Li2O Bi2O3 Research Articles

NLO and white light emission in AuNPs reinforced Li2O–Bi2O3–B2O3–P2O5 glasses: Role of surface plasmonic resonance AuNPs

Significant optical nonlinearities in amorphous nanocomposites are essential for developing advanced communications and photonic devices. In this regard, the borate glasses are considered substantial and readily available commercial hosts. The present work demonstrates the white light emission and decay properties in lithium bismuth boro-phosphate glasses reinforced with gold nanoparticles (AuNPs) prepared via melting and quenching technique. Also, their non-linear optical properties are evaluated in the present study. Numerous characterization methods were used to extensively examine the produced glasses, including XRD, HR-TEM, FTIR, XPS, MAS-NMR, DSC, UV–Visible, Photoluminescence, and Z-scan techniques. Following the addition of AuNPs into the glass matrix, an increase in the refractive index and density of the glasses was observed. The amorphous features of the glass sample are disclosed by XRD examination, and DSC research demonstrates the thermal stability of the glasses after the addition of AuNPs, as shown by the rise in Tg values from 459 °C to 486 °C. HR-TEM results reveal the presence of Au metal nanoparticles having a cubic crystal structure with an average size of 14 nm, while XPS analysis shows that the valence of Au is 0, i.e. Au0 or, in other words, the metallic nature of gold in glasses. FTIR, MAS-NMR, and UV–Visible spectral studies demonstrate the substantial modifications in the physical, structural, and optical properties brought about by incorporating AuNPs into the glass matrix. The PL spectra of glasses containing AuNPs show three distinct, sharp emissions at 494, 611, and 738 nm, out of which the blue emission (494 nm) is found to be predominant and has an overall emission in the region of yellow on the CIE diagram with an average lifetime of 12.23 μs. Glasses containing AuNPs have a white light correlated colour temperature (CCT) of 5129 K and CIE chromaticity (x, y) coordinates of (0.346, 0.413). Additionally, we utilized a Z-scan technique to measure the nonlinear absorption coefficient and nonlinear refractive index. Our experimental data show that the values obtained are consistent with the theoretical closed and open aperture values. Based on our findings, it appears that the glasses we prepared have the potential to be utilized in optical switching applications.

Lowering the sintering temperature of Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> electrolyte for co-fired all-solid-state batteries via partial Bi substitution and precise control of compositional deviation

Li7La3Zr2O12 (LLZ) has great potential as a solid electrolyte for co-fired all-solid-state Li-ion secondary batteries. However, to realise a solid-state battery using LLZ, the sintering temperature of LLZ should be reduced to one that can suppress the formation of a high-resistance reaction layer at the interface between LLZ and the electrode. In this study, we demonstrate an effective method for reducing the sintering temperature of Li6La3ZrTaO12 by combining partial Bi-substitution for Ta and precise control of the compositional deviation. The intentional tuning of the La deficiency in Li6La3ZrTa0.8Bi0.2O12 (LLZTB0.2) promoted the formation of a liquid phase based on Li2O–Bi2O3 at the grain boundary, resulting in its densification at 775 °C. Furthermore, we fabricated a co-fired all-solid-state half-cell based on an LLZTB0.2 electrolyte attached to a LiCoO2 + LLZTB0.2 composite electrode and a half-cell operated at 60 °C. From these results, it was found that the proposed concept is effective in reducing the sintering temperature of LLZ and is applicable for co-firing an all-solid-state battery.

Single-mode tellurite optical fiber for temperature measurement based on the self-phase modulation effect.

In this paper, the self-phase modulation (SPM) effect in a double-cladding single-mode tellurite optical fiber (DC-SMTOF) was exploited for temperature sensing. The DC-SMTOF was fabricated based on a TeO2-ZnO-Li2O-Bi2O3 (TZLB) glass material that has a thermo-optical coefficient as high as -16.4×10-6/°C. The temperature sensing performance was evaluated by detecting the 3-dB bandwidth of the SPM spectra with the variation of temperature at different pump wavelength and different average pump power. The temperature sensitivity was obtained to be -2.971 nm/°C with a resolution of 0.0168°C. Both simulation and experiment confirmed that a longer pump wavelength and higher average pump power will result in a higher temperature sensitivity. To the best of our knowledge, this is the first study concerning SPM-based temperature sensing in a tellurite optical fiber. The proposed temperature sensor has a compact structure, and it can realize temperature sensing of high sensitivity without any fiber modification. This work opens the road toward explorations of a novel temperature sensing technology combined with soft glass fibers and nonlinear phenomenon, and is expected to deepen our understanding in the application of these complex nonlinear phenomena.

Experimental investigation of polarization modulation instability in a double-clad single-mode tellurite optical fiber

A double-clad single-mode tellurite optical fiber (DC-SMTOF) with a loss of 0.5 dB/m @1545.1 nm was fabricated based on the TeO2–ZnO–Li2O–Bi2O3 (TZLB) material. During the fiber drawing process, a low level of residual birefringence was produced, which gave a chance for the investigation of the polarization modulation instability (PMI). With a nanosecond laser operated at 1545.1 nm as the pump source, the PMI effect in the DC-SMTOF was investigated using different fiber length and different average pump power. This investigation of the PMI generation in non-silica optical fibers may provide guidance for the generation of the highly repetitive optical pulse train.

Structural, optical, and shielding investigations of TeO2–GeO2–ZnO–Li2O–Bi2O3 glass system for radiation protection applications

Glass gained much attention to be utilized in various applications, for this reason different kinds of glass compositions was the subject of investigation. In this work, we successfully fabricated a series of tellurite–germanate glasses with a composition of (70-x)TeO2–10GeO2–10ZnO–10Li2O–xBi2O3, where x = 0, 5, 10 and 15 (all in mol%). Ordinary melt-quenching was used to synthesize the mentioned glass series with 975 °C as a melting temperature for 30 min and 300 °C for annealing to release the internal stress. To study the structural properties of these glasses, X-ray diffraction (XRD) was used to confirm the glassy structure of these glasses. Regarding that, XRD profiles were recorded in ranges between 10° and 80° for all samples. Moreover, FTIR was employed to study the functional groups of all elements, which were used in the composition with the range of 4000–400 cm−1. Optical absorption was used to investigate the cutoff wavelength and optical band gap. Optical absorption was measured at the range of 200–800 nm. The variation of the attenuation properties for the tested tellurite–germanate glasses has been investigated using WinXcom software for photon energy ranges between 0.015 and 15 MeV. The examined attenuation properties include linear and mass attenuation coefficients, half value layer and mean free path, and effective atomic number of the radiation shielding glass. The present results suggest the utilization of the new prepared glass samples in radiation shielding applications.

Structural and photoluminescence investigations of Cr3+ mixed Li2O—Bi2O3—ZrO2—SiO2 glass ceramics for optoelectronic device application

Chromium oxide mixed Li2O―Bi2O3―ZrO2―SiO2 (Cr3+:LBZS) glasses were crystallized by heat treatment. Structural (X-ray diffraction, surface morphology, energy dispersion, DTA, FT-IR and Raman) and spectroscopic (optical absorption and luminescence), of these Cr3+:LBZS glass ceramics were studied. XRD pattern of Cr3+: LBZS glass ceramic samples exhibited distinct crystalline peaks. SEM images of the Cr3+: LBZS glass ceramic materials have revealed well identified and distributed crystals of reformed size. The glass transition (Tg) and various crystallization temperatures (Tc1), (Tc2) and (Tc3) of these ceramics were identified by DTA analysis. The shift in the wavenumbers of different symmetrical and asymmetrical band positions of these glass ceramics were analysed by FT-IR and Raman studies. The optical bandgap (Eo), CFSE (Dq) and nephelauxetic ratio (β) were calculated. Photoluminescence properties were also investigated.

First assessment of Li2O–Bi2O3 ceramic oxides for high temperature carbon dioxide capture

The capacity to capture CO2 was determined in several stoichiometric compositions in the Li2O–Bi2O3 system. The compounds (Li7BiO6, Li5BiO5, Li3BiO4 and LiBiO2 phases) were synthesized via solid-state reaction and characterized by X-ray diffraction, scanning electron microscopy and N2 adsorption techniques. The samples were heat-treated at temperatures from 40 to 750°C under the CO2 atmosphere to evaluate the carbonate formation, which is indicative of the capacity of CO2 capture. Moreover, Li7BiO6 shows an excellent CO2 capture capacity of 7.1mmol/g, which is considerably higher than those of other previously reported ceramics. Li7BiO6 is able to react with CO2 from 240°C to approximately 660°C showing a high kinetic reaction even at CO2 partial pressure values as low as 0.05.

Low temperature sintering of high permittivity BaTiO3 based X8R ceramics doped with Li2O–Bi2O3–B2O3 frit

BaTiO3 ceramics doped with 3wt% K0.5Na0.5NbO3 content and different Li2O–Bi2O3–B2O3 frit as the sintering aids were prepared by the conventional solid state ceramic route. The effects of the Li2O–Bi2O3–B2O3 frit on the phase composition, microstructure and dielectric properties of BaTiO3 ceramics were investigated. Results show that the BaTiO3 pellet has pure tetragonal crystal structure. And the dielectric ceramic with high permittivity of 5585 and excellent densification were obtained at a sintering temperature of 980°C, meeting X8R specifications. The results also suggest that the developed BaTiO3 based X8R ceramics may serve as a promising candidate for fabricating cheap multilayer capacitors with base metal as inner electrode.

Study of elastic moduli of lithium borobismuthate glasses using ultrasonic technique

Ultrasonic studies on x B2O325 Li2O(75−x) Bi2O3, (0≤x≤75mol%) glasses have been carried out. The elastic moduli of glasses have been investigated using ultrasonic velocity measurements at 4MHz. The results revealed an increase of the ultrasonic velocity and Debye temperature with the increase of the B2O3 content which was attributed to the increase in the packing density, the local contraction of the network around the Bi and Li cations and the increase of the number of bonds per unit volume. Also, the increase of the elastic moduli with the increase in the B2O3 content is affected with the increase in the dissociation energy, the average cross-link density, the increase in the number of bridging oxygen atoms, and the substitution of high bond strength BO with low bond strength BiO. The optical properties such as the refractive index, the energy gap and the optical polarizability were evaluated from the values of the elastic moduli. It was observed that as the bulk modulus increases, the optical energy gap increases and both the refractive index and the optical basicity decrease.

Low temperature sintering of .BETA.-spodumene ceramics with low thermal expansion using Li2O-Bi2O3 as a sintering additive

Low temperature sintering of β-spodumene ceramics with low coefficient of thermal expansion (CTE) was attained using Li2O–Bi2O3 sintering additive. High purity β-spodumene could be synthesized at 1150°C using high purity and fine amorphous silica, γ-alumina and lithium carbonate powder mixture via the solid state reaction route. The mixture was calcined at 800°C, pulverized, compacted, and sintered with or without the sintering additive at 800–1350°C for 2 h. The relative density reached 95% for the sample sintered with 3 mass % of Li2O–Bi2O3 additive at 1050°C for 2 h. As a result, sintering temperature could be lowered about 200°C by adding the sintering additive, compared with the sintering temperature previously reported. The flexural strength of the sample sintered with 3% of Li2O–Bi2O3 additive at 1050°C for 2 h was 118 MPa. Its CTE (from R.T. to 800°C) was 0.2 × 10−6/K. Its dielectric constant was 8.2 with loss tangent of 1.4%.

Low temperature sintering of .ALPHA.-cordierite ceramics with low thermal expansion using Li2O-Bi2O3 as a sintering additive

Low temperature sintering of α-cordierite ceramics with low coefficient of thermal expansion was attained using Li2O–Bi2O3 sintering additive. High purity α-cordierite could be synthesized at 1270°C using high purity and fine amorphous silica, α-alumina and magnesium oxide powder mixture via the solid state reaction route. The mixture was calcined at 1240°C, pulverized, compacted, and at first sintered without sintering additive. High density and outstanding characteristics cordierite ceramics was obtained. However, sintering temperature reached 1430°C, which was extremely high. By adding 3 mass % of the additive, the sintering temperature could be lowered from 1430 to 1050°C. Its relative density reached 97%, its flexural strength, however, decreased from 243 to 120 MPa. Its thermal expansion coefficient (from R.T. to 800°C) decreased slightly from 1.8 × 10−6/K to 1.6 × 10−6/K. Its dielectric constant increased slightly from 4.9 to 5.2 accompanied with considerable increase in loss tangent from 1.3 × 10−4 to 6.1 × 10−4 at 14 GHz, which were, however, low enough at this high frequency range. These results indicated that the addition of Li2O–Bi2O3 sintering additive had negligibly small effects on the properties of the sintered sample except mechanical properties and the loss tangent. These properties were found more excellent or at least comparable compared with the best properties previously reported and suitable for substrate materials on micro-electronic applications.

Microwave Dielectric Ceramics in Li2O–Bi2O3–MoO3 System with Ultra‐Low Sintering Temperatures

A series of compounds in the Li2O–Bi2O3–MoO3 ternary system were investigated with regard to the preparation, phase composition, microwave dielectric properties, and chemical compatibility with silver (Ag) and aluminum (Al) electrodes. All the ceramics in this work have sintering temperatures lower than 750°C. The sintering behaviors and microwave dielectric properties of three single phases Li2MoO4, (Li0.5Bi0.5)MoO4, and Li8Bi2Mo7O28 bulk ceramics, were of particular focus in this investigation. The Li2MoO4 ceramic can be sintered to a high density at 540°C/2 h with a relative permittivity ∼5.5, a Q×f value of 46 000 GHz, and a temperature coefficient of resonant frequency (TCF) of ∼−160 ppm/°C. The (Li0.5Bi0.5)MoO4 ceramic has a scheelite structure and the largest relative permittivity of 44.4 among the ceramics studied in this work with a sintering temperature around 560°C, a Q×f value of 3200 GHz, and a large positive TCF of ∼+245 ppm/°C. The Li8Bi2Mo7O28 ceramic could be sintered at 540°C and has a relative permittivity of 13.6, a Q×f value of 8000 GHz, and a small negative TCF value of ∼−59 ppm/°C. From the X‐ray diffraction analysis of cofired ceramics, the Li2MoO4 ceramic does not react with either Ag or Al powders. The Li8Bi2Mo7O28 ceramic reacts with Ag but not with Al at its densification temperature. The (Li0.5Bi0.5)MoO4 ceramic was found to strongly react with Ag powder and to a limited extent with Al powders. From this study, the Li2O–Bi2O3–MoO3 ternary system has a number of attractive new materials with low sintering temperatures, high‐performing microwave dielectric properties, chemical compatibility with both Ag and Al metal electrodes, nontoxicity, and low‐cost constituents. All these materials can be included in the new field of ultra‐low‐temperature cofiring dielectrics for multilayer applications.

Use of CsCl to Enhance the Glass Stability Range of Tellurite Glasses for Er3+-Doped Optical Fiber Drawing

Tellurite glasses are important as a host of Er3+ ions because of their good solubility and because they present broadband optical gain compared with Er3+-doped silica, with the potential to increase the bandwidth of communication systems. However, the small glass stability range (GSR) of tellurite glasses compromises the quality of the optical fibers. We show that the addition of CsCl to tellurite glasses can increase their GSR, making it easier to draw good-quality optical fibers. CsCl acts like a network modifier in glass systems, weakening the network by forming Te–Cl bonds. We show that the thermal expansion coefficient mismatch is in the right direction for optical fiber fabrication purposes and that the Bi2O3 content can be used to control the refractive index of clad and core glasses. Single-mode and multi-mode Er3+-doped optical fibers were produced by the rod-in-tube method using highly homogeneous TeO2–ZnO–Li2O–Bi2O3–CsCl glasses.

Control of microwave dielectric properties of CaTiO3-based high-permittivity ceramics using additives

The effects of Li2O–Bi2O3–TiO2 (LBT) additions on the microwave dielectric properties of high-permittivity CaO–Sm2O3–Li2O–TiO2 (CSLT) ceramics have been investigated. Addition of LBT up to 10wt% simultaneously reduced the sintering temperature and improved the density of the sintered CSLT ceramics. Scanning electron microscope (SEM) analysis showed a secondary phase when up to 10wt% of LBT was added to CSLT, which disappeared at higher sintering temperatures. However, x-ray diffraction (XRD) analysis revealed that all the compositions had a distorted perovskite structure. By varying the amounts of LBT additions within 0.5–10wt% of the main component and the sintering temperature (1200–1400°C), a wide range of dielectric properties with permittivity in the range of 92–113, Qf>3000GHz, and TCf=±20ppm∕°C were obtained. For example, with 1.0wt% LBT additions sintered at 1400°C, εr=94.02, Qf=5970GHz, and TCf=6.8ppm∕°C; with 5.0wt% LBT additions sintered at 1350°C, εr=101.91, Qf=5050GHz, and TCf=0.4ppm∕°C; with 10.0wt% LBT additions sintered at 1250°C, εr=112.12, Qf=3560GHz, and TCf=1.0ppm∕°C. These combinations of advantages make LBT a very useful additive in developing a range of dielectric characteristics in CaO–Ln2O3–Li2O–TiO2 group of microwave dielectric ceramics.

Li+ ion dynamics in strontium bismuthate glasses

Ion transport in Li2O–Bi2O3–SrO glasses has been studied in the frequency range 10 Hz–2 MHz and in the temperature range263–483 K. The variation of the dc conductivity and the activation energy of these glasses withcomposition has been compared with those of bismuthate and lead bismuthate glasses. Thefrequency dependent conductivity has been studied using both modulus and conductivityformalisms. We have observed that the variation of the power law exponent withLi2O content is in contrastto that for the Li2O–Bi2O3 and Li2O–Bi2O3–PbO glasses. The values of the non-exponential parameter for theLi2O–Bi2O3–SrO glasses are lower thanthose for the binary Li2O–Bi2O3 glasses.

Magnetic Properties of Rapidly Quenched Ternary Oxides Li2O–Bi2O3–Fe2O3 System

Ternary oxides in the system Li2O–Bi2O3–Fe2O3 were prepared by rapid quenching from the melt by means of a twin-roller apparatus. As-quenched samples turned out to be X-ray amorphous, and ferromagnetic behaviour was observed at room temperature. Particularly, the amorphous (Li2O)25(Bi2O3)25(Fe2O3)50 specimen has magnetization value of about 4.5 emu/g (15 kOe) at room temperature. This specimen shows an irreversible thermomagnetization process below about 200 K in a weak magnetic field, indicating the existence of magnetic frustration. The 57Fe Mössbauer absorption spectra indicate that this specimen is composed of two different phases, short-range antiferromagnetic and ferromagnetic, and that the latter is less disordered (or crystallinelike). The magnetic frustration seems to be caused by the competition between exchange interactions at the interface of these phases.