Spatially resolved X-ray fluorescence, Raman and photoluminescence spectroscopy of Eu3+/Er3+ doped tellurite glasses and anti-glasses

Strontium tellurite, lead tellurite and bismuth niobium tellurite glasses containing 1 to 2 mol% of Eu3+ and Er3+ were prepared by melt-quenching and found to contain anti-glass inclusions (droplet phase) of size of several micrometers. Anti-glasses are disordered crystals that have long-range order of the cations such as Sr2+, Pb2+, Bi3+, Nb5+ and Te4+ but have a disordered arrangement of the anions (O2-), therefore these materials exhibit sharp peaks in the X-ray diffraction patterns due to the long range cationic order but the Raman spectra show broad bands due to the vibrational disorder. The glass matrix and anti-glass inclusions in the samples were characterized by synchrotron micro-X-ray Fluorescence (XRF), Raman and photoluminescence mapping studies. The XRF line analysis confirmed that the anti-glass and glass matrix phases have equal concentration of metal ions. The samples containing Eu3+ show intense red photoluminescence at an excitation wavelength of 375 nm, while Er3+ doped samples exhibit strong green emission by the up-conversion of infrared photons (980 nm). The spatially resolved XRF, Raman and photoluminescence spectroscopy found that the inclusions and the glass matrix have the same metal ion concentration, short-range order, Te-O speciation and the light emission properties.