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

Abstract

In the present research work, Sm_x (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 Sm_x:TeO₂ NS as compared to the undoped NS. Photoluminescence (PL) excitation spectroscopy measurements carried out for all concentrations of Sm_x:TeO₂ NS. Sm_x:TeO₂ (x = 10 wt%) displayed strong orange emission (⁴G_5/2 ⁶H_7/2) when excited at 325 nm (λ_excitation = 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 Sm_x: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.