Influence of aluminum ions on fluorescent spectra and upconversion in codoped CaF2–Al2O3–P2O5–SiO2:Ho3+ and Er3+ glass system

Abstract

The glasses of the composition 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:1.0Ho2O3/1.0Er2O3 and 20CaF2–xAl2O3–(59−x)P2O5–20SiO2:(0.6Ho2O3+0.4Er2O3) with x varying from 2 to 10 mol % have been synthesized. Optical absorption and fluorescence spectra (in the spectral range 350–2100 nm were studied at ambient temperature. The Judd–Ofelt theory was applied to characterize the absorption and luminescence spectra of Ho3+ and Er3+ ions in these glasses. Following the luminescence spectra, various radiative properties like transition probability A, branching ratio β, and the radiative life time τ for blue (B), green (G), and red (R) emission levels of these glasses have been evaluated. The radiative life times for these transitions of Ho3+ and Er3+ have also been measured. The variations observed in these parameters were discussed in the light of varying coordinations (tetrahedral and octahedral positions) of Al3+ ions in the glass network. The energy transfer between the two rare earth ions (Ho3+ and Er3+) in codoped CaF2–Al2O3–P2O5–SiO2 glass system in the visible and near infrared (NIR) regions has also been investigated as a function of varying concentration of Al2O3. A significant enhancement in the intensities of B, G, and R lines has been observed due to codoping. The quantitative analysis of these results (with the aid of the data on IR and Raman spectral studies) has indicated that the glasses mixed with around 6.0 mol % of Al2O3 is the optimum concentration for yielding the highest quantum efficiency and for maximum energy transfer with low phonon losses.

Influence of tungsten on the emission features of Nd3+, Sm3+ and Eu3+ ions in ZnF2–WO3–TeO2 glasses

“…This instrument contains autocalibrated quadrascopic monochrometer for wavelength selection and quadracentric sample compartment. The light source is high intensity continuous xenon lamp with high sensitivity TE-cooled InGaAs detector with lock-in amplifier and chopper for noise suppression and an additional emission mono with a 600 groove grating blazed at 1.2 m. The system provides unmatched NIR luminescence recording capability from 500 to 2.2 m. The other details of luminescence recording were reported in our earlier papers [39,40]. The fluorescence decay curves were recorded using Jobinyvon spectrofluorolog-3 with pulsed xenon lamp of 450 W. The electron spin resonance (ESR) spectra of the coarsely powdered samples were recorded at room temperature on JEOL JES-TES100 X-band EPR spectrometer; the magnetic field was kept at 5 mT/min and modulated at 100 kHz.…”

Fluorescence features of Sm3+ ions in Na2SO4–MO–P2O5 glass system—Influence of modifier oxide

“…The samples were then optically polished to the dimensions of 1.0 cm  1.0 cm  0.2 cm. The details of the apparatus used and experimental methods adopted for recording the optical absorption, luminescence spectra and lifetime measurements were reported in our earlier papers [12][13][14]. The precision of the optical absorption and luminescent band positions recorded for the present samples is 0.1 nm.…”

The role of coordination and valance states of tungsten ions on some physical properties of Li2O–Al2O3–ZrO2–SiO2 glass system

“…However, some previous studies on other silicate glasses containing Al 2 O 3 have pointed out that Al(6) dominates the glass structure when Al 2 O 3 is present in low concentrations and Al(4) structural units prevail when Al 2 O 3 is present in higher concentrations [35]. Regardless of which participation is chosen, a coordination transformation of Al 3+ in any of the compositions will cause a rapid increase in the relative intensities of IR metal ion and exists in +6 and +5 valence states and its W-O bond in hexavalent oxide is significantly covalent; it is nearly as covalent as of Si-O bond [36].…”