Renata Jadach

Structural and optical properties of antimony-germanate-borate glass and glass fiber co-doped Eu3+ and Ag nanoparticles

In the paper analysis of structural and luminescent properties of antimony-germanate-borate glasses and glass fiber co-doped with 0.6AgNO3/0.2Eu2O3are presented. Heat treatment of the fabricated glass and optical fiber (400 °C, 12 h) enabled to obtain Ag nanoparticles (NPs) with average size 30-50 nm on their surface. It has been proofed that silver ions migrate to the glass surface, where they are reduced to Ag0 nanoparticles. Simultaneously, FTIR analysis showed that heat treatment of the glass and optical fiber increases the local symmetry of the Eu3+ site.

Optical Characterization of Nano- and Microcrystals of EuPO4 Created by One-Step Synthesis of Antimony-Germanate-Silicate Glass Modified by P2O5

Technology of active glass-ceramics (GC) is an important part of luminescent materials engineering. The classic method to obtain GC is based on annealing of parent glass in proper temperature and different time periods. Generally, only the bulk materials are investigated as a starting host for further applications. However, the effect of an additional heat-treatment process on emission and structural properties during GC processing is omitted. Here, we focus on the possibility of obtaining transparent glass-ceramic doped with europium ions directly with a melt-quenching method. The influence of phosphate concentration (up to 10 mol %) on the inversion symmetry of local environment of Eu3+ ions in antimony-germanate-silicate (SGS) glass has been investigated. The Stark splitting of luminescence spectra and the local asymmetry ratio estimated by relation of (5D0→7F2)/(5D0→7F1) transitions in fabricated glass confirms higher local symmetry around Eu3+ ions. Based on XRD and SEM/EDX measurements, the EuPO4 nano- and microcrystals with monoclinic geometry were determined. Therefore, in our experiment, we confirmed possibility of one-step approach to fabricate crystalline structures (glass-ceramic) in Eu–doped SGS glass without additional annealing process.

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.

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%.

Photoluminescence of antimony-germanate-silicate glass doped with europium ions and silver nanoparticles

In the paper we are investigating the interactions between the europium ions and the silver nanoparticles embedded in an antimony-germanate-silicate glass. Modification of Sb<inf>2</inf>O<inf>3</inf> - GeO<inf>2</inf> - SiO<inf>2</inf> - Al<inf>2</inf>O<inf>3</inf> - Na2O glass system by AgNO3 (up to 0.4 mol.%) allows us to obtain a visible effect of thermo-chemical reduction of Ag+ ions and characteristic absorption band localized at the wavelength of 450 nm. The effect of Ag concentration on structural and luminescent properties of fabricated glasses doped with 0.2 mol. % Eu<inf>2</inf>O<inf>3</inf> have been investigated. According to the luminescence analysis, in glass samples with Ag excited at 405 nm, the enhancement of ⁵D<inf>0</inf> → ⁷F<inf>2</inf> transition (616 nm) in Eu³⁺ ions has been observed just after the melting process. Based on these results, an effective embedding way of Ag particles in RE - doped optical fibers has been discussed.

Broadband mid-infrared emission in heavy metal oxide glasses triply-doped with Er 3+ /Ho 3+ /Yb 3+ ions

In the paper heavy metal oxide glass co-doped with Er³⁺/Yb³⁺, Ho³⁺/Yb³⁺ and triply-doped with Er³⁺/Ho³⁺/Yb³⁺ ions have been presented. Glass from Bi<inf>2</inf>O<inf>3</inf> - GeO<inf>2</inf> - Ga2O<inf>3</inf> - Na<inf>2</inf>O system has been characterized in terms of thermal and spectroscopic properties. As a result of energy transfer between lanthanides ions and superposition of emission bands (Er³⁺: ⁴I<inf>11/2</inf> → ⁴I<inf>13/2</inf>, Ho³⁺: ⁵I<inf>6</inf> → ⁵I<inf>7</inf>), broadband luminescence spectra in the range of 2.7 –2.85 µm under 980 nm laser diode excitation was achieved.

Spectroscopic properties and energy transfer in Er/Ag co-doped antimony oxide glass

In this paper antimony-germanate oxide glasses doped with Er3+ and co-doped with Er3+/Ag ions were synthesized and measured in terms of absorbance and near-infrared emission parameters. Series of glasses with different molar concentration of erbium oxide led to the optimal rare earth ion content equal to 0.8 mol% Er2O3. The effect of the incorporation silver ions to the glass matrix on the absorption spectrum in the UV range (Ag: S0 → S1, 350 nm) was confirmed formation of silver ions as a nanoparticles or nanoclusters. In samples co-doped with Er3+/Ag ions decrease of near-infrared luminescence intensity has been observed indicating predominant energy transfer from erbium to silver ions (Er3+ → Ag).

Effect of Ag content on structural and luminescent properties of antimony-germanate-silicate glass doped with Eu3+ ions

The article presents the analysis of local field effect in antimony-germanate-silicate glass doped with europium and silver ions. The effect of AgNO3 concentration on structural and luminescent properties of fabricated glass doped with 0.2 mol. % Eu2O3 have been investigated. XRD and scanning electron microscopy measurements shown that fabricated glass are fully amorphous and the structure of each samples are uniform. Based on the infrared analysis visible effect of Ag ions on MIR absorbance was not observed. According to the luminescence analysis, in glasses with Ag excited at 395 nm the slightly increase of 5D0 → 7F2 transition (613 nm) in Eu3+ ions have been observed only after melting process.

Luminescent properties of germanium-based glasses and optical fiber co-doped with rare earth

In the paper the analysis of white upconversion luminescence obtained as a result superposition of emission bands in germanate glass and double- clad optical fiber co-doped with Yb3+/Tm3+/Ho3+ and Yb3+/Er3+/Tm3+ have been presented. Calculated CIE coordinates for glass co-doped with 0.5Yb2O3/0.4Tm2O3 /0.1 Ho2O3 were x=0.311, y=0.337, Ppump=2.5W and for 0.5Yb2O3/0.25Tm2O3 /0.25Er2O3 co-doped were: x = 252, y = 502. Influence of pump power on the colour coordinates have been also investigated. Thus Yb3+/Tm3+/Ho3+ co-dopant system in germanate glass was used as a core of double-clad optical fiber. Comparative analyses showed differences in luminescence spectra shape of bulk glass and fabricated 0.5Yb2O3/0.4Tm2O3 /0.1Ho2O3 triply doped double – clad optical fiber. Due to partial reabsorption of blue part of amplified spontaneous emission signal propagating band in optical fiber is shifted by 4 nm towards shorter wavelengths. Moreover the I482nm/I545nm luminescence intensity ratio is much higher than in bulk glass.