Effect of annealing on the optical and magnetic properties of Mn3O4 nanoparticles embedded into Eu3+ doped borotellurite glasses

Abstract Tuning the enhanced optical and magnetic properties of rare earth doped glasses by embedding nanoparticles is a never-ending quest. Influences of heat treatment (annealing) in modifying the spectral features of melt-quench synthesized manganese oxide nanoparticles (Mn3O4 NPs) embedded Eu3+-doped borotellurite glasses are reported. The growth of NPs is tuned by varying the annealing time. TEM micrograph reveals the nucleation of heat treated Mn3O4 NPs and SAED manifest their growth along the (1 1 2) crystallographic planes having average size in the range of 5.2 to 21.4 nm. The SPR bands are evidenced in the range 350 to 700 nm that validates the growth of Mn3O4 NPs in the glass matrix. The luminescence spectra reveal four major emission peaks at 591, 614, 651 and 700 nm originating from 7F1, 7F2 7F3, and 7F4 transitions levels, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of Mn3O4 NPs while a quenching is due to the energy transfer from Eu3+ to Mn3O4 NPs. The intensity parameters related to the radiative transitions within 4f configuration of Eu3+ ions are determined and analyzed using Judd-Ofelt theory. The magnetization versus field (M-H) at 12 h of Mn3O4 NPs shows the highest saturation magnetization. The ESR spectrum exhibits resonance signals with effective isotropic g values at 1.9, 3.0 and 4.3 where g at 1.9 are attributed to Mn2+ centers in an octahedral asymmetry and g at 3.0 and 4.3 are attributed to the rhombic symmetry of the Mn2+ ions. Present glass compositions are established to be promising for the development of photonic devices.