Controlled physical and optical traits of magnesium-zinc sulphophosphate glass: Role of europium ions

Abstract

Trivalent rare earth ions doped sulfophosphate glasses became demanding owing to their several notable attributes that are advantageous for diverse photonic devices. To fulfil such goal, preparation of sulfophosphate glasses with optimized composition by selecting appropriate modifier and subsequent characterizations are essential. Driven by this idea, we synthesized a new series of europium (Eu3+) ions doped magnesium-zinc-sulfophosphate glasses of composition (65–x) P2O5–20MgO-15ZnSO4–xEu2O3 (x = 0.0, 0.5, 1.0, 1.5 and 2.0 mol%) using simple melt-quenching method. As-prepared glasses were characterized thoroughly at room temperature via various analytical techniques to determine the Eu2O3 concentration-dependent physical and optical properties. Transparent (pinkish) and thermally stable glasses were achieved. XRD pattern confirmed the amorphous nature of the studied glasses. Glass density was increased from 2.603 to 2.789 g/cm-3 with the increase of Eu2O3 contents from 0 to 2.0 mol%. FTIR spectra revealed the characteristics bonding vibrations (symmetric and asymmetric stretching and bending of nS (P-O), naS (P-O-P), nS (P-O-P), nS P3O, nS (P-O-P)of phosphate networks linkages. The UV-Vis-NIR spectra of the glasses disclosed six significant absorption peaks centred at 360, 380, 394, 414, 465, and 531 nm accompanied by two NIR peaks around 2091 and 2205 nm allocated to various transitions from the ground state to the excited states of Eu3+ ion. Furthermore, the optical absorption data were further used to calculate the energies of direct (2.0 to 3.85 eV) and indirect (3.74 to 5.0 eV) band gap as well as Urbach energies (0.1909 to 0.2440 eV). The photoluminescence (PL) emission spectra of glasses displayed four peaks entered at 593, 613, 654 and 701 nm assigned to the 5Do→7Fo, 5Do→7F2, 5Do→7F3 and 5Do→7F4 transitions of Eu3+ ion. The PL peak at 613 nm showed the highest emission intensity. The PL intensity was enhanced with the increase of Eu3+ content up to 1.5 mol% and quenched thereafter. It was concluded that controlled physical and optical properties can be obtained by appropriately optimizing the glass composition useful for photonic purposes.