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Cesium lead halide (CsPbX 3 , X = Br, I) perovskite nano-crystals (PNCs) with modified compositions were synthesized within boro-germanate glass ceramics to obtain an efficient red color converter for ultra-high definition (UHD) display application. The glass composition and heat treatment conditions were varied to achieve a high photo-luminescence quantum yield (PLQY) under a blue (450 nm) light emitting diode (LED) excitation. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of CsPb(Br/I) 3 PNCs within the glass matrix. A high PLQY of up to 70.5 % was achieved under 450 nm blue LED excitation. The role of composition on the glass structure and PNC formation as well as PL-QY was investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The stability of the CsPb(Br/I) 3 PNC embedded glass (PNEG) against temperature, water, and continuous LED irradiation was examined, and revealed significantly improved photo, chemical and thermal stability compared to colloidal PNCs. Practical feasibility for display applications was demonstrated by fabricating a white LED using the present red PNEG mixed with green CsPbBr 3 PNEG in a remote phosphor-in-silicone structure, showing a wide color gamut of 138.9 % of the NTSC. [ABSTRACT FROM AUTHOR]

The radiation shielding properties of the glass system 32GeO2-15B2O3-3ZnO-5P2O5-45Tb2O3 doped with Ho2O3, Pr6O11, Er2O3, Nd2O3, Dy2O3, and CeO2 ions have been investigated. The linear attenuation coefficient (LAC) of the glasses was calculated using Phys-X software at different energies. It was found that the LAC of the GeO2-B2O3-ZnO-P2O5-Tb2O3 glass system increases after incorporating the RE oxides. The LAC of the samples depends on the types of dopants and the density of the RE oxides. It was found that the glass doped by H2O3 (coded asT45-Ho) has higher LAC than the other glasses with RE, while the glass doped by CeO2 has the lowest LAC. The effective atomic number (Zeff) results demonstrated that the Zeff for the glasses doped with the RE oxides are improved relative to the Zeff for the reference glass (i.e., glass without RE). The glass with Er2O3 (coded as T45-Er) has slightly higher Zeff than the other glasses with RE oxides, while T45-Ce has the minimum Zeff. The role of the energy of the radiation on the Zeff was investigated, and the results showed a reduction in the Zeff when the energy increases from 0.284 to 1.33 MeV. In terms of thickness, The T45 glass (free- RE oxides) showed higher half value layer (HVL) than the other glasses, indicating that the addition of RE oxides lead to decrease the HVL. [ABSTRACT FROM AUTHOR]

Er3+–Yb3+ codoped transparent oxyfluoride germanate glass ceramics (GCs) containing SrF2 nanocrystals (NCs) have been prepared by melt quenching method. We have measured absorption, photoluminescence (PL), and PL decay. The PL spectra excited at 378 nm and 980 nm for 1.53 µm near‐infrared (NIR) and visible emission have been investigated. By using Judd–Ofelt (JO) theory, optical transition parameters have been calculated. Thanks to low phonon energy SrF2 NCs and high fluorine oxyfluoride glass matrix, strong 1.53 µm emission with large measured lifetime (τmeas) are observed. After SrF2 NCs formed, the intensity parameter Ω2 becomes smaller for GC samples, the PL intensity and full width at half maximum increase. Absorption cross section (σa) and emission cross section (σe) at 1.5 µm have been calculated by McCumber theory. The luminescence efficiency (η), effective linewidth (Δλeff), gain bandwidth (σeΔλeff), and figure of merit (σeτm) have been evaluated. The results show excellent optical amplification performance. [ABSTRACT FROM AUTHOR]

In this investigation, a group of different concentrations of molybdenum trioxide-doped borate-germanate-telluride glasses have been synthesized. Four glasses with a composition formula of (35-x) B 2 O 3 -20TeO 2 -10GeO 2 -35MgO-xMoO 3 where x values vary between 5 and 20 mol % have been achieved using the melt-annealing process. X-ray diffraction for the current M1 sample was utilized to prove the glassy nature. FTIR has been measured to understand the glass structure. Many functional group and vibrational bonds were observed. The optical parameters for B 2 O 3 -TeO 2 -GeO 2 -MgO-MoO 3 glass samples were calculated based on absorption spectra recorded in the 200–1100 nm wavelength range. The optical electronegativity (χ) and optical basicity (Λ) were calculated as critical parameters that can be used to evaluate the glass structure. Physical parameters like density, molar volume (V m), packing density (V t), oxygen packing density (OPD), and oxygen molar volume (OMV) were measured and calculated. Hardness (H), Poisson ratio (σ), Fractal bond conductivity (d), and elastic moduli of M1, M2, M3, and M4 glass samples were calculated. Mass attenuation coefficients (MAC) for four synthesized glass samples were reported along with linear attenuation coefficient (LAC) as a function of photon energy. Based on the transmission factor TF %, it shows extremely low percentages at the lowest energy region, dropping to less than 1 % at 0.015 MeV up to 0.08 MeV in all samples. The radiation protection efficiency (RPE) was examined to measure the samples' capacity to attenuate ionizing radiation. [ABSTRACT FROM AUTHOR]

Bismuth germanate glasses were modified with sodium oxide, and the resulting glasses were studied in order to determine the influence of the modifier on their spectral-luminescent properties. The ratios of Bi2O3 and Na2O concentrations at which the infrared luminescence of these glasses is possible were identified. [ABSTRACT FROM AUTHOR]

Samples of germanium borosilicate glasses with chemical formula 50.5B2O3 + 0.5CeO2 + 10SiO2 + (20‐x) CaO + 19Na2O + XGeO2 with 0 (GeO0) ≤ X ≤ 5 (GeO5) mol% were fabricated by using the melt quenching technique. Structure, physical, and optical properties as well as radiation attenuation capacity was examined. XRD data confirmed that GeOX samples were in amorphous state. The density (ρ) of the prepared glass samples increased from 2.24 to 2.55 g/cm3, while the molar volume (Vm) slightly declined from 26.8 to 26.42 cm3/mol. The UV absorption edge shifted to a higher wavelength as the concentration of GeO2 increased. The values of direct band gap (EgDirect)$(\bm{E_g^{Direct}})$ ranged from 3.36 to 2.91 eV, and the indirect (EgIndirect)$(\bm{E_g^{Indirect}})$ ranged from 3.12 to 2.75 eV. Urbach energy (Eu) values fluctuated between 0.65 to 0.16 eV. As the Ge4+ ion increased, the glass sample's refractive index enhanced. Mass attenuation coefficients (MACs) of GeOX samples increased from 6.788 to 10.381 cm2/g at 0.015 MeV. The GeO5 sample possessed the lowest half value layer (HVL) and mean free path (MFP). Effective atomic number (Zeff) of GeOX possessed the same trend of MAC. Results confirmed that the suggested GeOX glasses can be applied in different optical and radiation attenuation applications. [ABSTRACT FROM AUTHOR]

Samples of germanium borosilicate glasses with chemical formula 50.5B2O3 + 0.5CeO2 + 10SiO2 + (20‐x) CaO + 19Na2O + XGeO2 with 0 (GeO0) ≤ X ≤ 5 (GeO5) mol% were fabricated by using the melt quenching technique. Structure, physical, and optical properties as well as radiation attenuation capacity was examined. XRD data confirmed that GeOX samples were in amorphous state. The density (ρ) of the prepared glass samples increased from 2.24 to 2.55 g/cm3, while the molar volume (Vm) slightly declined from 26.8 to 26.42 cm3/mol. The UV absorption edge shifted to a higher wavelength as the concentration of GeO2 increased. The values of direct band gap (EgDirect)$(\bm{E_g^{Direct}})$ ranged from 3.36 to 2.91 eV, and the indirect (EgIndirect)$(\bm{E_g^{Indirect}})$ ranged from 3.12 to 2.75 eV. Urbach energy (Eu) values fluctuated between 0.65 to 0.16 eV. As the Ge4+ ion increased, the glass sample's refractive index enhanced. Mass attenuation coefficients (MACs) of GeOX samples increased from 6.788 to 10.381 cm2/g at 0.015 MeV. The GeO5 sample possessed the lowest half value layer (HVL) and mean free path (MFP). Effective atomic number (Zeff) of GeOX possessed the same trend of MAC. Results confirmed that the suggested GeOX glasses can be applied in different optical and radiation attenuation applications. [ABSTRACT FROM AUTHOR]

Influence of titanium dioxide concentration on thermal properties of germanate-based glasses has been studied. Germanate glasses varying with TiO2 content were examined using DSC methods. The DSC curves exhibit two exothermic peaks, when GeO2 is substituted by TiO2. Based on DSC measurements, characteristic temperatures were determined. The studies demonstrate that glass transition temperature increases, whereas thermal stability parameters are reduced with increasing TiO2 concentration. The DSC curves were also acquired with different heating rates, and the Kissinger method was used to calculate the activation energy. X-ray diffraction analysis for germanate-based glass with TiO2 indicates that crystallization processes are more complex and several phases are formed during annealing. The absorption and emission spectra of glass samples doped with Er3+ ions were also examined before and after annealing process. [ABSTRACT FROM AUTHOR]

To study non-traditional glass materials, this investigation created four glass samples composed of (70-x)B 2 O 3 –20TeO 2 -10GeO 2 -xMgO, where x represents the percentage of MgO with values of 20, 25, 30, and 35 mol%. Glasses with high transparency were produced via the accepted melt quenching and annealing method. The samples underwent X-ray diffraction analysis to confirm their glassy structure. Fourier transform infrared spectroscopy was utilized to examine the glass network's various structural groups. The measuring methodology and theoretical calculations were used to calculate a range of physical and mechanical parameters. The cut-off wavelength, as well as the direct and indirect bandgap, and other optical characteristics of the S1–S4 samples were observed using optical absorption. The work utilized Phy-X to acquire the ionizing absorption parameters. The paper demonstrates various glasses' radiation shielding properties, including the effective atomic number, half- and tenth-value layers, linear attenuation coefficient, mass attenuation coefficient, and mean free path. [ABSTRACT FROM AUTHOR]

Within the scope of the study, glasses co-doped with Sm3+/Gd3+ based on the B2O3–GeO2–Bi2O3 system were synthesized, covering compositions of 40B2O3–40GeO2–(15 – 17)Bi2O3–(3 – 2)Sm2O3–(2 – 1)Gd2O3 and 42.5B2O3–42.5GeO2–(11.25 – 12.75)Bi2O3–(2.25 – 1.50)Sm2O3–(1.500 – 0.075)Gd2O3. An assessment of luminescent characteristics was carried out within the temperature range of 298 – 673 K. Spectral bands of photoluminescence associated with transitions between various Stark sublevels of Sm3+ ions were identified. Redistribution of the fluorescence intensity ratio corresponding to 4G5/2 → 6H9/2 ( λ PL max = 645 nm) and 4G5/2 → 6H7/2 ( λ PL max = 597 nm) transitions was observed. Based on the obtained data, calculations of the fluorescence intensity ratio FIR, as well as relative sensitivity SR, were carried out. The obtained results indicate the promising potential of these glasses as luminescent thermometric materials. [ABSTRACT FROM AUTHOR]

Germanate tellurite glasses doped with Eu3+ and Tb3+ were synthesized by the conventional melt-quenching method. There is no indication of the energy transfer between dopant ions in this host, but the co-dopants exhibit excellent color purity of 100% for Eu3+ and 80% for Tb3+. The co-doped glass exhibits yellow luminescence. The quantum yield of the Eu3+ emission is equal to 23% under 395 nm excitation. The thermal quenching of Eu3+ and Tb3+ luminescence occurs at different temperature ranges, which enables the thermal sensing properties of the material. The relative fluorescence intensity ratio (FIR) sensitivity of 0.16% K−1 was recorded in the wide range of temperatures spanning from −193 °C up to 0 °C. The temperature dependence of the decay times was also studied. The lifetime-based temperature sensitivity was determined to be 0.95% K−1 at 250 °C for Tb3+5D3 level emission and 0.3% K−1 at 225 °C for Eu3+5D1 level emission. [ABSTRACT FROM AUTHOR]

The continuous development of portable devices and new energy vehicles has led to an increasing demand for high‐performance lithium‐ion batteries (LIBs), and anode materials, as a key part of LIBs, are being explored. Germanium‐based anode materials are considered to have good potential for application because of their high theoretical capacity. In this work, a germanium phosphate glass precipitating GeO2 microcrystal was designed and used in LIBs as anode materials for the study. The presence of GeO2 crystals increases the specific surface area and also provides more reaction sites for lithiation reaction, resulting in the capacity of the glass anode. The discharge specific capacity of the germanium‐phosphorus glass anode was as high as 740.9 mAh g−1 after 600 cycles at a current density of 500 mA g−1. Interestingly, the synergistic effect between the glass matrix and the crystals not only increases the cycling capacity but also enhances the cycling stability of the structure. [ABSTRACT FROM AUTHOR]

In this study, we successfully prepared quaternary germanate glasses (Ba x/3 Sr x/3 Ca x/3)Ge (1-x) O 3 (x = 0.1–0.5) using a containerless solidification method. The structure of the germanate amorphous materials was characterized using techniques such as XRD, SEM, TEM and Raman. We evaluated the thermodynamic properties of the amorphous materials using differential scanning calorimetry and investigated their crystallization activation energies. In terms of application performance, we measured electrical conductivity and impedance spectra for the electrical properties, while the optical properties were assessed through the refractive index and transmittance. The results revealed that the (Ba 0.2/3 Sr 0.2/3 Ca 0.2/3)Ge 0.8 O 3 system represented the germanium anomaly point. Due to the highest number of ternary rings and the most compact structure within this system, the values of density, glass transition temperature, refractive index, and bandgap all reached their maximum. As the content of alkaline earth oxides increased, the glass network structure gradually fractured, leading to an increase in non-bridging oxygens and corresponding changes in properties. [ABSTRACT FROM AUTHOR]

Electron beam annealing was carried out to form amorphous and crystalline germanium clusters in GeO[SiO] and GeO[SiO2] films deposited on quartz and mono crystalline silicon substrates. Using electron microscopy, Raman spectroscopy, and light transmission and reflection spectroscopy, the structural transformations of the films and their optical properties were studied. From the analysis of Raman spectra, it was shown that amorphous germanium nano clusters are present in the as-deposited GeO[SiO] film, while they are not observed in the as- deposited GeO[SiO2] film. Regimes of electron beam annealing which are necessary for the formation of germanium nano crystals in GeO[SiO] and GeO[SiO2] films were found. It was shown that, at the same annealing parameters, the fraction of the crystalline phase of germanium in GeO[SiO] films were smaller than in GeO[SiO2] films. In addition, it was found that the fraction of the crystalline phase at the same annealing parameters is larger for films on a quartz substrate than on monocrystalline silicon substrate. The sizes of germanium nanocrystals formed as a result of electron beam annealing were determined from Raman spectra analysis. The proposed method of obtaining amorphous germanium nanoclusters and nanocrystals in films of nonstoichiometric germanosilicate glasses using electron beam annealing can be used to create ordered arrays of such nanostructures. [ABSTRACT FROM AUTHOR]

Er3+ doped high density germanate glasses with compositions of 50GeO 2 -10BaO–10Al 2 O 3 -15Lu 2 O 3 -(15-x) La 2 O 3 -xEr 2 O 3 (x = 0, 0.1, 0.5, 1.0, 1.5, and 2.0, in mol%) have been prepared by the melt-quenching method. The optical and physical properties of the samples were characterized by differential scanning calorimetry (DSC), density, transmittance spectra, photoluminescence (PL) spectra, and X-ray excited luminescence (XEL) spectra. The densities were in the range from 5.90 to 6.07 g/cm3. The strong green emissions around 552 nm of Er3+ were observed upon the excitations of 378 nm light and the X-ray, and the lifetimes of 552 nm emission were in the range of 20.88–96.47 μs. The results show that Er3+ doped high density germanate glasses could be used as potential scintillators for X-ray CT. [ABSTRACT FROM AUTHOR]

Broadband near-infrared (NIR) spectroscopy based on glass-converted light-emitting diodes (gc-LEDs) has been of great interest to multifunctional applications ranging from night vision to chemical industry, stimulating the demand for exploring broadband NIR gc-LEDs with sufficient efficiency stability and aging resistance. Herein, an all-inorganic broadband NIR LEDs based on Te cluster-doped germanate glass is developed. Via adjustment of melting atmosphere and network topology of the glass matrix, active NIR Te cluster centers can be generated and stabilized in germanate glass and show a broad emission at 770 nm with a full width at half maximum (FWHM) of 260 nm under blue light excitation. By combining the Te-doped glass with a commercial blue LED chip, a high-performance NIR gc-LEDs is fabricated with an NIR output power of 14.21 mW@10.1% under a driving current of 400 mA. Particularly, the fabricated NIR-LED device exhibits high efficient stability with a relatively low-efficiency drop of 0.0023 %mA−1, and excellent aging resistance while retaining an electroluminescence intensity up 90 % of their initial value after aging for 480 h under harsh conditions, which is comparable to the commercial phosphors. Finally, its multifunctional application of gc-LEDs is also demonstrated. [ABSTRACT FROM AUTHOR]

In this work we studied the radiation shielding features of Li2O-Sb2O3-PbO-GeO2-Cr2O3 glass systems at different energies ranging from 0.284 to 1.33 MeV. The maximum linear attenuation coefficient (LAC) for the germinate glasses is in the order of 0.680-0.707 cm−1 and this is reported at 0.284 MeV, whereas the minimum LAC is observed at 1.33 MeV and varied between 0.159- 0.166 cm−1 . An increase in the LAC is found for these glasses due to the addition of Cr2O3, and the glasses coded as C5 (with 0.5 mol% of Cr2O3) has the highest LAC. The half value layer (HVL) of the selected glasses with different contents of Cr2O3 is investigated, and the results demonstrated that the HVL is small at low energies and ranging from 0.98-1.02 cm at 0.284 MeV and from 1.328-1.383 cm at 0.347 MeV. The maximum HVL is observed at 1.33 MeV and equal to 4.175 cm for C5 and 4.352 cm for C1. The tenth value layer (TVL) values for the present glasses were reported, and the results showed that as the density increases from 3.07 to 3.2 g/cm³, the TVL decreases from 3.388 to 3.256 cm at 0.284 MeV, and from 13.413 to 12.868 cm at 1.173 MeV. [ABSTRACT FROM AUTHOR]

In this work, Tm3+ doped and Tm3+/Ho3+ co-doped germanate glasses with various TiO 2 concentrations have been examined using optical spectroscopy. The broad emission bands corresponding to 3F 4 →3H 6 (1.8 μm) and 5I 7 →5I 8 (2 μm) transitions of thulium and holmium ions were registered, respectively. It was observed that the intensity of near-infrared emission bands significantly changes with increasing titanium oxide content in the glass composition. Furthermore, the energy transfer process from Tm3+ to Ho3+ ions in studied glass systems was confirmed and discussed. The dependence of spectroscopic parameters like full width at half maximum (FWHM) and energy transfer efficiency (η ET) on increased TiO 2 concentration in glass host was established. [ABSTRACT FROM AUTHOR]

The full-spectrum phosphors are key components for improving the light quality of phosphor-converted white light-emitting diodes (pc-WLEDs). In this work, a novel germanate glass-ceramic (GC) doped with Mn2+ was developed to achieve full-spectrum white light emission deriving from the defective Zn 2 GeO 4 crystalline phase and Mn2+ with multisite occupancy. The defective Zn 2 GeO 4 is crystallized in situ from the well-designed precursor germanate glass by a controllable heat treatment. The energy states of intrinsic defects, including oxygen and zinc vacancies and interstitial zinc and oxygen of Zn 2 GeO 4 in GC, have been studied by first-principles calculations. The luminescence property and the energy transfer mechanism between the defect states and Mn2+ ions in the GC material was proposed. Under the UV excitation, the luminescence property can be tuned by adjusting the distribution of Mn2+ ions in between the glassy and crystalline phases. The correlated color temperature (CCT) and color rendering index (CRI) of the UV-excited full-spectrum white light emission can be tuned over a wide range. This combinatorial strategy of intrinsic defects and multisite ion doping for full-spectrum white light emission in GC, which overcomes the limitation of conventional discontinuous white light emitting materials that emit singly from doping ions, has shown good potential for application in pc-WLEDs. [ABSTRACT FROM AUTHOR]

We prepared novel barium germanium (BaO–GeO 2) glass samples with varying BaO concentrations and investigated their physical and optical properties. We analyzed the refractive indices, glass transition temperatures (T g s), molar volumes, and optical band gaps of the samples, which were measured and plotted against their BaO concentrations. The results showed that refractive indices, T g s, molar volumes, and coefficients of thermal expansion increased with BaO concentration. Raman spectra showed structural network modifications and typical Germanium glass bands. The band at ∼ 529 cm−1 was assigned to vibration bonds of Ge(4)-O-Ge(4), and that at ∼ 823 cm−1 was attributed to stretching vibration of non-bridging oxygen (NBO) atoms. [ABSTRACT FROM AUTHOR]

In this work we studied the radiation shielding features of Li2O-Sb2O3-PbO-GeO2-Cr2O3 glass systems at different energies ranging from 0.284 to 1.33 MeV. The maximum linear attenuation coefficient (LAC) for the germinate glasses is in the order of 0.680−0.707 cm−1 and this is reported at 0.284 MeV, whereas the minimum LAC is observed at 1.33 MeV and varied between 0.159−0.166 cm−1 . An increase in the LAC is found for these glasses due to the addition of Cr2O3, and the glasses coded as C5 (with 0.5 mol% of Cr2O3) has the highest LAC. The half value layer (HVL) of the selected glasses with different contents of Cr2O3 is investigated, and the results demonstrated that the HVL is small at low energies and ranging from 0.98−1.02 cm at 0.284 MeV and from 1.328−1.383 cm at 0.347 MeV. The maximum HVL is observed at 1.33 MeV and equal to 4.175 cm for C5 and 4.352 cm for C1. The tenth value layer (TVL) values for the present glasses were reported, and the results showed that as the density increases from 3.07 to 3.2 g/cm³, the TVL decreases from 3.388 to 3.256 cm at 0.284 MeV, and from 13.413 to 12.868 cm at 1.173 MeV. [ABSTRACT FROM AUTHOR]

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others. [ABSTRACT FROM AUTHOR]

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Germanium selenide glasses of compositions spanning the whole glass-formation range are aged at room temperature for up to 20 years. A prominent enthalpy relaxation process is observed in all glasses, and its structural origin is analyzed by Raman spectroscopy. The structural relaxation is manifested in the Raman spectra as a decrease in the ratio of edge- to corner-sharing GeSe4/2 tetrahedral units. This structural evolution can be explained in terms of configurational entropy and density changes. Changes in Raman features and enthalpy follow an identical stretched exponential relaxation function characteristic of aging in glasses. The compositional dependence of enthalpy relaxation after 20 years is in agreement with kinetic considerations based on the glass transition temperature of each glass. The relaxation behavior and heat capacity curves are consistent with standard glass relaxation models for all compositions. These results indicate that the non-reversing enthalpy obtained by modulated differential scanning calorimetry (MDSC), which suggests the existence of non-aging glasses, is not a reliable measure of the ability of a glass to relax. Instead, it is suggested that an interpretation of MDSC data in terms of complex heat capacity provides a more complete and reliable assessment of the relaxation properties of glasses. [ABSTRACT FROM AUTHOR]

Bismuth-germanate glasses, which are well known as a promising active medium for broadband near-infrared spectral range fiber lasers and as an initial matrix for nonlinear optical glass ceramics, have been synthesized in a 5–50 mol% Bi2O3 wide concentration range. Their structural and physical characteristics were studied by Raman and FT-IR spectroscopy, differential scanning calorimetry, X-ray diffraction, optical, and luminescence methods. It has been found that the main structural units of glasses are [BiO6] and [GeO4]. The growth in bismuth oxide content resulted in an increase in density and refractive index. The spectral and luminescent properties of glasses strongly depended on the amount of bismuth active centers. The maximum intensity of IR luminescence has been achieved for the 5Bi2O3-95GeO2 sample. The heat treatment of glasses resulted in the formation of several crystalline phases, the structure and amount of which depended on the initial glass composition. The main phases were non-linear Bi2GeO5 and scintillating Bi4Ge3O12. Comparing with the previous papers dealing with bismuth and germanium oxide-based glasses, we enlarge the range of Bi2O3 concentration up to 50 mol% and decrease the synthesis temperature from 1300 to 1100 °C. [ABSTRACT FROM AUTHOR]

We report on direct femtosecond laser writing in zinc barium gallo-germanate glasses. A combination of spectroscopic techniques allows to progress in the understanding of the mechanisms taking place depending on the energy. In the first regime (type I, isotropic local index change) up to 0.5 µJ, the main occurrence is the generation of charge traps inspected by luminescence, together with separation of charges detected by polarized second harmonic generation measurements. At higher pulse energies notably at the threshold corresponding to 0.8 µJ or in the second regime (type II modifications corresponding to nanograting formation energy domain), the main occurrence is a chemical change and re-organization of the network evidenced by the appearance of molecular O2 seen in the Raman spectra. In addition, the polarization dependence of the second harmonic generation in type II indicates that the organization of nanogratings may be perturbed by the laser-imprinted electric field. [ABSTRACT FROM AUTHOR]

Bismuth (Bi)‐doped glasses with broadband near‐infrared (NIR) emission have been drawing increasing interest due to their potential applications in tunable fiber lasers and broadband optical amplifiers. Yet, the implementation of highly efficient and ultra‐broadband Bi NIR emission covering the whole telecommunication window remains a daunting challenge. Here, via a metal reduction strategy to simultaneously create a chemically reductive environment during glass melting and enhance the local network rigidity, a super broadband (FWHM ≈ 600 nm) NIR emission covering the entire telecommunications window with greatly enhanced intensity was achieved in Bi‐doped germanate glasses. More importantly, due to the excellent thermal stability, the super broadband Bi NIR emission can be well retained after the glass was drawn into an optical fiber. Furthermore, the transmission loss of 0.066 dB/cm at 1310 nm and an obvious broadband amplified spontaneous emission spectrum spanning a range of 1000–1600 nm were observed in this fiber. This work can strengthen our comprehension of the complicated Bi NIR luminescence behaviors and offer a feasible and universal way to fabricate tunable fiber lasers and broadband optical amplifiers based on Bi‐doped multicomponent glasses. [ABSTRACT FROM AUTHOR]

Bismuth(Bi)‐doped photonic materials with broadband near‐infrared luminescence can be used in applications such as high‐capacity fiber communication, fiber laser, and biological imaging. The scalable fabrication of Bi‐doped fibers with high dopant solubility, high optical activity, and broadband optical response still remains a significant challenge. In this study, the comprehensive studies on the physical, chemical, mechanical, and optical responses of a Bi‐doped glass system are performed and a Bi‐doped germanate multicomponent glass system is proposed to be the promising candidate. The deactivation mechanism of Bi in a glass matrix is investigated and prevented by controlling the fiber drawing. In addition, a Bi‐doped multicomponent germanate glass fiber with a high level of Bi doping is successfully constructed. Finally, a principle compact fiber amplifier device is fabricated for broadband optical amplification. This device can be potentially used for increasing the capacity of telecommunication systems. [ABSTRACT FROM AUTHOR]

Recent studies of potassium niobium germanate glasses have concentrated on the production of transparent glass-ceramics for nonlinear optical devices. Since very little is known about the properties of these glasses and their dependence on composition, the density, molar volume, glass transformation temperature (Tg) and electrical conductivity have been determined for two series of potassium niobium germanate glasses lying on lines of constant Nb2O5 to K2O concentrations. Replacement of GeO2 by Nb2O5 has little effect on the location of anomalies in the density and Tg, but the anomaly in the molar volume disappears. Niobium oxide decreases the density of these glasses at low concentrations, but increases the density at higher concentrations. The Tg increases by 50 to 100 K as Nb2O5 replaces GeO2. The electrical conductivity decreases at all K2O concentrations as GeO2 is replaced by Nb2O5. A structural model is proposed where the Ge--O--Ge network is progressively replaced by a Nb--O--Nb network with increasing Nb2O5 content. [ABSTRACT FROM AUTHOR]

We report an unexpected pulse repetition rate effect on ultrafast-laser modification of sodium germanate glass with the composition 22Na2O 78GeO2. While at a lower pulse repetition rate (~≤250 kHz), the inscription of nanogratings possessing form birefringence is observed under series of 105–106 pulses, a higher pulse repetition rate launches peripheral microcrystallization with precipitation of the Na2Ge4O9 phase around the laser-exposed area due to the thermal effect of femtosecond pulses via cumulative heating. Depending on the pulse energy, the repetition rate ranges corresponding to nanograting formation and microcrystallization can overlap or be separated from each other. Regardless of crystallization, the unusual growth of optical retardance in the nanogratings with the pulse repetition rate starting from a certain threshold has been revealed instead of a gradual decrease in retardance with the pulse repetition rate earlier reported for some other glasses. The repetition rate threshold of the retardance growth is shown to be inversely related to the pulse energy and to vary from ~70 to 200 kHz in the studied energy range. This effect can be presumably assigned to the chemical composition shift due to the thermal diffusion of sodium cations occurring at higher pulse repetition rates when the thermal effect of the ultrashort laser pulses becomes noticeable. [ABSTRACT FROM AUTHOR]

This work investigates the optical properties of Yb3+ ions doped GeO2-PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices. [ABSTRACT FROM AUTHOR]

In recent years, 3D printing glass optics has gained massive attention in industry and academia since glass could be an ideal material to make optical elements, including the lens. However, the limitation of materials and printing methods has prevented 3D printing glass optics progress. Therefore, we have developed a novel printing strategy for germanate glass printing instead of pure silica. Moreover, compared with traditional multi-component quartz glass, germanate glass has unmatched advantages for its mid-infrared (MIR) transparency and outstanding visible light imaging performance. Furthermore, compared with non-oxide glass (fluoride glass and chalcogenide glass), germanate glass has much better mechanical, physical, and chemical properties and a high refractive index. Germanate glass has been widely applied in remote sensing, ranging, environmental detection, and biomedical detection. However, it is difficult to shape, cast, polish, and grind for optical and photonics applications such as imaging optics and laser-collimation optics. These drawbacks have made germanate glass inaccessible to complex optical elements and greatly increased their cost. In this report, we use germanate glass fibers with a diameter of 125 µm based on fiber-fed laser heating technology to fabricate an mm-size optical application. In this paper, we combine the fiber-fed laser heating technology with an optimized temperature control process to manufacture high-precision optical elements. Germanate glass optics can be printed with excellent visible light and IR transparency and a smooth surface with roughness under 4 nm. By optimizing the layer-by-layer 3D printing process and the thermal feedback in the printing process, we avoid cracks and minimize surface deformation. This work shows the possibility of the mm-size glass optical elements 3D printing and widens its application for IR optics. [ABSTRACT FROM AUTHOR]

Modified barium gallo-germanate glass hosts are still worthy of attention in studying structure–property relationships. In this work, two different series of glass systems based on (60-x)GeO2-xTiO2-30BaO-10Ga2O3 and (60-x)GeO2-xB2O3-30BaO-10Ga2O3 (x = 10, 30, 50 mol%) were synthesized, and their properties were studied using spectroscopic techniques. X-ray diffraction (XRD) patterns revealed that all fabricated glasses were fully amorphous material. The absorption edge shifted toward the longer wavelengths with a gradual substitution of GeO2. The spectroscopic assignments of titanium ions were performed with excitation and emission spectra compared to the additional sample containing an extremely low content of TiO2 (0.005 mol%). On the basis of Raman and FT-IR investigations, it was found that increasing the TiO2 content caused a destructive effect on the GeO4 and GeO6 structural units. The Raman spectra of a sample containing a predominantly TiO2 (50 mol%) proved that the band was located near 650 cm−1, which corresponded to the stretching vibration of Ti-O in TiO6 unit. The deconvoluted IR results showed that the germanate glass network consisted of the coexistence of two BO3 and BO4 structural groups. Based on the experimental investigations, we concluded that the developed materials are a promising candidate for use as novel glass host matrices for doping rare-earth and/or transition metal ions. [ABSTRACT FROM AUTHOR]

Due to the excellent infrared transparency, low phonon energy, and high rare‐earth solubility, germanate laser glass has attracted much attention in mid‐infrared fiber lasers for potential coherent laser radar systems, optical detection, remote sensing, and laser surgery. However, radiation‐induce darkening often occurs in fiber lasers that operate in radiation environment. Here, we report a useful strategy to improve the radiation resistance by adding multivalence Bi ions and discuss its radiation resistance mechanism. In order to study the effect of valence states on the radiation resistance of barium gallo‐germanate glass, we adjust the valence states of Bi ions by heat treatment, the potential mechanism of which is discussed in detail based on the absorption, photoluminescence (PL), and Raman spectra. The absorption, electron paramagnetic resonance, and photoluminescence spectra have proved the interconversion of Bi ions between low and high valence, which inhibits the formation of Ge‐related electron center (GEC) and non‐bridging oxygen hole center defects in the irradiation process. In addition, the Bi3+ content increased by heat treatment is beneficial to serve as electron‐trapping centers in γ‐ray irradiation, thus further reducing the formation of GEC. This study provides a simple method to achieve Bi valence regulation, so as to improve the radiation resistance. [ABSTRACT FROM AUTHOR]

Germanate-based oxyfluoride transparent glass-ceramic functionalized by Tm3+:Ca 2 YbF 7 nanocrystals was newly developed. The tremendously enhanced upconversion emission of 3F 2,3 energy levels by in situ crystallization was extremely beneficial for constructing optical thermometry involving the indirect thermally coupled energy levels (1G 4 and 3F 2,3) of Tm3+ ions. Utilizing the fluorescence intensity ratio technique, the thermometry potentials of PG and GC8 were systematically evaluated based on the emissions from 3F 2,3 and 1G 4 energy levels. The relative and absolute sensitivities, thermometry resolutions, and repeatabilities were superior to many reported materials. This work provides an avenue for precipitating ternary fluoride nanocrystals containing rare earths in germanate-based oxyfluoride glass, and proposes a promising way to achieve high performance optical thermometry based on the emissions from widely spaced energy levels. [ABSTRACT FROM AUTHOR]

In recent years, the use of optical methods for temperature measurements has been attracting increased attention. High-performance miniature sensors can be based on glass microspheres with whispering gallery modes (WGMs), as their resonant frequencies shift in response to the ambient parameter variations. In this work, we present a systematic comprehensive numerical analysis of temperature microsensors with a realistic design based on standard silica fibers, as well as commercially available special soft glass fibers (GeO2, tellurite, As2S3, and As2Se3). Possible experimental implementation and some practical recommendations are discussed in detail. We developed a realistic numerical model that takes into account the spectral and temperature dependence of basic glass characteristics in a wide parameter range. To the best of our knowledge, spherical temperature microsensors based on the majority of the considered glass fibers have been investigated for the first time. The highest sensitivity dλ/dT was obtained for the chalcogenide As2Se3 and As2S3 microspheres: for measurements at room temperature conditions at a wavelength of λ = 1.55 μm, it was as high as 57 pm/K and 36 pm/K, correspondingly, which is several times larger than for common silica glass (9.4 pm/K). Importantly, dλ/dT was almost independent of microresonator size, WGM polarization and structure; this is a practically crucial feature showing the robustness of the sensing devices of the proposed design. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the GeO2:TiO2 molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic 1D2 → 3H4 (red), 5S2, 5F4 → 5I8 (green), and 1D2 → 3F4 (blue) transitions of Pr3+, Ho3+, and Tm3+ ions in systems modified by TiO2 were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr3+ and Ho3+ ions increases, whereas, for Tm3+-doped systems, luminescence quenching with increasing content of TiO2 was observed. Based on Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO2:TiO2 molar ratio. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO2 content. Moreover, it can be stated that germanate-based glass systems modified by TiO2 can be used for optoelectronics in RGB technology as red (Pr3+), green (Ho3+), and blue (Tm3+) emitters. [ABSTRACT FROM AUTHOR]

Pr3+ doped high density germanate glasses were prepared by the melt-quenching method. The physical and luminescent properties were investigated. The glass containing BaF 2 represented maximum phonon energy of 810 cm−1, and the glass density was greater than 6 g/cm3. The glass exhibited good radiation resistance under 2 h of X-ray irradiation. Intense blue, green emissions and weak red emissions were observed when the glass was excited by X-ray, and the blue fluorescence lifetimes were in the range of 9.15–12.59 μs The results show that Pr3+ doped germanate glass could be a potential scintillating material in the field of X-ray detection for fast events. [ABSTRACT FROM AUTHOR]

• Germanium-based glass materials were prepared by employing a high-temperature melting method, and then graphene-glass composite anode materials were prepared by ball-milling technique. • The prepared composite glass anode has a stable structure and shows high capacity performance, the discharge/charge specific capacity reached 1108.2/1098.6 mAh g-1 after 450 cycles at a current density of 500 mA g-1. • The results show that the introduction of graphene provides a good layer structure to provide a buffer space for dealing with the internal stresses generated by the embedded lithium ions in the alloying reaction, as well as reducing the volume expansion of the germanium-based glass anode during cycling. The performance of a lithium-ion battery (LIB) is largely contingent upon its anode material. At present, germanium-based anode materials are of interest due to their high theoretical capacity, but there are fewer studies on germanium-based glass anode materials. In this work, graphene mixed germanium-based glass composite material was fabricated utilizing the ball-milling technique. The addition of graphene greatly reduces the charge transfer resistance of the germanium-based glass anode during cycling. Meanwhile, the composite anode exhibited a high specific capacity of 1101.5 mAh g-1 during the first discharge cycle, and the discharge/charge specific capacity was still as high as 1108.2/1098.6 mAh g-1 after 450 cycles at a current density of 500 mA g-1. Moreover, at a high current of 2 A g-1, the composite anode still maintains a high discharge specific capacity of 437.2 mAh g-1, and there is no obvious swelling on the surface, showing excellent stability. It is hoped that the current research endeavor may offer a fresh direction for future studies aimed at optimizing germanium-based glass anode materials. [ABSTRACT FROM AUTHOR]

Glasses in the system BaO – La 2 O 3 – Ga 2 O 3 – GeO 2 and Langasite crystalline phases with the same stoichiometry have been studied considering the possible use of these glasses for laser-induced space-selective growth of crystalline architectures in the glass compositions. For better understanding of mechanisms involved in such controlled crystallization process, crystalline and glass compounds with same stoichiometry and different La/Ba ratios have been synthesized to compare their local structure. Solid-state Nuclear Magnetic Resonance evidence 4- and 5-coordinated gallium units in the glass matrix, denying unambiguously the formation of 6-coordinated gallium sites observed in crystalline phases. Moreover vibrational spectroscopies suggest a link between a 3D network formed by 4- and 5-coordinated gallium, connected to each other and to 4- coordinated Q4 and Q3 germanium units in the glass and their congruent crystallization. The transition from 4- and 5-coordinated gallium to 6-coordinated gallium sites observed in Langasite crystalline phases remains not still elucidated. [ABSTRACT FROM AUTHOR]

Red-emitting perovskite quantum dots (QDs) have significant potential for application in optoelectronic devices. However, their application is hindered by preparation challenges and low photoluminescence quantum yield (PLQY). In this study, CsPbBrI 2 red-emitting QDs with a PLQY of up to 58.73 % were synthesized in germanium borate glass. The experimental results indicated that the addition of Nb5+ can not only partially replace the Pb2+ sites but also passivate halogen defects in QDs, enhance radiative transitions, and significantly improve the lattice ordering of CsPbBrI 2 QDs glass. Additionally, the incorporation of Nb 2 O 5 supplies free oxygen, facilitating the conversion of [BO 4 ] to [BO 3 ] in the glass network, which results in a looser structure conducive to crystallization. Moreover, the Nb5+-doped CsPbBrI 2 QDs glass demonstrated excellent hydrothermal stability. The QDs glass exhibiting the highest luminescent performance was subsequently combined with an InGaN blue chip to create a WLED with a color rendering index (CRI) of 82.7. This study offers an innovative methodology for synthesizing perovskite QDs glass materials with enhanced red emission efficiency through transition metal doping, highlighting their significant potential for practical applications in WLEDs. • Nb5+ modified red-emitting CsPbBrI 2 quantum dots glass with PLQY up to 58.73 %. • Nb5+ can partially replace Pb2+ sites and passivate halogen defects in QDs. • Nb 2 O 5 converts [BO 4 ] to [BO 3 ], optimize the crystallization behavior of QDs. • The obtained glasses exhibit excellent water and thermal stability. • A WLED with a CRI of 82.7, CCT of 6495 K and LE of 72.82 lm/W is constructed. [ABSTRACT FROM AUTHOR]

The current investigation studied one of the high-density heavy metal oxides (Bi 2 O 3) having density = 8.9 g/cm³, which was utilized to improve structural and optical features of the B 2 O 3 –TeO 2 -GeO 2 -MgO glass system. Three high transparent glasses with a chemical formula of 35B 2 O 3 –20TeO 2 -10GeO 2 -35MgO-xBi 2 O 3 (x = 5, 10, and 15 mol %) were fabricated by melting at 1100 °C for 20 min and annealing at 400 °C for 5 h. X-ray diffraction measurements for the Bi5 sample, containing 5 mol % Bi 2 O 3 , were obtained at the range of 10°–80° to inspect the structural characteristics of the made glasses. Optical absorption was employed and recorded for Bi5, Bi10, and Bi15 samples at wavelength range 300–1000 nm to examine the optical properties, including optical band gap. Using Makishima and Mackenzie methods, the mechanical features of the glass samples were assessed. Nuclear library ENDF/B-VI.8 is coupled to the MCNP-5 code and is used to study and simulate the prepared Bi glass sample shielding parameters. The ionizing absorption properties for the prepared Bi5, Bi10, and Bi15 samples were found to be changed because of many circumstances like the photon energy (Eγ, MeV), and chemical compositions (Bi 2 O 3 content (mol. %). The increased layer thickness of glass between 25 and 200 mm enhances the RPE values at 0.6 MeV over the range of 16.31–50.93 % (Bi5 glass sample), 18.68–56.26 % (Bi10 glass sample), and 20.80–60.66 % (Bi15 glass sample). • Four glasses with composition of 35B 2 O 3 –20TeO 2 -10GeO 2 -35MgO-xBi 2 O 3 , (x = 5, 10, and 15 mol%) have been synthesized. • The melt-quenching-annealing process was employed in the synthesis of the glass system. • X-ray diffractometer confirms the amorphous structure of the glasses. • The RPE for all prepared glass samples reaches 100 % at 0.06 MeV. [ABSTRACT FROM AUTHOR]

In the present work, a group of four glass samples that have chemical composition of [(35-x) B 2 O 3 -20TeO 2 -10GeO 2 -35MgO-xLa 2 O 3 ] were x values varies from 2.5 to 10 all in mol percentage, which fabricated using ordinary melting then quenching technique. Many physical and mechanical have been measured and calculated like: density, packing density, internuclear distance (r i), oxygen packing density (OPD), oxygen molar volume (OMV), dissociation energy (G t), packing density (V t), Poisson ratio (σ), fractal bond connectivity (d), elastic modulus. The behavior of the La10 was examined using XRD in the range of 10–80°. The UV–visible spectrum of absorption of the La2.5, La5, La7.5, and La10 glasses were measured. Several optical parameters have been calculated and extracted including the cutoff wavelength, Urbach's energy (E U), dielectric constant (ε), refractive index (n), molar refraction (R M), reflection loss (R L), molar electron polarizability (α M), Optical transmission (T), Optical basicity (Λ), and Metallization criteria (M). Various noticeable bands vibration of boron units structural besides the modes of vibration of that effected by adding metal cations were studied using FTIR to analyze different structure groups like: BO 3 triangles, BO 4 pyramids, tetragonal TeO 4 pyramids, and trigonal TeO 3 pyramids. Using Monte Carlo simulation, the MAC of glass materials was evaluated in the current work. Various radiation shielding parameters were investigated at low and high energies. [ABSTRACT FROM AUTHOR]

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.

Kowalska et al. [[17]] report near-IR luminescence properties of selected rare-Earth ions (Er SP 3+ sp , Pr SP 3+ sp , Ho SP 3+ sp , Tm SP 3+ sp ) in titanate-germanate glasses under excitation of Yb SP 3+ sp . 35683100 17 Kowalska K., Kuwik M., Pisarska J., Pisarski W.A. Near-IR luminescence of rare-earth ions (Er3+, Pr3+, Ho3+, Tm3+) in titanate-germanate glasses under excitation of Yb3+. Rare-Earth ions, as optically active ions, are usually incorporated into the crystalline phases. [Extracted from the article]

The writing of continuous crystalline lines with an oriented structure, which were formed by the ferroelectric phase of Li2Ge7O15, was demonstrated under the action of a focused femtosecond laser beam in the interior bulk of glass with molar composition 20% Li2O and 80% GeO2. An unexpected difference was found between the crystalline phases precipitated in this glass under the action of a laser beam and on heat treatment in a furnace. The results obtained are of interest for devising crystalline channel waveguides in lithium germanate glass. [ABSTRACT FROM AUTHOR]