Spectroscopic and magnetic studies of erbium doped phosphate glass embedded with natural ferrite oxide nanoparticles

Abstract

Erbium doped zinc phosphate glass embedded with natural Fe3O4 nanoparticles having a composition of (69-x)P2O5 - 30ZnO - 1Er2O3 – (x)Fe3O4, where x = 0, 0.5, 1.0, 1.5, 2.0 mol% has successfully been prepared by melt quenching technique. It was found that the color of the glass varies from pink (without natural Fe3O4 nanoparticles) to dark brown (2 mol% natural Fe3O4 nanoparticles). The change in color indicates that the natural Fe3O4 nanoparticles has already incorporated in the unit structure of the forming glasses. The amorphous structures of the glass sample were evident by the XRD analysis. The density and molar volume of the glass samples were found in the range of 2.75 - 2.89 g/cm3 and 45.89 - 44.30 cm3, respectively. The optical absorption edge was studied by using the UV-Vis spectroscopy. The optical band gaps for direct and indirect transitions and also Urbach energy varied in the range of 4.454 – 3.349 eV, 4.229 – 3.278 eV, and 0.637 – 0.233 eV, respectively were found to decrease with the increase of natural Fe3O4 nanoparticles contents. The emission spectrum was recorded using the photoluminescence spectrometer at room temperature. The emission spectra for 478 nm excitations displayed two prominent peaks centered at 532 nm and 634 nm that originate from 4S3/2 ? 4I15/2 and 4F9/2 ? 4I15/2 transitions, respectively. In addition, the intensity of luminescence spectra tends to quench the emission band with the increasing concentration of the natural Fe3O4 nanoparticles. The crystallite size of natural Fe3O4 nanoparticles was calculated using Debye-Scherrer formula and the results were compared with the size of nanoparticles obtained from TEM. The average diameter of the Fe3O4 nanoparticles of about 26 - 31 nm was calculated using Debye-Scherrer method and this value was about the same with that obtained by TEM micrographs. The TEM micrograph revealed the presence of spherical and homogenous distribution of natural Fe3O4 nanoparticles. Vibrating sample magnetometer (VSM) measurement showed that magnetization of glass increased with applied fields and showed paramagnetic and ferrimagnetic behavior.