Replacement of glass-former B2O3 by GeO2 in an amorphous host evidenced by optical methods

Two completely different glass-host matrices containing lead, i.e. borate and germanate glasses doped with erbium were studied. The replacement of glass-former B2O3 by GeO2 in an amorphous host was evidenced by optical methods. The luminescence decay from the⁴I13/2 upper laser state of Er³⁺ ions is relatively short, whereas the up-converted emission signal is reduced definitely in borate glass containing lead due to its high B-O stretching vibrations. The results indicate that germanate glasses containing lead are promising for near-infrared luminescence and up-conversion applications

Influence of heavy metal oxide and activator concentration on spectroscopic properties of Eu 3+, Dy 3+ and Tb 3+ ions in lead borate glasses

Heavy metal lead borate glasses doped with rare earth ions were examined. The influence of heavy metal oxide PbO and activator concentration on luminescence properties of rare earth ions are discussed. Rare earth ions were limited to Eu3+, Dy3+ and Tb3+ which are emitting in the visible light. Increasing concentration of lead oxide in relation to boron oxide causes an increase in R (Eu3+), Y/B (Dy3+) and G/B (Tb3+) spectroscopic factors which correspond to the relative integrated luminescence intensities of 5D0–7F2 /5D0–7F1, 4F9/2–6H13/2 /4F9/2–6H15/2 and 5D4–7F5 /5D4–7F6 transitions, respectively. Moreover, the influence of heavy metal oxide and activator concentration on luminescence decays from excited states of rare earth ions was examined in details

Energy transfer study on Tb3+/Eu3+ Co-activated sol-gel glass-ceramic materials containing MF3 (M = Y, La) nanocrystals for NUV optoelectronic devices

In the present work, the Tb3+/Eu3+ co-activated sol-gel glass-ceramic materials (GCs) containing MF3 (M = Y, La) nanocrystals were fabricated during controlled heat-treatment of silicate xerogels at 350 C. The studies of Tb3+ ! Eu3+ energy transfer process (ET) were performed by excitation and emission spectra along with luminescence decay analysis. The co-activated xerogels and GCs exhibit multicolor emission originated from 4fn–4fn optical transitions of Tb3+ (5D4 !7FJ, J = 6–3) as well as Eu3+ ions (5D0 ! 7FJ, J = 0–4). Based on recorded decay curves, it was found that there is a significant prolongation in luminescence lifetimes of the 5D4 (Tb3+) and the 5D0 (Eu3+) levels after the controlled heat-treatment of xerogels. Moreover, for both types of prepared GCs, an increase in ET e ciency was also observed (from ET 16% for xerogels up to ET = 37.3% for SiO2-YF3 GCs and ET = 60.8% for SiO2-LaF3 GCs). The changes in photoluminescence behavior of rare-earth (RE3+) dopants clearly evidenced their partial segregation inside low-phonon energy fluoride environment. The obtained results suggest that prepared SiO2-MF3:Tb3+, Eu3+ GC materials could be considered for use as optical elements in RGB-lighting optoelectronic devices operating under near-ultraviolet (NUV) excitation

Heavy metal glasses and transparent glass-ceramics : preparation, local structure and optical properties

Heavy metal oxide and oxyfluoride lead silicate glasses doped with rare-earth ions were prepared. Next, they were heat treated in order to obtain transparent glass-ceramics. The rare-earths as optically active ions were limited to trivalent Eu3+ and Dy3+. Correlation between the local structure and the luminescence properties of Eu3+ and Dy3+ ions in the studied glass and glass-ceramic systems was examined using X-ray diffraction, FT-IR and optical measurements. Especially, the ratio of integrated emission intensity of the 5D0–7F2 transition to that of the 5D0–7F1 transition of Eu3+, defined as the luminescence intensity ratio R (Eu3+) as well as the ratio of integrated emission intensity of the 4F9/2–6H13/2 transition to that of the 4F9/2–6H15/2 transition of Dy3+, defined as the luminescence intensity ratio Y/B (Dy3+), have been analyzed in details. Their values are reduced due to part incorporation of rare-earth ions into cubic β -PbF2 crystalline phase. The excitation and luminescence spectra of rare-earth ions in glass samples before and after heat treatment are presented and discussed in relation to potential application in optoelectronics

Wpływ warunków otrzymywania na fizyczne właściwości ceramiki PLZT:Nd3+

The aim of this work was to study the effect of fabrication conditions and neodymium co-doping on the physical properties of (Pb0:98La0:02)(Zr0:65Ti0:35)0:98O3, known as PLZT:Nd3+ ceramics. All ceramic powders of these materials were synthesized by the conventional mixed oxide method, from the high purity raw materials (>99.9%). The bulk ceramic samples were sintered by the pressure less sintering and the hot-uniaxial pressing techniques. The study gives a detailed account of the relationships between doping and preparing conditions on the dielectric and optical properties of obtained ceramic materials. Optimal conditions of PLZT:Nd3+ preparation as well as Nd3+ activator concentration were determined in relation to the potential opto-electronic applications

Excitation and luminescence of rare earth-doped lead phosphate glasses

Excitation and luminescence properties of Eu3+, Tb3+ and Er3+ ions in lead phosphate glasses have been studied. From excitation spectra of Eu3+ ions, the electron–phonon coupling strength and phonon energy of the glass host were calculated and compared to that obtained by Raman spectroscopy. Main intense and long-lived luminescence bands are related to the 5D0–7F2 (red) transition of Eu3+, the 5D4–7F5 (green) transition of Tb3+ and the 4I13/2–4I15/2 (near-infrared) transition of Er3+. The critical transfer distances, the donor–acceptor interaction parameters and the energy transfer probabilities were calculated using the fitting of the luminescence decay curves from 5D0 (Eu3+), 5D4 (Tb3+) and 4I13/2 (Er3+) excited states. The energy transfer probabilities for Eu3+ (5D0), Tb3+ (5D4) and Er3+ (4I13/2) are relatively small, which indicates low self-quenching luminescence of rare earth ions in lead phosphate glasses

Reddish-Orange Luminescence from BaF2:Eu3+ Fluoride Nanocrystals Dispersed in Sol-Gel Materials

Nanocrystalline transparent BaF2:Eu3+ glass-ceramic materials emitting reddish-orange light were fabricated using a low-temperature sol-gel method. Several experimental techniques were used to verify structural transformation from precursor xerogels to sol-gel glass-ceramic materials containing fluoride nanocrystals. Thermal degradation of xerogels was analyzed by thermogravimetric analysis (TG) and di erential scanning calorimetry method (DSC). The presence of BaF2 nanocrystals dispersed in sol-gel materials was confirmed by the X-ray di raction (XRD) analysis and transmission electron microscopy (TEM). In order to detect structural changes in silica network during annealing process, the infrared spectroscopy (IR-ATR) was carried out. In particular, luminescence spectra of Eu3+ and their decays were examined in detail. Some spectroscopic parameters of Eu3+ ions in glass-ceramics containing BaF2 nanocrystals were determined and compared to the values obtained for precursor xerogels. It was observed, that the intensities of two main red and orange emission bands corresponding to the 5D0!7F2 electric-dipole transition (ED) and the 5D0!7F1 magnetic-dipole (MD) transition are changed significantly during transformation from xerogels to nanocrystalline BaF2:Eu3+ glass-ceramic materials. The luminescence decay analysis clearly indicates that the measured lifetime 5D0 (Eu3+) considerably enhanced in nanocrystalline BaF2:Eu3+ glass-ceramic materials compared to precursor xerogels. The evident changes in luminescence spectra and their decays suggest the successful migration of Eu3+ ions from amorphous silica network to low-phonon BaF2 nanocrystals

Rare earth doped lead-free germanate glasses for modern photonics

Lead-free germanate glasses doped with rare earth ions were synthesized and next studied using excitation and luminescence spectroscopy. Rare earths were limited to Pr3+, Eu3+ and Er3+ ions. Several luminescence bands correspond to transitions originating from the 3P0 and 1D2 states of Pr3+, the 5D0 state of Eu3+, the 4S3/2, 4F9/2 and 4I13/2 states of Er3+, respectively. The relatively long lifetime for the upper 4I13/2 laser state of Er3+ suggest that lead-free germanate glasses are promising materials for near-infrared optical amplifiers

Luminescent studies on germanate glasses doped with europium ions for photonic applications

Jacek ̇Żmojda, Marcin Kochanowicz, Piotr Miluski, Piotr Golonko, Agata Baranowska, Tomasz Ragiń, Jan Dorosz, Renata Szal, Gabriela Mach, Bartosz Starzyk, Magdalena Leśniak, Maciej Sitarz, Dominik DoroszGlass and ceramic materials doped with rare earth (RE) ions have gained wide interest in photonics as active materials for lasers, optical amplifiers, and luminescent sensors. The emission properties of RE-doped glasses depend on their chemical composition, but they can also be tailored by modifying the surrounding active ions. Typically, this is achieved through heat treatment (including continuous-wave and pulsed lasers) after establishing the ordering mechanisms in the particular glass–RE system. Within the known systems, silicate glasses predominate, while much less work relates to materials with lower energy phonons, which allow more e cient radiation sources to be constructed for photonic applications. In the present work, the luminescent and structural properties of germanate glasses modified with phosphate oxide doped with Eu3+ ions were investigated. Europium dopant was used as a “spectroscopic probe” in order to analyze the luminescence spectra, which characterizes the changes in the local site symmetries of Eu3+ ions. Based on the spectroscopic results, a strong influence of P2O5 content was observed on the excitation and luminescence spectra. The luminescence study of the most intense 5D0!7F2 (electric dipole) transition revealed that the increase in the P2O5 content leads to the linewidth reduction (from 15 nm to 10 nm) and the blue shift (~2 nm) of the emission peak. According to the crystal field theory, the introduction of P2O5 into the glass structure changes the splitting number of sublevels of the 5D0!7F1 (magnetic dipole) transition, confirming the higher polymerization of fabricated glass. The slightly di erent local environment of Eu3+ centers the results in a number of sites and causes inhomogeneous broadening of spectral lines. It was found that the local asymmetry ratio estimated by the relation of (5D0!7F2)/(5D0!7F1) transitions also confirms greater changes in local symmetry around Eu3+ ions. Our results indicate that modification of germanate glass by P2O5 allows control of their structural properties in order to functionalize the emissions for application as luminescent light sources and sensors

Influence of oxide glass modifiers on the structural and spectroscopic properties of phosphate glasses for visible and near-infrared photonic applications

The e ect of oxide modifiers on multiple properties (structural and spectroscopic) of phosphate glasses with molar composition 60P2O5-(10x)Ga2O3-30MO-xEu2O3 and 60P2O5- (10y)Ga2O3-30MO-yEr2O3 (where M = Ca, Sr, Ba; x = 0, 0.5; y = 0, 1) were systematically examined and discussed. The local structure of systems was evidenced by the infrared (IR-ATR) and Raman spectroscopic techniques. The spectroscopic behaviors of the studied glass systems were determined based on analysis of recorded spectra (excitation and emission) as well as luminescence decay curves. Intense red and near-infrared emissions (1.5 m) were observed for samples doped with Eu3+ and Er3+ ions, respectively. It was found that the value of fluorescence intensity ratio R/O related to 5D0!7F2 (red) and 5D0!7F1 (orange) transition of Eu3+ ions depends on the oxide modifiers MO in the glass host. However, no clear influence of glass modifiers on the luminescence linewidth (FWHM) was observed for phosphate systems doped with Er3+ ions. Moreover, the 5D0 and 4I13/2 luminescence lifetimes of Eu3+ and Er3+ ions increase with the increasing ionic radius of M2+ (M = Ca, Sr, Ba) in the host matrix. The obtained results suggest the applicability of the phosphate glasses with oxide modifiers as potential red and near-infrared photoluminescent materials in photonic devices