Addition Of GeO2 Research Articles

Low‐Coordination Crystallographic Lattice Engineering to Discover Ce3+‐Activated Ultra‐Wide Visible‐to‐Near‐Infrared Luminescent Materials

AbstractDevelopment of ultra‐broadband visible‐to‐near‐infrared (VIS‐NIR) luminescent materials is a challenging but rewarding endeavor, as they are highly desirable for a number of applications in photonics, optoelectronics, and biological sciences. Nevertheless, to date, rare earth‐doped phosphors that can be efficiently excited by blue light and produce broadband emission in the VIS‐NIR regions remain scarce. In this study, a series of Ce3+‐doped Ba3M4O9 (M = Sc, Lu, Y) broadband luminescent materials are designed based on low‐coordination crystallographic lattice engineering. Among these materials, Ba3Y4O9:Ce3+ produces a continuous ultra‐wide VIS‐NIR emission (λem = 660 nm) in the range of 500–950 nm under 410 nm light excitation. This emission wavelength is the longest among those observed in Ce3⁺‐doped oxide materials. Structural refinement, theoretical calculation, and spectral analysis demonstrate that this VIS‐NIR broadband emission is attributed to the occupying multiple distorted octahedral lattice sites by Ce3+ in Ba3Y4O9. Several strategies are employed to enhance the luminescence intensity and thermal stability of this material, including the use of carbon paper coating, the incorporation of co‐solvents, and the addition of GeO₂ or ZrO₂. Furthermore, the as‐prepared materials demonstrate multifunctional applications in white light‐emitting diodes (WLED), night vision, and fluorescent thermometers. This study offers insights into the design of Ce3+‐doped ultra‐wide VIS‐NIR light‐emitting materials.

Enhanced luminescence of CaO:Eu2+ red phosphor in glass for high-power warm LED

Highly emissive and stable red phosphors are vital for the warm Light Emitting Diode (LED). Herein, blue-light-excited CaO:Eu2+ red phosphors were prepared using the carbonation method, coupled with the double crucible carbon reduction technology. The addition of GeO2 and SnO2 significantly enhanced the photoluminescence (PL) intensity and quantum efficiency. Furthermore, a phosphor-in-glass (PiG) made from an improved luminescent CaO:Eu2+ was developed and utilized for LED applications. Such PiG samples considerably improved the stability of CaO:Eu2+ phosphors. The excellent stability, high color rendering index (Ra) value of 87.7 and low correlated color temperature (CCT) of 4469 K confirmed the resulting CaO:Eu2+-based PiG as a promising material for white light-emitting diodes (WLEDs).

Characterization of the α-relaxation and gel-like dynamics in mixed network forming (GeO2)x(NaPO3)100-x glass melts by photon correlation spectroscopy

Dynamic light scattering investigations of the α-relaxation in network-forming (GeO2)x(NaPO3)100-x glass melts is reported for x = 0 to 40 mol% GeO2. Addition of GeO2 results in an increased density of bridging oxygen bonds. This monotonically increases the glass transition temperature but generates complex changes to the glass forming fragility which initially decreases with increasing GeO2 but increases again at higher GeO2 contents. A resolution to this odd fragility behavior is obtained by applying a coarse-graining procedure used previously in sodium germanate melts to arrive at a topological network connectivity for which fragility exhibits a universal dependence. Also observed in the light scattering measurements is a secondary relaxation, several orders of magnitude slower than that of the α-relaxation, which we tentatively attribute to gel-like anomalous diffusion of Ge crosslinks formed between phosphate chains.

Radiation attenuation attributes for BaO-TiO2-SiO2-GeO2 glass series: a comprehensive study using Phy-X software

Abstract The radiation-shielding attributes of six glass samples with BaO-TiO2-SiO2-GeO2 compositions were examined. Using the Phy-X software, the radiation shielding factors for the proposed glasses were reported. The transmission factor (TF) was calculated for various glass thicknesses, and the findings showed that the TF reduces as the glass thickness increases. The transmission of the photon decreased for BTGS55 from 0.83 to 0.49 at 0.284 MeV and from 0.93 to 0.73 at 0.826 MeV as the sample thickness increased from 0.4 to 1.6 cm. The findings of the radiation protection efficiency (RPE) indicated that a thick glass sample absorbs more photons, suggesting that less radiation passes through the glass, improving RPE. Furthermore, the BTGS0 glass has a higher RPE than the BTGS55 glass, indicating that the glass is more effective at blocking incoming radiation when it contains more GeO2. The BTGS55 sample has the lowest RPE and the greatest TF, whereas the BTGS0 glass has the highest RPE and lowest TF. The tenth value layer (TVL) was also obtained, and it was found that TVL rises with energy, peaking at 1.33 MeV and varied from 9.437 to 11.519 cm. The minimal TVL, in contrast, is estimated to range between 3.245 and 3.890 cm and it occurs at 0.284 MeV BTGS0 has the lowest TVL after the addition of GeO2, which lowers the TVL.

Optimization of persistent luminescence performance of zinc gallogermanates

X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal analysis, and X-ray photoelectron spectroscopy, combined with instrumental analysis, have been employed to identify and characterize the physical differences between Zn3Ga2GeO8 (ZGGO-s, s as in stoichiometric) and Zn3Ga2Ge2O10 (ZGGO-e, e as in excess) solid solutions. The two materials differ in the addition of GeO2 (in the case of the ZGGO-e sample) to the solid solution of ZnGa2O4 and Zn2GeO4. The optimum sintering temperature for these materials is 1000 °C. The photoluminescence spectra comprise a broad feature between 400 and 600 nm which is slightly red-shifted in the case of ZGGO-e. Notably, ZGGO-e exhibits superior performance for both the intensity and duration of persistent luminescence at room temperature, with emission maximum at 515–517 nm. The performance of the chromium-doped sample, with persistent luminescence emission at 697 nm, is also superior for ZGGO-e. The reasons behind such a significant enhancement of persistent luminescence performance for ZGGO-e sample were investigated in this paper. We have found out that long persistent luminescence in both samples is governed by trap depth distributions. In the case of ZGGO-e, the addition of GeO2 promotes the formation of deeper traps changing the shape of the resulting trap distribution and hence improving the room temperature persistent luminescence of this compound.

Refractive Index and Abbe Number Tuning via 3D Printable Optical Quality Silica–Titania–Germania Glasses

The development of optical quality GeO2–TiO2–SiO2 glasses compatible with direct ink writing (DIW) 3D printing is reported in this study. Colloidal GeO2 and TiO2–SiO2 core–shell feedstocks are prepared by a sol–gel method and converted to printable inks for DIW. Printed inks are subsequently densified to glass using heat treatment at temperatures up to 1100 °C in air. A series of print‐compatible glass compositions are prepared, yielding transparent glass with the highest refractive index n = 1.576. Herein, it is shown that more TiO2 can be incorporated into the glass without haziness or scattering through the addition of GeO2. The mechanisms for this are discussed, and it is shown that crystallization persists in these glasses despite the lack of visible light scattering. Finally, the combination of both TiO2 and GeO2 into a ternary glass also is used to independently tune the dispersion properties of the glass, as demonstrated by measured refractive indices and Abbe numbers, which has potential implications for 3D‐printed optics.

Tunable broadband photoluminescence from bismuth‐doped calcium aluminum germanate glasses prepared in oxidizing atmosphere

AbstractTunable photoluminescence (PL) from transparent inorganic glass matrices is of interest for applications demanding a semitransparent photoconverter that does not elastically scatter incoming light. For this purpose, bismuth (Bi)‐doped optical materials exhibit unique spectral characteristics in terms of bandwidth and emission tunability. Here, we demonstrate a facile route for preparing such converters from Bi‐doped calcium‐aluminate and calcium‐aluminogermanate glasses. These glasses offer tunable PL across the near violet and visible‐to‐near‐infrared (NIR) spectral range, with an emission lifetime in the range of 300 μs. The addition of GeO2 exerts a decrease in optical basicity, which in turn enables the stabilization of NIR‐active low‐valence Bi species for broadband NIR PL.

Self-reduction mechanism and luminescence properties of Eu2+-Eu3+ doped strontium pyrophosphate

A series of Sr2P2O7:Eu2+-Eu3+ phosphors were successfully synthesized by the high temperature solid state method. The experimental results show that the existence of different network formers (SiO2, GeO2) has a certain influence on the microstructure and luminescent properties of the phosphor. It is interesting that the addition of SiO2 and GeO2 can dramatically improve the luminous intensity of Eu2+. By introducing Li+ or Na+ to compensate for vacancy defects, the purpose of harmonizing the luminescent color of the phosphor can be achieved. In this paper, Eu2+ / Eu3+ co-activated Sr2P2O7 phosphors have good luminous properties and can be adjusted through a variety of channels. Therefore, Sr2P2O7: Eu2+-Eu3+ phosphors can be an ideal choice for a new type of luminescent material.

Germanate oxide impacts on the optical and gamma radiation shielding properties of TeO2-ZnO-Li2O glass system

In this work, a series of tellurite glass combined with various concentrations of germanium oxide was fabricated according to the formula of (70-x)TeO2-xGeO2–20ZnO-10Li2O where x = 5, 10, 15 and 20 mol% via utilizing the melt-quench method for possible use in a radiation shielding applications. X-ray diffraction and Attenuated Total Reflectance Fourier Transform Infrared was employed to investigate the structure of the synthesized glasses. The density and Poisson's ratio for current samples reduced gradually from 5.221–5.008 g.cm−3 and 0.134–0.131, respectively, while the enhancement in bandgap values from 3.700–3.872 eV with addition of GeO2 is observed. The linear attenuation coefficient values at 0.015 MeV are 230.123 and 236.832 cm−1 for samples TG1 and TG4, respectively. Moreover, the lowest half-value layer attained via TG1 and raises from 0.0030 to 3.6684 cm while the highest HVL attained by TG4 and raises from 0.0029 to 3.9696 cm.

Influence of GeO2 on the microstructure and electrical properties of TiO2–Nb2O5–Ho2O3 –SiO2 varistors

TiO2 varistor ceramics co-doped with GeO2, Ho2O3, Nb2O5 and SiO2 were prepared by a conventional solid-state method. Meanwhile, the effects of GeO2 on the microstructure, varistor properties and dielectric properties were investigated in details. The SEM-EDS results revealed that the addition of GeO2 could induce more Nb5+ and Ho3+ ions to dissolve into TiO2 matrix and make Ho3+ ions well-distributed. Moreover, the incorporation of GeO2 significantly improved the dielectric properties. All samples showed a good temperature (−150–200 °C) and frequency(100 Hz–100 kHz) stability of dielectric properties and the sample with 0.9 mol% GeO2 obtained a giant dielectric constant about 2.68 × 105. Besides, the doping of GeO2 was found to be capable of reducing the breakdown voltage and increasing the nonlinear coefficient as well. Particularly, the 0.3 mol% GeO2-doped sample possessed a low breakdown voltage of 2.7 V/mm and the one doped with 0.6 mol% GeO2 showed the maximum nonlinear coefficient value of 6.7.

Investigating the effect of germanium on the structure of SiO2-ZnO-CaO-SrO-P2O5 glasses and the subsequent influence on glass polyalkenoate cement formation, solubility and bioactivity

A series of germanium (Ge)-containing glasses were synthesized based on a starting glass composition of SiO2-ZnO-CaO-SrO-P2O5. Additions of GeO2 (6 and 12 mol%) were incorporated at the expense of SiO2, which retained the amorphous character, and each glass was processed to present similar particle size and surface area. Glass characterization using x-ray photoelectron spectroscopy (XPS) and magic angle spinning nuclear magnetic resonance (MAS-NMR) determined that the addition of GeO2 increased the fraction of lower Q-speciation and subsequently the concentration of non-bridging oxygens (NBO). Glass Polyalkenoate Cements (GPC) were formulated from each glass with 40, 50 and 60 wt% PAA, and presented time dependent solubility profiles (1, 10, 100, 1000 h) for the release of Si4+ (4–140 mg/l), Ca2+ (1–8 mg/l), Zn2+ (<6 mg/l), Sr2+ (2–37 mg/l), PO43− (2–43 mg/l) and Ge4+ (20–911 mg/l) and attained pH values close to 7.5 after 1000 h. Ge-GPCs containing 40 wt% polyacrylic acid (PAA) presented appropriate working time (Tw) and setting times (Ts), and the corresponding compressive strengths ranged from (14–30 MPa). The Ge-GPCs (40, 50 wt%) presented a linear increase (R2–0.99) with respect to time. Simulated Body Fluid (SBF) testing resulted in the Ge-GPCs encouraging the precipitation of crystalline hydroxyapatite on the GPC surface, more evidently after 100 and 1000 h incubation.

Enhanced NIR photoemission from Bi‐doped aluminoborate glasses via topological tailoring of glass structure

AbstractBismuth (Bi)‐doped laser glasses with broadband emission are of current interest in the fields of sensing, bio‐imaging, and photonics. For practical applications, it must be considered how to improve the emission efficiency, in particular, for borate glasses with wide glass‐forming range, low melting point, and excellent fiberizing ability. Herein, we experimentally demonstrate that addition of GeO2 to aluminoborate glasses can effectively enhance Bi NIR emission by more than 300 times with prolonged decay time (~500 μs) and good homogeneity, which is, to our best knowledge, seldom achieved in Bi‐doped borate multi‐component glasses. The addition of second glass‐former GeO2, as revealed by detailed optical and structural analysis, leads to the facile regulation on local glass structure, forcing the conversion of aluminum species from AlO5 and AlO6 to AlO4 and consequently pushes the conversion of Bi3+ to Bi+ and Bi0 and stabilizes Bi NIR centers, which finally results in highly enhanced Bi NIR emission. We believe these results could contribute to designing Bi‐activated multi‐component laser glass and fibers with efficient NIR photoemission.

Incorporating Germanium Oxide into the Glass Phase of Novel Zinc/Magnesium-Based GPCs Designed for Bone Void Filling: Evaluating Their Physical and Mechanical Properties

The structural role of Germanium (Ge), when substituting for Zinc (Zn) up to 8 mol % in the 0.48SiO2–0.12CaO–0.36ZnO–0.04MgO glass series, was investigated with respect to both the glass chemistry and also the properties of glass polyalkenoate cements (GPCs) manufactured from them. The Network connectivity (NC) of the glass was calculated to increase from 1.83 to 2.42 with the addition of GeO2 (0–8 mol %). Differential thermal analysis (DTA) results confirmed an increase in the glass transition temperature (Tg) of the glass series with GeO2 content. X-ray photoelectron spectroscopy (XPS) showed an increase in the ratio of bridging oxygens (BO) to non-bridging oxygens (NBO) with the addition of GeO2, supporting the NC and DTA results. 29Si magic angle spinning nuclear magnetic resonance spectroscopy (29Si MAS-NMR) determined a chemical shift from −80.3 to −83.7 ppm as the GeO2 concentration increased. These ionomeric glasses were subsequently used as the basic components in a series of GPCs by mixing them with aqueous polyacrylic acid (PAA). The handling properties of the GPCs resulting were evaluated with respect to the increasing concentration of GeO2 in the glass phase. It was found that the working times of these GPCs increased from 3 to 15 min, while their setting times increased from 4 to 18 min, facilitating the injectability of the Zn/Mg-GPCs through a 16-gauge needle. These Ge-Zn/Mg-GPCs were found to be injectable up to 96% within 12 min. Zn/Mg-GPCs containing GeO2 show promise as injectable cements for use in bone void filling.

Optical properties of Pb1 − xSnxSe quantum dots (QDs) in silicate glasses dictated by GeO2 concentrations

Effects of SnO addition on the optical properties of Pb1−xSnxSe quantum dots (QDs) were investigated as a function of GeO2 content [GeO2] in germanosilicate glasses. Addition of SnO resulted in a red-shift of the absorption bands from QDs at [GeO2]<20mol%, but in a blue-shift at [GeO2]≥20mol%. Addition of GeO2 to the glass caused a large decrease in its viscosity, so it increased diffusion coefficient (D); as a result the amount of Sn in Pb1−xSnxSe QDs increased. D of Sn2+ was ~560 times higher in the glasses with [GeO2]=40mol% than in the glass with no GeO2. The differences in Sn content in QDs affected their bandgap.

Effect of glass former (B2O3, SiO2, GeO2 and P2O5) addition to Fe2O3-Bi2O3 glass on pH responsivity

The effect of glass former (constituent capable to vitrify by itself such as B2O3, SiO2, GeO2 and P2O5) addition to Fe2O3-Bi2O3 (FeBi) glass on pH responsivity (pH sensitivity and pH response time) was investigated in order to develop novel pH responsive, hydrophobic glasses. Additionally, the effect of glass composition on pH sensitivity of Fe2O3-Bi2O3 glasses was investigated in order to develop contaminant-free reference electrodes with very low pH sensitivity. A small amount of B2O3 and SiO2 drastically increased the pH sensitivity. The addition of glass formers of 20 mol% provided high pH sensitivity (>90%) in any of the glass formers. Although all glass formers increased their contact angle with water for Fe2O3-Bi2O3 glass, the addition of GeO2 was most effective. Most of the Fe2O3-Bi2O3-GeO2 (FeBiGe) glasses with 20–30mol% GeO2, which serve as a working electrode, had compatibility between high pH sensitivity and a high contact angle with water (100°). However, certain Fe2O3-Bi2O3 glasses with approximately 20 mol% Fe2O3 showed low pH sensitivity (<10%). These FeBi glasses are considered to serve as contaminant-free reference electrodes, whereas KCl aqueous solution, as a contaminant, gradually leaks in commercial reference electrodes (Ag/AgCl immersed in KCl aqueous solution). Since the novel pH complex glass electrodes, consisting of a FeBiGe working electrode and a FeBi reference electrode, resist fouling of itself and serve as contaminant-free glass electrodes, these electrodes are expected to be highly useful in biological systems and drug development.

Optical band gap and structural study on GeO2- and Y2O3-doped barium aluminoborate glasses

A series of barium borate-based glasses containing Al2O3, GeO2 and Y2O3 were prepared by conventional method of glass melting and annealing. The prepared glasses were investigated through optical, FTIR, density and molar volume measurements. The optical absorption spectra reveal three characteristic UV absorption peaks at about 213, 240 and 308 nm. The optical absorption measurements were used to estimate direct and indirect transition of optical band gap (Eopt), Urbach energy (ΔE) and the refractive index (n).Values of the optical parameters are found to be related to the structural changes that are taking place in the prepared glasses. The deconvoluted vibrational modes identified in the IR spectrum illustrated the conversion of triangular BO3 structural units to BO4 tetrahedral units with the addition of GeO2 or Y2O3. The formation of non-bridging oxygen atoms is assumed to lead to provide some favorable properties, mainly the optical properties and semiconducting behavior of the prepared glassy samples. Density and molar volume data are found to be dependent on the rigidity of the glass network.

Structural, mechanical and optical investigations in the TeO2-rich part of the TeO2–GeO2–ZnO ternary glass system

Stable glasses are successfully synthesized in the TeO2-GeO2-ZnO system at 850 °C by the melt-quenching method and the glass forming domain is determined in the TeO2-rich part of the diagram. The thermal study, carried out using differential scanning calorimetry, reveals that the glass transition temperature, as well as the thermal stability, increases with the addition of ZnO or GeO2. Bulk glass samples are elaborated within two series of compositions, corresponding to fixed concentrations in GeO2 (respectively 5 or 10 mol. %), and to various contents in ZnO. Structural changes caused by the ZnO addition are discussed based on Raman spectroscopy data. A progressive but very moderate network depolymerization is shown with increasing amount of ZnO. However, two different regimes can be identified, depending on the ZnO content. It is believed that ZnO acts as a network modifier for compositions below 20 mol. %, and starts to participate as a glass network former over such concentration. It is well evidenced that GeO2 contributes to the increase in Young's modulus E, evaluated from ultrasonic echography measurements. In addition, this oxide favors the network reticulation detected by the decrease of the Poisson ratio and the increase of the fractal bond connectivity. However, the role of ZnO is more complicated and will be extensively discussed. The decrease in the atomic packing density Cg probably explains the global evolution of E as a function of ZnO content. The refractive indices and optical band gap energies are extracted from UV-Visible-NIR optical transmission data. For the studied glasses, it is found that the transmission threshold decreases with larger ZnO contents, reflecting the increase in the optical band gap value. Refractive index is finally seen to decrease as a function of both ZnO and GeO2 contents. Such variation is explained by the decrease of the molar electronic polarizability, and by the lower optical basicity values known for TeO3 entities in comparison to TeO4 units.

Enhanced photodegradation of dyes on Bi2O3 microflakes: Effect of GeO2 addition on photocatalytic activity

Visible light active, bismuth oxide microflakes are synthesized by the calcination of bismuth carbonate prepared by the reaction between bismuth nitrate and sodium carbonate. Bi2O3 microflakes comprise of single phase, tetragonal, beta phase having a particle size of 0.10–0.50μm. SAED results suggest that the microflakes are single crystalline in nature. Considerable visible light absorption is exhibited by this material owing to its narrow band gap of 2.30eV. A rapid photocatalytic degradation of Acid violet 7 and Indigo carmine (anionic dyes) is brought about by Bi2O3 as compared to P25. The photocatalytic activity of Bi2O3 for the degradation of a cationic dye, Rhodamine B, is less than that of P25, but increases significantly with the addition of commercial GeO2 powder to the aqueous suspension. The improved photodegradation of dyes except Rhodamine B is correlated to the enhanced adsorption of the dyes on the synthesized Bi2O3. The enhanced photocatalytic activity of Bi2O3 by the addition of GeO2 for Rhodamine B degradation is attributed to the improved transport of photogenerated electron in the system resulting in enhanced electron–hole separation.

Effect of germanium oxide on the structure and properties of lithium borophosphate glasses

Lithium borophosphate glasses with addition of germanium oxide were studied along the compositional series (100−x)[0.5Li2O–0.1B2O3–0.4P2O5]–xGeO2, with x=0–25mol.%. Their properties (density, glass transition temperature, coefficient of thermal expansion, chemical durability) were measured and their structure was studied by 31P and 11B MAS NMR spectroscopy and Raman spectroscopy. The addition of GeO2 to the parent borophosphate glass results in an increase of their glass transition temperature, while their chemical durability only slightly decreases. 31P MAS NMR and Raman spectra reflect the depolymerization of phosphate chains by the incorporation of GeOn polyhedra. 11B MAS NMR spectra reveal the formation of mixed structural units B(OP)3(OGe) in the borophosphate glasses and the decomposition of 11B MAS NMR spectra brings quantitative data on the number of BO3 and B(OP)3(OGe) structural units. A small amount of BO3 trigonal units is formed in the glasses as well.

Influence of germanium oxide addition on the electrical properties of Li2O–B2O3–P2O5 glasses

Lithium ion transport upon the addition of germanium oxide in a series of mixed glass former lithium borophosphate glasses has been investigated. The electrical and dielectric properties of (100 − x)[0.5Li2O–0.1B2O3–0.4P2O5]–xGeO2 with 0–25 mol% GeO2 glasses have been studied over a wide temperature (183–523 K) and frequency range (0.01 Hz–1 MHz). The increase in dc conductivity with the addition of GeO2 is attributed to the formation of ion conducting channels arising from the structural modification and formation of the P–O–Ge linkages, resulting in an easy migration of Li+ ions along these bonds. At higher GeO2 content glass network becomes more densely packed and ionic conductivity is slightly hindered as a consequence of the increase of bonding forces inside the network. Such a decrease in the conductivity is more reflection of the stronger cross-linkage in the glass network than that of the slight decrease in the Li+ ion concentration. The electrical modulus formalism is used to describe the dielectric relaxation. The scaling of the ac conductivity results in an excellent collapse onto common master curve whereas the electrical modulus spectra showed slight deviation indicating the distribution of relaxation times caused by the presence of various structural units in the glass network.