Addition Of Li2O Research Articles

Effect of Li2O on physical, structural, thermal, optical, and electrical properties of mixed alkali borate glasses containing silver nanoparticles

In this work, mixed alkali borate glasses doped with Li2O were prepared with a molar composition of (75-x) B2O3-15Na2O-8CaO-1V2O5-1AgCl-xLi2O; x = 0, 5, 10, 15, and 20 mol% by using traditional melt-quenching process. X-ray diffraction studies confirmed the amorphous nature of the samples. Upon Li2O doping the glass density, measured at ambient temperature, increases from 2.336to 2.518 g/cm3, while molar volume decreases from 29.637 to 24.337 cm3/mol. The direct and indirect band gap energies determined using UV–Visible absorption analysis was in the range 3.000 –3.285 eV and 2.910–3.218 eV respectively. The DTA measurements indicated that with Li2O addition the thermal stability of the glasses has improved. FTIR study revealed the vibrational modes corresponding to the functional groups present in the glasses. The DC conductivity of the samples (measured at 588 K) was found to increase from 2.394 x 10-4 to 3.987 x 10-4 Ω-1m-1with Li2O content. The temperature dependency of DC conductivity followed Mott’s Small Polaron Hopping (SPH) model at high temperature and Variable Range Hopping (VRH) model at low temperatures. The linear fit of the data to the SPH model yielded the activation energy (W) values in the range 0.152 to 0.693 eV, whereas the density of states at Fermi level evaluated by the VRH model was in the order of 1030 eV-1m-3. The improved electrical conductivity of the prepared Li doped glasses together with their good thermal stability and transparency render them as potential candidates for optoelectronics device applications.

Study of Li2O reduction in mould slag for continuous casting of low-carbon steel slab

The addition of Li2O increases production costs for continuous casting, despite its enhancement of the melting and flow properties of mould slag. Initially, laboratory research focused on assessing the individual impacts of Li2O, F, Na2O and Al2O3 on the viscosity and melting temperature of the slag, using a basicity of 0.95. Subsequently, four stages of industrial testing were conducted to optimise the slag, evaluating parameters such as temperature and friction force curves of the mould copper plate thermocouple, steel slag consumption per ton and strand surface quality. The optimised slag achieved a basicity of 0.98, a viscosity of 0.29 Pa·s and a melting temperature of 1115 °C, meeting all performance requirements for low-carbon steel mould slag. Compared to the original flux, the mass percentage of Li2O decreased significantly from 1.54 to 0 wt-%, while Na2O increased from 2.36 to 7.35 wt-%, and Al2O3 decreased from 7.28 to 3.49 wt-%. The operation of the optimised flux remained stable, with smooth fluctuations observed in the mould copper plate thermocouple temperature and friction force curves. These research findings hold significant reference and practical value for further development and application.

In the LiCl-KCl melt at 500<sup>о</sup>С depending on the content of Li<sub>2</sub>О и LiOH

Molten alkali metal chlorides used in pyrotechnologies are aggressive corrosive agents. The high operating temperature of the process, the heterogeneity of the environment, and the significant corrosion activity of the molten salt necessitate both the search for stable structural materials and the development of methods for protecting the structural elements of high-temperature technological devices. Corrosion loss reduction techniques traditionally used in low temperature environments are not applicable at high temperatures. The article examines the influence of oxygen-containing impurities (lithium oxide and hydroxide) on the corrosion behavior of metallic nickel (grade NP1) – the main component of candidate structural alloys, a thermodynamically and structurally stable material in the melt for the process of electrolytic refining of spent nuclear fuel. A method for preparing the LiCl–KCl salt electrolyte and obtaining lithium oxide by thermal decomposition of anhydrous lithium hydroxide under vacuum is described, and the concentrations of impurities in the electrolyte and the synthesized lithium oxide are determined. An installation for conducting corrosion tests in an inert atmosphere of a glove box is presented. To assess the corrosion resistance of the material, the following were used: gravimetric analysis, X-ray diffraction analysis of the surface and cross-sectional sections, and X-ray diffraction analysis of the surface of the samples. The dependences of the corrosion rate of the material on the concentration of oxygen-containing additives Li2O and LiOH were obtained. Based on a combination of gravimetric, X-ray microspectral and X-ray phase analysis data, it was established that metallic nickel samples demonstrate high corrosion resistance in the studied melts with the introduction of Li2O and LiOH additives.

Retraction Note: An investigation of the structural-optical properties of Ni2+- bearing borate glass by Li2O addition

Retraction Note: An investigation of the structural-optical properties of Ni2+- bearing borate glass by Li2O addition

Spark plasma sintering of Ruddlesden–Popper Ca2−xDyxMnO4 ceramics: Impact on thermoelectric and mechanical performance

Abstractn‐type Dy‐doped Ca2MnO4 powders with the Ruddlesden–Popper structure were synthesized by the combustion method and sintered by conventional sintering and spark plasma sintering (SPS). Conventional sintering fails to densify Ca2MnO4, but the addition of Li2O proves to be a highly effective sintering additive, albeit with a detrimental impact on electrical conductivity. In contrast, SPS at 850°C for 1 min yields nanostructured, nearly fully dense samples, demonstrating superior outcomes. The dimensionless figure of merit ZT reaches 0.02 at 750°C. Additionally, the best sample exhibits a remarkable hardness value of 10.7 GPa, underlining the excellent mechanical properties achieved through this innovative approach.

Li2O concentration influenced local structure and properties of molten LiCl salt by machine learning driven molecular dynamics simulation

Pyroprocessing is one of the promising technologies for the reprocessing of spent nuclear fuel. In the electrolytic reduction process of pyroprocessing, LiCl serves as the electrolyte with a minor addition of Li2O as the initial oxygen ion input. Investigating the impact of Li2O concentration on the molten salt system is essential for enhancing the efficiency of electrolytic reduction. In the present study, the LiCl-Li2O system is simulated using deep potential molecular dynamics simulation. The properties including self-diffusion coefficient, shear viscosity, ionic conductivity, heat capacity, radial distribution functions, coordination numbers, short-range order, medium-range order, Voronoi structure, and angle distribution functions are explored at different Li2O concentrations. This study reveals that the variations of physical properties at different Li2O concentrations in LiCl molten salt can be attributed to the changes in local structure. For example, unnormal high proportions of two Voronoi structures are found in the molten salt when the Li2O concentration increases, which may explain the changes of properties. These findings offer valuable insights for refining the parameters of electrolytic reduction and elucidating the correlation between microscopic and macroscopic phenomena.

Effect of Li2O on the structure and properties of low‐boron aluminosilicate fiber glasses from molecular dynamics simulations and quantitative structure–property relationship analysis

AbstractMixed alkaline earth (MgO, CaO) aluminosilicate glass fibers (MCAS) with and without boron are commonly used as reinforcements in plastic composites, and the fundamental understanding of the thermal and mechanical properties is essential to the design of new glass compositions to satisfy the growing demands in applications from renewable energy to lightweight structural components. In this work, a series of Li2O containing low‐boron MCAS fiber glasses have been studied by using molecular dynamic (MD) simulations with recently developed effective partial charge composition dependent boron potentials. Structural characteristics, such as pair distribution function, bond angle distribution, and neutron/X‐ray diffraction structure factors, were calculated, as well as properties such as elastic moduli and vibrational density of states. The addition of Li2O was found to improve the elastic moduli of the fiber glasses in excellent agreement with experimental results we reported earlier. The simulation results showed that the weakened network connectivity and decrease of tri‐/bridging oxygen have positively affected the lowering of liquid temperature, owing to the transformation to more boron Q2 and silicon/aluminon Q3. It is found that higher oxygen packing density, coordinated aluminum/boron species such as [AlO5] and [BO4] units, larger‐membered oxide rings, and intensified connections of [AlOx] and [SiO4] are the main reasons that lead to improved mechanical properties. MD‐based quantitative structure–property relationship analyses were performed and showed excellent correlations to measured properties, indicating that it is a promising approach to understand glass properties and design new glass compositions for functional applications.

Li2O addition as a means of achieving low-temperature densification of SiC ceramic

In order to achieve low-temperature densification of SiC ceramic, β-SiC nanopowder was doped with Li2O together with Y2O3–Al2O3–MgO as sintering aids, and then spark plasma sintered at temperatures ranging from 1450 °C to 1600 °C for 30 min under 30 MPa pressure in argon. The densities, microstructures and mechanical properties of SiC ceramics were systematically investigated, in comparison to the counterparts sintered with Y2O3–Al2O3–MgO additives. Since Li2O has a low melting point, Li2O addition effectively decreased the formation temperature of liquid secondary phase, enabling SiC ceramics to obtain higher density and lower porosity after low-temperature sintering (T ≤ 1550 °C). Besides, Li2O addition was found to decrease the viscosity of liquid phase and enhance grain growth of SiC through dissolution-reprecipitation process. When sintered at 1550 °C, Li2O addition led to a remarkable increase of density from 3.03 g/cm3 to 3.21 g/cm3 for SiC ceramic. Meanwhile, the SiC ceramic with Li2O addition exhibited a high Vickers hardness of 22.75 ± 0.35 GPa and a good fracture toughness of 3.83 ± 0.27 MPa m1/2. The research results are expected to benefit the low-cost fabrication of SiC ceramics based on pressure-assisted sintering and alleviate the thermal damage of SiC fiber in hot-pressed SiCf/SiC composites.

High thermal stability molybdenum-Boosted lithium tellurite glass for radiation shielding

A novel glass system was developed using the melt-quenching technique. The primary aim was to investigate molybdenum-rich compositions (MoO3 > Li2O), with the general formula (69–2x) TeO2–(31+x)–MoO3–xLi2O (where x = 0, 5, 10, and 15 mol%). The physical, structural, thermal, mechanical and radiation shielding properties were evaluated. The synthesized glasses were characterized through their densities, molar volumes, and oxygen packing density, which revealed that the density and molar volume decreased as the amount of Li2O and MoO3 increased in the glass structure, while the oxygen packing density increased as a function of both Li2O and MoO3. Raman spectroscopy was used to analyze the glass structure, which showed a superimposed reduction of all Te units due to the formation of Te–O–Mo and a coordination change from MoO4 to MoO6. The interplay between Li2O and MoO3 has a direct effect on the thermal stability of the glass and reveals that glasses with higher MoO3 content and lower Li2O content exhibit enhanced thermal stability. The mass attenuation coefficient for the synthesized systems varied from 37.07 to 32.38 cm2 g−1 at 0.015 MeV. The fast neutrons removal cross-section exhibits a range from 0.090 to 0.096 cm−1 across all samples, while the thermal neutrons cross section values lie within the interval of 1.22–8.16 cm−1. The glass sample with the highest concentration of TeO2 showed superior values of mass attenuation, and fast neutrons removal cross-section, along with the lowest values of half value layer and mean free path. Nevertheless, the addition of MoO3 and Li2O improved thermal stability and led to adequate radiation protection levels. The results indicate the significant potential of MoO3-rich tellurite materials for shielding against gamma-ray and neutron radiation.

The basic intermediate-range order structures in the FLiNaK–LaF3–Li2O melt: identification and characterisation

ABSTRACT In this paper, we investigate the structure of FLiNaK–LaF3 melt with small addition of Li2O through the theoretical approach combining ab initio molecular dynamics and simulation of the isolated structural units. The structure of the melt was studied in detail by calculation of radial distribution functions along with coordination numbers and radii. We found that oxyfluoride intermediate-range structure is formed in the melt. Our observations support the suggestions of other authors on formation of intermediate-range structures in fluoride melts containing metal oxides. Given structure shows long lifetime, the consideration of the isolated specie is valuable. We performed a simulation of ‘gas-phase’ [O2La4Fn] structure in order to calculate its Raman spectrum. It was found that the spectrum of the isolated structure agree in semi-quantitative manner with the vibrational density of states of the oxygen ions in the melt.

Antibacterial, Optical, Structural, and AC Conductivity Characteristics of Lithium-Doped Barium Zinc Borate Glasses for Multiple Applications

An Li2O-incorporated bioactive glass system of chemical composition xLi2O-10BaO-10ZnO-(80-x)B2O3 with x = 0–20 mol% was synthesized by melt-quench route. Non-crystalline behaviour was confirmed with X-ray diffraction spectra. The antibacterial zone of inhibitions increased with Li2O incorporation. Experimental densities increased with Li2O molar content and molar volume decreased. UV-Optical absorption spectra confirmed a cut-off wave length (λ c) increasing trend by NBOs. Indirect band gap decreased, direct band gap decreased, and Urbach energy increased with Li2O addition. The refractive index of the glass system also increased. Fourier transform infrared and Raman spectroscopy studies confirmed the structural variations and existence of metal-oxides in the glass matrix. The AC conductivity increased with frequency, temperature, and also Li2O content by almost three orders of magnitude. The findings of higher order conductivity (10−3Ω−1cm−1), improvement in the zone of inhibitions upto 15 mm against E. coli., and 14 mm against Salmonella; higher value of refractive index (n > 2) confirms the multiple applications of these glasses.

Dense and high flexural strength cordierite ceramics doped with Li2O

High-strength cordierite ceramics with Li2O were fabricated by non-pressure sintering. The results showed that the addition of Li2O significantly reduced the sintering temperature and expanded the sintering range. Additionally, the mechanical strength of the samples clearly increased after Li2O doping. In particular, the sample with 0.5 wt% Li2O sintered at 1250 °C showed the best properties, with a flexural strength of 178.6 MPa and a thermal expansion coefficient of 2.1 × 10−6 °C−1. Its flexural strength is much higher than samples without Li2O and the cordierite ceramics prepared by non-pressure sintering reported in the literature. The high density of the sample (2.52 g cm−3) is the main reason for its excellent mechanical properties. Furthermore, first-principles calculations verify that Li+ dopants insert at the vacant channel of α-cordierite crystal with six-fold coordination, which may reduce the anisotropy of the thermal expansion coefficient of α-cordierite, thus improving the strength of ceramics.

Enhanced comprehensive performance of Y2O3-Al2O3-SiO2 glass filler for SiC brazing by Li2O additive

Effects of Li2O additive on the network structure, crystallization behavior, thermal expansion properties and wettability of Y2O3-Al2O3-SiO2 glass were investigated. The results showed that Li2O could depolymerize the network structure, decreasing the characteristic temperatures of glass. The coefficient of thermal expansion of glasses varied from 5.09×10−6 K−1 to 8.03×10−6 K−1 by changing the Li2O addition and heat treatment process. Meanwhile, Li2O inhibited the crystallization of high-melting phases, consequently improving the fluidity of molten glass. The glass with 3 wt% Li2O showed an excellent wettability on SiC ceramic with a contact angle of 18°, and a sound joint mainly consisted of glassy phase was obtained at 1430 ℃ for 30 min. The prepared joints exhibited a shear strength of 119.7±20.3 MPa, which is 5.4 times of that without Li2O. After 3 times of water-quenching from 1200 ℃, the joints remained 68.4% of its original strength, demonstrating graceful reliability.

RETRACTED ARTICLE: An investigation of the structural-optical properties of Ni2+- bearing borate glass by Li2O addition

RETRACTED ARTICLE: An investigation of the structural-optical properties of Ni2+- bearing borate glass by Li2O addition

Effect of Li2O on Physical, Structural, Thermal and Electrical Properties of MgO-V2O5 Glasses

Three compositions 75V2O5-25MgO (MVL-0), 75V2O5-16MgO-9Li2O (MVL-9) and 75V2O5-13MgO-12Li2O (MVL-12) were synthesized by melt-quench technique. Addition of Li2O instead of MgO promoted the devitrification of magnesium vanadate glass. X-ray diffraction pattern showed the amorphous nature of MVL-0, while MVL-9 and MVL-12 were seen to exhibit a lithium vanadium oxide phase with the presence of some amorphous phase. Densities of the samples increased with the increase in Li2O concentration. Raman spectra of MVL-0 exhibited broad band as compared to the other samples; as Li2O concentration increased, the band became sharp including the appearance of some more new bands. High electrical conductivity was observed for MVL-12; ∼9.615×10–5 S.cm–1 at 50°C to 1.96×10–3 S.cm–1 at 250°C, which is comparable to the conductivity of standard cathode materials used in battery and electrochemical fuel cells. So, these samples may be used as cathode materials due to good conductivity at 250°C for battery and electrochemical fuel cells.

Radiation shielding performance of recycled waste CRT glasses doped with Li2O and Y2O3: Potential applications in medical facilitates

In this study, waste cathode ray tube screen glass (WCSG) doped with Li2O and Y2O3 was prepared and investigated for physical properties, structural definition, and their charged radiation and neutron shielding competence through a series of experimental and theoretical approaches. Using the cold isostatic press method, WCSG-infused Li2O + Y2O3 composite glass ceramic samples were prepared. The Li2O + Y2O3 composite concentrations were varied from 0 (STV), 10 (STV-YLI1), and 20 (STV-YLI2) wt%. The prepared glasses were sintered, and their crystal structure and surface microstructure were probed using the XRD technique and SEM images. The prepared samples were analysed for their radiation shielding abilities, starting from the computation of parameters related to their interaction with charged radiation and neutrons. The ESTAR, PSTAR, ASTAR, and STRIM software. In addition, the fast neutron (FN) removal cross section (FNRCS) and thermal neutron (TN) total cross-section (σtot) for the prepared glasses were evaluated theoretically using established models. The XRD spectra of the samples showed distinct crystalline structure and the formation of glass-ceramic material. The addition of the Li2O + Y2O3 composite reduced surface pores, increased hardness, and increased the sample density. The Vickers hardness values were calculated as 495, 527, and 552 HV for the STV, STV-YLi1, and STV-YLi2 samples, respectively, while the corresponding densities were 2.506, 2.592, and 2.634 g/cm3. The addition of Li2O + Y2O3 to the WCSG slightly improved the glass-ceramic system's charged particle shielding ability. The FNRCS of STV, STV-YLi1, and STV-YLi2 are 0.0775, 0.0827, and 0.0867 cm-1 respectively. The ability of the prepared glass ceramics to absorb fast and thermal neutrons improved with the addition of Li2O + Y2O3. The materials are recommended for use as environmental friendly radiation shields.

Preparation and Electrochemical Dissolution of a Soluble Uranium Oxycarbide Anode.

A soluble uranium oxycarbide (UC0.4O0.6) anode was synthesized by a carbothermal reduction process, using U3O8, UO2, and graphite as raw materials, in a vacuum environment of 0.1 MPa at 1750 °C. The sintered UC0.4O0.6 exhibited excellent conductivity and stability in LiCl-KCl molten salt. The dissolution process of UC0.4O0.6 in molten salt was analyzed by linear sweep voltammetry (LSV), and the initial dissolution potential, rapid dissolution potential, and passivation potential were determined. The oxidation/reduction process of dissolved uranium ions in LiCl-KCl molten salt was studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). The experimental results showed that the addition of Li2O significantly reduced the volatilization of U(VI) and increased the concentration of UO22+ in molten salt. Finally, the product was conducted by electrolysis at 1.0 V and was confirmed to be UO2 by XRD and SEM-EDS analysis.

The impact of oxide impurity on the structure of FLiNaK and FLiNaK–CeF3 melts: A simulation study

Oxide impurities affect the performance of the molten mixtures applicable in molten salt reactors. To reveal the underlying reasons of changes in physicochemical properties, the in-depth investigations on microscopic structure of melts are demanded. In this study, the FLiNaK and FLiNaK–CeF3 molten mixtures with small addition of Li2O were simulated within the ab initio theory to obtain the local structure patterns. The emphasis is placed on oxygen-based groupings since these are expected to be the most stable. In order to estimate the stability, the calculation of ion pair lifetimes was performed. It is shown that the most probable ion groupings existing in the FLiNaK–Li2O melt are [OLi5K], [OLi5K2] and [OLi4NaK2], while the FLiNaK–Li2O–CeF3 melt contain [OCe2Li2], [OCe2Li2K], [OCe2Li3] and [OCe3Li] units predominantly. Within the groupings, the most stable ion pairs are O-Li or O-Ce, depending on the melt composition.

КОРРОЗИЯ КОНСТРУКЦИОННЫХ МАТЕРИАЛОВ В РАСПЛАВЛЕННЫХ ХЛОРИДАХ ЩЕЛОЧНЫХ МЕТАЛЛОВ

The corrosion process of 12X18H10T steel in a KCl-Nacl melt with the addition of Li2O (0-11000 ppm O2-), as well as lanthanum, cerium and neodymium trichlorides, was investigated. The concentration interval of lithium oxide in the LiCl-KCl melt is determined in the range from 0 to 0.2 % by weight of Li2O, at which the corrosion rate decreases by 5–6 times. The concentration interval of lithium oxide in the LiCl-KCl melt is in the range from 0 to 0.2 % by weight of Li2O, at which the corrosion rate decreases by 5–6 times.

Effect of small additions of Li2O on phase separation and crystallization of barium‐silicate glasses

AbstractIt is known that the addition of Li2O to 33.3BaO‐66.7SiO2 glass, whose composition is the same as BaSi2O5, promotes crystallization of BaSi2O5. In this study, in order to clarify the effect of a smaller amount of Li2O, xLi2O‐(30‐x)BaO‐70SiO2[mol%] (x = 0, 0.2, 0.5) glasses were prepared. The main crystalline phases in the heat treatments near the maximum crystallization peak temperature, were high‐BaSi2O5 and low‐BaSi2O5 which transformed from high‐BaSi2O5. It is found that the introduction of only 0.2 mol% and 0.5 mol% Li2O significantly changes the crystallization behavior. In the composition without Li2O, only high‐BaSi2O5 was formed after heat treatment even for 24 h. For compositions containing Li2O, low‐BaSi2O5 was formed within 1 h of heat treatment. In these compositions, it is found that the addition of Li2O enhances phase separation in the early stage of heat treatment, resulting in the formation of Si‐rich droplet phases and Ba‐rich phases. The composition of the Ba rich glass phase would be close to the stoichiometric composition of BaSi2O5, suggesting a significant change in crystallization behavior.