Marta Sołtys

Excitation and luminescence of Dy3+ ions in PbO-P2O5-Ga2O3 glass system

Abstract Lead phosphate glasses singly doped with Dy 3+ ions were studied. The samples were prepared in a glove box in order to eliminate hydroxyl groups. Local structures were examined using FT-IR. Excitation and luminescence spectra for Dy 3+ ions in investigated lead phosphate glasses were registered. Luminescence intensity ratio Y/B related to 4 F 9/2 → 6 H J /2 (where J =15, 13) transitions was determined and luminescence lifetime (τ m ) for the 4 F 9/2 state of Dy 3+ ions were also measured.

Terbium-terbium interactions in lead phosphate glasses

Blue and green luminescence spectra of Tb3+ ions in lead phosphate glasses were examined under UV excitation. The green-to-blue luminescence intensity ratio G/B is considerably reduced with decreasing Tb3+ concentration. Thus, blue emission lines are enhanced in comparison to the main 5D4-7F5 green transition of Tb3+. These effects strongly depend on terbium-terbium interactions in lead phosphate glasses. It was confirmed by luminescence decay curve analysis and calculations using the Inokuti-Hirayama model.

Spectroscopic properties of Eu3+, Dy3+ and Tb3+ ions in lead silicate glasses obtained by the conventional high-temperature melt-quenching technique

The luminescence properties of selected rare-earth ions in lead silicate glasses have been studied. Europium, dysprosium and terbium ions were chosen as active dopants. Based on excitation and emission measurements as well as luminescence decay analysis, some spectroscopic parameters for these lanthanide ions were determined. In particular, the intensity ratios R/O (Eu3+), Y/B (Dy3+) and G/B (Tb3+) were calculated. Luminescence lifetimes for the 5D0 state of Eu3+ ions, the 4F9/2 state of Dy3+ ions and the 5D4 state of Tb3+ ions were also determined.

Optical properties of silica sol-gel materials singly- and doubly-doped with Eu3+and Gd3+ ions

Abstract In present work, the optical and structural properties of silica sol-gel glasses and glass-ceramic materials singly- and doubly-doped with Eu 3+ and Gd 3+ ions were investigated. The optical properties of studied systems were determined based on absorption, excitation and emission spectra as well as luminescence decay analysis. Conducted studies clearly indicated a significant enhancement of visible emission originated from Eu 3+ ions as a result of changing the excitation mechanism, via Gd 3+ →Eu 3+ energy transfer. The luminescence intensity R-ratio was analyzed before and after heat-treatment process upon excitation at γ ex =393 nm and γ ex =273 nm. Moreover, the influence of excitation wavelength on luminescence decay time of the 5 D 0 excited state was also analyzed. The Gd 3+ →Eu 3+ energy transfer efficiencies for precursor and annealed samples were calculated based on luminescence lifetime of the 6 P 7/2 level of Gd 3+ ions. The X-ray diffraction measurements were conducted to verify the nature of obtained sol-gel materials. In result, the formation of orthorhombic GdF 3 nanocrystal phase dispersed in amorphous silica glass host was identified after annealing. Obtained results clearly indicated an incorporation of Eu 3+ activators into formed GdF 3 nanocrystals. Thus, conducted heat-treatment process led to considerable changes in surrounding environment around Eu 3+ ions. Actually, it was found that energy transfer phenomenon and heat-treatment process were responsible for significant improvement of Eu 3+ luminescence in studied sol-gel samples.

Spectroscopy and energy transfer in lead borate glasses doubly doped with Tm 3+ and Dy 3+ ions

Lead borate glasses singly and doubly doped with Tm3+ and Dy3+ were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to 1D2→3F4 (blue) and 1G4→3H6 (blue) transitions of Tm3+ as well as 4F9/2→6H15/2 (blue), 4F9/2→6H13/2 (yellow) and 4F9/2→6H11/2 (red) transitions of Dy3+. Moreover, the energy transfer process from Tm3+ to Dy3+ was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm3+. Luminescence lifetimes for the excited states of Tm3+ and Dy3+ ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants.

Investigation of the aluminum oxide content on structural and optical properties of germanium glasses doped with RE ions

In this paper structural and optical properties of Rare Earth doped (RE) gallo-germanate glasses modified with various amount of Al2O3 have been investigated. Glasses doped with Yb3+, Tm3+, and Ho3+ ions were synthesized to study Al2O3 additive influence on their structural and emission properties in the visible spectral region. MIR spectra indicated that the structure of prepared glasses tends to order and its polymerization along with the aluminum content increase. Glass samples consisting of the low molar content of Al2O3 are characterized by a significant contribution of Tm3+ ions in light emission while Ho3+ ions luminescence dominates in samples consisting of the higher molar content of Al2O3. Additionally, investigation of light emission in visible range showed that samples consisting of the low molar content of Al2O3 are characterized by greenish blue light emission whereas light emitted by samples consisting of 15-20 mol% is much closer to the white colour.

Rare earth-doped barium gallo-germanate glasses and their near-infrared luminescence properties

Near-infrared luminescence properties of Nd3+ and Ho3+ ions in barium gallo-germanate glasses have been reported. Several spectroscopic parameters for Nd3+ and Ho3+ ions have been determined from the Judd-Ofelt analysis and absorption/luminescence measurements. Quite large luminescence lifetime, quantum efficiency and stimulated emission cross-section have been obtained for the main 4F3/2 → 4I11/2 (Nd3+) and 5I7 → 5I8 (Ho3+) laser transitions of rare earths in barium gallo-germanate glasses. It suggests that barium gallo-germanate glass is promising for near-infrared laser application at emission wavelengths 1064 nm (Nd3+) and 2020 nm (Ho3+).

Energy transfer and multicolor emission in germanate glasses containing Ce3+ and Pr3+ for white light-emitting diodes

White light emitting devices have attracted great attention for their use in liquid crystal monitor screens and white light emitting diodes (W-LEDs). Glasses singly or doubly doped with lanthanide ions may be good white light emitters. In particular, various glass systems containing Pr3+ were studied from this point of view. In this work, germanate glasses doubly doped with Ce3+ and Pr3+ ions were prepared by traditional melt quenchingtechnique. The excitation and emission spectra of lanthanide ions were measured. The emission bands corresponding to characteristics transitions of Pr3+ and transition of Ce3+ ions from 5d level to 4f levels (2F7/2 and 2F5/2) are quite well observed. It indicates that the energy transfer process between Ce3+ and Pr3+ ions in germanate glasses occurs. From the emission spectra, the Commission Internationale de I’Eclairage (CIE) chromaticity coordinates (x, y) were calculated in relation to potential application for white LEDs. Luminescence decay analysis is also presented and discussed in details. The obtained results suggest the possibility of using these Ce3+/Pr3+ co-doped glass systems for future application to white light generation.

Spectroscopic properties of rare earth doped germanate glasses

Structural and optical properties of Eu3+ doped barium-gallo-germanate glasses modified with antimony and tellurium oxides were investigated. Barium ions are gradually replaced by antimony and tellurium ions to create two glass series. Structural properties of prepared series were established with help of FT-IR spectroscopy, X-ray diffraction method and observation under Scanning Electron Microscope (SEM). MIR spectra of studied glasses indicate a tendency to glass structure polymerization through the observed shift of main band assigned to Ge-O-Ge and Ge-O bonds vibrations. Simultaneously luminescence spectrum of Eu3+ ion (Electric/Magnetic – ED/EM dipole transition intensity ratio) for both glass series presented the increasing tendency to ordering of Eu3+ local environment. It was also proved that tetrahedral [TeO4] units were created in glass structure which were modified with TeO2 when addition exceed 10 mol%. The result indicates decrease of ED/MD ratio as a function of TeO2 content above its 10 mol%.

Near-infrared emission in barium gallo-germanate glasses doped with Pr3+ and co-doped with Ce3+ and Pr3+ for broadband optical amplifiers

Near-infrared emission in barium gallo-germanate glasses containing rare earth ions for broadband optical amplifiers were studied. Among the rare earths, the trivalent praseodymium and cerium ions were selected as an optically active dopants. In order to examine the spectroscopic properties of these glasses doped with Pr3+ and co-doped with Ce3+ and Pr3+ ions the luminescence spectra were registered. The energy transfer processes between cerium and praseodymium ions in barium gallo-germanate glasses have been also investigated. The intense near-infrared luminescence bands corresponding to characteristic transitions of Pr3+ ions in singly and doubly doped glass systems were observed. It has been proved that our glasses exhibit intense 1.5 μm emission originating from 1D2 → 1G4 transition of Pr3+ under direct excitation (445 nm). Moreover, the experimental results indicated that energy transfer between Ce3+ and Pr3+ is not effective for barium gallo-germanate glasses.