MORPHOLOGY, OPTICAL, AND PHOTOLUMINESCENCE PROPERTIES OF Sm DOPED TeO2 NANO CRYSTALLINE POWDERS

In the present research work, Smx (x = 1, 5, and 10 wt.%) doped TeO2 nanostructures (NS) synthesized by the simple chemical precipitation method and characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-(UV)-visible optical absorption studies. X-ray diffraction pattern analysis indicated tetragonal phase and spherical shaped agglomerated morphology observed as Sm concentration increases in the crystal lattice. The UV-visible absorption spectra shift toward longer wavelength and an extension of the wavelength to the visible region for all the concentration of Smx:TeO2 NS as compared to the undoped NS. Photoluminescence (PL) excitation spectroscopy measurements carried out for all concentrations of Smx:TeO2 NS. Smx:TeO2 (x = 10 wt%) displayed strong orange emission (4G5/2 6H7/2) when excited at 325 nm (λexcitation = 325 nm). The intense orange peak that appeared at 380 and 410 nm corresponds to 4F5 configuration of Sm3+ ions in TeO2 host NS. PL efficiency depends on higher separation of electron-hole pairs, a greater number of defects, and larger oxygen vacancies in the Smx:TeO2 NS. The energy transfer from TeO2 to Sm3+ ions are verified, and the relevant mechanism is discussed. Such materials find applications in the white light emission diodes and solid lasers.