Spectral attributes of Eu3+ doped borotellurite glasses containing Mn3O4 nanoparticles

Abstract

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?7FJ (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.