Eu3+ doped borotellurite glasses containing Mn3O4 nanoparticles

Highlights: • The Eu³⁺ doped BT glasses containing MNPs has been prepared using melt-quenching method. • TEM result reveals the size of NPs while its planar spacing has been determined by HRTEM. • The luminescence properties of prepared glasses have been investigated. • Judd Ofelt theory has been briefly presented. • The magnetization measurement of glass sample is carried out using VSM and ESR. Glass samples of composition (59-x)TeO₂-30B₂O₃-10MgO-1Eu₂O₃-xMn₃O₄, where x = 0, 0.5, 1.0, 1.5 and 2.0 mol % were prepared using melt quenching method. The Mn₃O₄ nanoparticles (MNPs) concentration dependent spectral properties were determined. XRD pattern verified the amorphous nature of prepared glasses and the presence of MNPs inside the glass matrix. TEM images revealed the nucleation of MNPs of average diameter 15 ± 1 nm. High resolution TEM data confirmed the NPs growth along (1 0 3) crystal plane orientation having lattice spacing ≈ 0.276 nm. Raman spectra displayed a shift in the vibrational modes of TeO₄ and TeO₃ units and thereby confirmed the alteration in the glass network structures mediated by NPs. The bonding characteristics of Eu³⁺ and ligand field parameters were evaluated. The observed increase in the network covalency was attributed to the MNPs assisted changes in the electron distribution. The emission spectra of glass samples revealed five prominent peaks centred at 578 nm, 591 nm, 610 nm, 651 nm and 700 nm which were assigned to the transition from ⁵D₀→⁷F_J (J = 0, 1, 2, 3, 4) states of Eu³⁺ ion. Judd-Ofelt intensity parameters were calculated. The prepared glasses exhibited paramagnetic behaviour. EPR spectra verified the predominant occurrence of Mn²⁺ with effective g ≈ 2.0.