Effects of manganese oxide nanoparticles embedment on optic-magnetic features of magnesium borotellurite doped europium glass

Abstract

This thesis reports the modified optical and magnetic properties of europium doped and manganese oxide nanoparticles (Mn3O4NPs) embedded magnesium borotellurite glass. Glass samples with composition of (59-x)TeO2-30B2O3-10MgO-1Eu2O3-xMn3O4 with 0.0 = x = 2.0 mol % and (59-y)TeO2-30B2O3-10MgO-yEu2O3-1Mn3O4 with 0.0 = y = 2.0 mol % were prepared by melt-quenching technique. The amorphous nature of the glass was determined by X-Ray Diffractometer (XRD) and the presence of Mn3O4 NPs was verified by using Transmission Electron Microscope (TEM) and High Resolution Transmission Electron Microscope (HRTEM). The thermal parameters were determined by Differential Thermal Analyzer (DTA) and spectroscopic properties were measured by Raman, Ultraviolet-Visible (UV-Vis) and Photoluminescence (PL) spectrometer. Magnetic properties were determined by Vibrating Sample Magnetometer (VSM) and Electron Spin Resonance (ESR) spectrometer. The XRD patterns confirmed the amorphous nature of all glasses and TEM images manifested the growth of Mn3O4 NPs with average diameter 15 nm. HRTEM result revealed that the lattice spacing of Mn3O4 NPs was 0.308 nm at (112) plane. The thermal analysis showed that the glass transition temperature, Tg increases with the increase of Mn3O4 NPs and it was attributed to the arrangement of Mn3O4 NPs in the glass matrix. The glass with 1.0 mol % of Mn3O4 NPs and Eu2O3 showed the highest thermal stability, 126 ? and the glass forming tendency, 0.76. The Raman spectra displayed Mn3O4 NPs assisted alteration in the Te-O-Te, BO3, BO4, TeO3 trigonal pyramidal and TeO4 trigonal bipyramidal bonding vibrations. The UV-Vis spectra consist of three bands attributed to absorption from ground state (7F0) to 5D0, 5D1 and 5D2 excited states. Two surface plasmon resonance (SPR) peaks of Mn3O4 NPs were detected at 388 nm and 516 nm. The emission spectra of Eu3+ ion under 390 nm excitations revealed four prominent peaks centered at 591 nm, 614 nm, 651 nm and 700 nm assigned to the transitions from 5DO?7FJ (J=1, 2, 3, 4) states, respectively. Quenching effect in the luminescence intensity due to the incorporation of Mn3O4 NPs was ascribed to the energy transfer from the Eu3+ ion to Mn3O4 NPs. The calculated Judd-Ofelt intensity parameters (O? ?=2, 4, 6), radiative parameter and stimulated emission cross section of Eu3+ ions were found to be strongly influenced by Mn3O4 NPs. Prepared glass systems exhibit paramagnetic behavior with glass magnetization and susceptibility at room temperature in the range of (4.95-13.31×10-2) emug-1 and (4.12-11.09×10-6) emuOe-1g-1 respectively. The ESR spectra of all glass samples exhibit two resonance signals with g values at 1.9 and 4.3 with higher signal observed at 1.9. In addition, correlations between the size of Mn3O4 NPs with saturation magnetization (Ms) and coercivity (Hc) were established. In conclusion, incorporation of Mn3O4 NPs in the glass system has improved the optical and magnetic properties of the glass.