Li2O Content Research Articles

Preparation of Battery-Grade Lithium Composites from Local Spodumene

Nowadays lithium metal is considered as one of the key elements in modern industry. Its usages range from pharmacy to aeronautics including energy storage devices and glass-ceramics. However, since 2005, Lithium-ion Batteries (LiBs) have taken over, as they play a major role in the development of the electronic and green industries [1]. LiBs show the highest growth rate and are expected to take an even bigger part in the lithium industry. The expected growth rate for lithium carbonate and lithium hydroxide is respectively 10% and 14.5% until 2025 [2], since they are two of the raw materials used for LiBs. In 2016, lithium carbonate prices were reported to range from 10,000 US$ to 16,000 US$ while lithium hydroxide prices were reported to range from 14,000 US$ to 20,000 US$ [3].The lithium production was, until recently, dominated by the Salt Lake brines, because of their cheaper production cost. The ever-growing demand in lithium compounds led to the regaining of interest for another source, after the lithium price increased. This other source, lithium rich minerals, now account for 50% of the world’s lithium production [4]. Lithium minerals are numerous and include spodumene, eucryptite, petalite, bikitaite, etc. [5].Among those minerals, spodumene LiAlSi2O6 is the most common and the most studied. It offers a theoretical Li2O content of 8 wt %, whereas raw minerals in nature typically offer 1 to 2 wt % Li2O.In Kazakhstan, all known lithium reserves are associated with spodumene and according to U.S. Geological Survey, Mineral Commodity Summaries made in January 2020, Kazakhstan has approximately 50000 tons of lithium [6]. And according to the Kazakh National Technical University, lithium in the process of operation is usually not separately extracted and all goes into the waste "tailings" of the deposits.In this work preliminary results on the development of the optimal leaching process of lithium composites from Kazakhstani spodumene will be presented. The new process offers a fast throughput, direct leach process for spodumene concentrates to produce battery grade lithium hydroxide and / or lithium carbonate monohydrate products. The process is also environmentally sustainable. The leach process is totally sulfate and acid free and the refining process does not involve any crystallization of unnecessary by-product salts.[1] Sociedad Quimica y Minera de Chile, 2003 to 2013, Annual Reports; SQM: Santiago, Chile, 2003–2013[2] SignumBOX. Analysis: Lithium, Batteries and Vehicles/Perspectives and Trends; SignumBOX: Santiago, Chile, 2014; p. 8[3] Jaskula, B.W. Lithium, 2016 Mineral Yearbook 2018; USGS: Reston, VA, USA, 2018; p. 44.1[4] U.S. Geological Survey. Mineral commodity summaries 2016: U.S. Geological Survey Lithium; USGS: Reston, VA, USA, 2016; p. 202[5] Labbé, J.F.; Daw, G. Panorama 2011 du marché du lithium; Rapport public 2012, BRGM/RP-61340-FR; BRGM: Orléans, France, 2012; p. 94[6] U.S. Geological Survey, 2020, Mineral commodity summaries 2020: U.S. Geological Survey, 200 p., https://doi.org/10.3133/ mcs2020

Effect of CaF2 and Li2O on structure and viscosity of low-fluoride slag for electroslag remelting of rotor steel

The structure and viscosity of CaF2-CaO-Al2O3-B2O3-SiO2-Li2O slag with varying CaF2 and Li2O contents were investigated by Raman spectroscopy, 27Al, 29Si and 11B magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, and rotating cylinder method, respectively. The relative fraction ofQAl2 significantly increases, the fractions ofQAl3 andQAl4 decrease with increasing the CaF2 or Li2O content. Aluminum exists in the form of four-coordinated aluminum (AlⅣ) corresponding to AlO4 and a small amount of AlO3F. The fraction ofQSi0 species increases at the expense ofQSi1,QSi2(1Al) andQSi2 with increasing the CaF2 or Li2O content. B is present in the form of BⅢ, besides 0.57% of BIV in the glass with 14.69mass% CaF2. The relative fraction of T0 increases and T1 decreases as the CaF2 or Li2O content is increased. The degree of polymerization of aluminosilicate and borates decreases with increasing the CaF2 or Li2O content, which is consistent with the results of viscosity and viscous activation energy.

Effect of CaO/SiO2 mass ratio and Li2O on structure and phase precipitation behaviors of CaO–SiO2–MgO–Al2O3 oxide inclusions

The crystallization behaviors and structure of CaO-SiO2-MgO-Al2O3 melts representing the oxide inclusions in Si-Mn-killed steel were investigated. Raman spectroscopy analysis indicates that the degree of polymerization of oxide melts is lowered with increasing the CaO/SiO2 mass ratios or Li2O contents. Lowering the CaO/SiO2 mass ratios decreases the crystallization temperatures and suppresses crystallization of the oxide melts. Two crystalline phases precipitate (4CaO·MgO·Al2O3·3SiO2 and 3CaO·MgO·2SiO2 in sequence) during continuous cooling of oxide melts with the CaO/SiO2 mass ratios of 1.55 and 1.15. Only one crystalline phase (4CaO·MgO·Al2O3·3SiO2) was precipitated during the continuous cooling of the oxide melts with CaO/SiO2 mass ratio of 0.77. The crystallization ability of oxide melts was retarded with increasing the Li2O content. The crystalline phases precipitated sequentially are blocky 4CaO·MgO·Al2O3·3SiO2 and faceted 3CaO·MgO·2SiO2 irrespective of the Li2O content of oxide melts.

Mineralogical Variability of the Whabouchi Pegmatite and its Effect on the Li Concentrations

ABSTRACT The Whabouchi pegmatite, located in the James Bay area of Québec, is a lithium-cesium-tantalum pegmatite of albite-spodumene type. In order to evaluate the mineralogical and geochemical variability of the pegmatite, 168 samples were collected from drill core and analyzed for their whole rock geochemistry and mineralogy. The pegmatite is composed of quartz, albite, K-feldspar, spodumene, and muscovite, with trace amounts of spessartine garnet, apatite, beryl, tourmaline, and oxides. It is mostly homogenous, showing greatest variability with respect to the minerals albite, K-feldspar, and spodumene. The Li2O concentration varies between 0.03 and 4.46 wt.%, for an average of 1.53 wt.% and an estimated variability of 53%. Modal mineralogical data showed an inverse correlation between spodumene and the feldspars (albite + K-feldspar), which could also be observed when comparing the Li2O content with the sum of Na2O and K2O. To improve on this relationship, correlation matrices comparing all geochemical components were constructed and allowed the development of an equation able to estimate the Li2O content of the samples within 0.5 wt.% of the measured value. The applicability of the equation to other albite-spodumene type pegmatites was verified with samples collected from the Georgia Lake area of northwestern Ontario. The calculation provided a good approximation of the Li2O content of the samples, with 92% of the data showing a difference of 0.5 wt.% Li2O or less; however, it has an impact on the statistical mean of the data set, the data being recalculated to return an average closer to 1.5 wt.% Li2O. Considering the difficulty in analyzing lithium content of an in situ sample, this relationship could facilitate estimation in the field using portable X-ray fluorescence with the capability of analyzing all required components.

Structural, thermal and nuclear shielding properties of lithium lead phosphate glasses: Influence of lithium oxide additive

In this paper, the structural, thermal and nuclear radiation shielding properties of a new Lead–Lithium-Phosphate glass system with different amount lithium oxide were studied. The glass samples were prepared by the conventional melt-quenching method and they having compositions (75-x) P2O5– 25PbO- xLi2O with x = 0, 5, 10, 15, 20 mol%. The influence of Li2O content on the structural, thermal, radiation shielding properties, and other related properties of the synthesized glasses was studied. The structural properties were investigated using XRD and Raman spectroscopy. The glass transition temperature Tg and crystallization onset temperature Tx are estimated from the DSC profile.The GEANT4 Monte Carlo simulation code was used to estimate thermal neutron attenuation coefficient (μnt) in a wide neutron energy range of 0.0253–100 eV and ParShield code was used to calculate effective fast neutrons removal cross-section (∑R). The gamma-ray attenuation parameters such as mass attenuation coefficients (μm), effective atomic number (Zeff), effective electron density (Neff) and half-value layer (HVL) have been computed by using ParShield code in the energy range of 0.103–1.33 MeV. However, the total mass stopping power (MSP) and projected range (PR) values have been estimated for alpha particles (4He2+) and Triton particle (3H) by using SRIM in the energy range of 0.1–10 MeV.

Governing mechanism of ion transport in lithium-iron-phosphate glasses

We show a fundamental relationship between network structural attributes and ionic transport of lithium iron phosphate glasses xLi2O–2Fe2O3–3 P2O5 (xLFPO; x = 0.375, 0.75, 1.5, 3.0) used for a cathode in lithium-ion batteries. The glass samples have been synthesized using a solid-state reaction method. We have investigated the electrical characteristics of the glass by combinational measurements of electrical impedance in the frequency 100 Hz – 30 MHz and temperature from ambient to 240 °C, differential thermal analysis, X-ray diffraction pattern, and Raman spectroscopy. The ionic hopping and relaxation processes in xLFPO glasses are analyzed by using Cole-Cole, power law, and modulus representations. We reveal that the exponential increase in dc conductivity with increasing Li2O in xLFPO glasses is caused by the combination of an increase in non-bridging oxygen sites and a change in the bonding forces of iron valence surrounding the iron phosphate clusters inside the network. The power law conductivity, which is driven by the fractional Rayleigh equation, exhibits that the rate of increase in dc ionic conductivity is the same as the rate of increasing numbers of the ionic charge carriers. Raman spectra show that the increase of depolymerization of the iron phosphate network with the addition of Li2O content is due to the conversion of Q2 to Q1 and Q0 species.

Molecular dynamic simulations study on the structure and properties of Li2O-containing magnesium aluminosilicate glasses

Magnesia aluminosilicate glass has important applications value in the fields of composite fiber reinforcement, flat panel display, aircraft windshields and so on because of its excellent chemical stability and good mechanical properties. In this paper, the molecular dynamic simulations were used to obtain structural information of the glasses, and the results were compared with Raman, X-ray photoelectron spectroscopy, Differential thermal analysis, and Vickers hardness to elucidate the effect of Li2O introduction on the structure and properties of MgO-Al2O3-SiO2 glasses. The transformation mechanism of oxygen type and polyhedral with the process of Li2O content was investigated, and focusing on the effect of network connectivity of the glass on the transformation temperature and hardness. The results indicated that at low Li2O content (< 3 mol%), Li ions play the role of charge compensator and reinforce the network structure of MgO-Al2O3-SiO2 glasses. When the Li2O content exceeds 3 mol%, the excess Li2O breaks the backbone of the Al-Si network structures that to the reduction of the glass network connectivity. The glass transition temperature and hardness of Li2O-MgO-Al2O3-SiO2 glasses reach a maximum at a Li2O addition of 3 mol%, while the corresponding simulated structures (AlO5 and Network Connectivity) show the most stable network structure.

Effect of Li+ ions on structural, optical and nano-crystallization behaviour of Na2O-CaO- P2O5-B2O3 glass system: Biomedical applications

Glassy system of composition xLi2O.3P2O5.21Na2O.26CaO.(50-x)B2O3 (x = 0, 1, 2, 3 and 4 mol%) was prepared by melt quench technique. X-ray diffraction, Infrared spectroscopy and Field emission scanning electron microscope with Energy dispersive spectroscopy were conducted to identify crystalline phase formation in glass powder and to study morphologies. The deconvoluted IR absorption spectra of synthesized samples, were analyzed to examine the structural rearrangements in the glass matrix before and after immersing in the phosphate solution. Optical band gap, Urbach energy and refractive index of the synthesized compositions were also obtained from the analysis of optical absorption spectra to examine the semiconducting behavior. The effects of the treatment in phosphate buffer solution for 12 days on crystallization & structural properties of these glasses were systematically investigated. The dependence of physical parameters on the glass composition suggested a variation in the number of non-bridging oxygen with Li2O content. Morphological and structural study alongside a possibility of hydroxyapatite formation suggests the biomedical applications of these materials.

Lithné fosfáty a slídy v leukogranitu typu Homolka

Homolka granite forms intrusion of highly fractionated leucocratic magma which belongs to the youngest members of the Moldanubian Pluton. The age of the intrusion was estimated between 319 and 315 Ma. The Homolka granite is P-rich, peraluminous and strongly enriched in Li, Rb, Cs, Sn, Nb, Ta and F, showing high U (8–20 ppm) and low Th (&lt; 3 ppm) contents. This study focuses on Li-bearing minerals – phosphates and white micas. Their modal proportions correspond to 1–3 vol. % and 5–15 vol. %, respectively. Both mineral groups occur in several generations in the rock. The first phosphate generation (for example, Al-bearing montebrasite or Fe-Mn-bearing triphylite) contains up to 11 wt. % Li2O. The first generation of mica (Li-phengite) contains about 7–8 wt. % F and up to 1 wt. % Rb2O with Li2O content ranging between 1.3 and 1.9 wt. %. The second generation of white mica, replacing Li-phengite, is depleted in F and Rb and shows decrease in Li2O to 0.5–0.9 wt. %. Despite the low total content of lithium (Li2O = about 0.1 wt. %) in the rock, the occurrence of the leucocratic Homolka granite is not negligible. Because of the high economic potential of lithium, these highly evolved peraluminous and lithium-bearing intrusions will deserve a special attention in the future.

Comparative assessment of fast and thermal neutrons and gamma radiation protection qualities combined with mechanical factors of different borate-based glass systems

Adequate shielding from ionizing radiations is essential in nuclear facilities because of such radiations’ adverse effects on humans in the event of unwanted or accidental exposure. In the current work, for four distinct compositions of B2O3-Li2O, Li2O-Na2O-K2O-B2O3, Gd2O3-SiO2-B2O3, and Bi2O3-Li2O-ZnO-B2O3 glass systems, neutron and γ-ray attenuation competencies combined with elastic features have been examined for feasible nuclear radiation protection purposes. ΣR (fast neutron removal cross-section) and for thermal energy neutrons σT (total cross-section) and SP (shielding percentage) were estimated. Comparably, in all samples, 50B2O3-10K2O-40Li2O (mol%) glass possesses larger ΣR (=0.11755 cm−1), whereas 25B2O3-37.5Si2O-37.5Gd2O3 (mol%) glass shows large σT (=646.171 cm−1) and SP for thermal neutrons at minimal thickness, indicating the included Gd2O3’s positive effect as element Gd has a high neutron absorption capacity. Employing the Phy-X/PSD program and MCNPX code, μ/ρ (mass attenuation coefficient) of all selected glasses is calculated for a γ-ray energy span of 0.015 – 15 MeV. Gd2O3 or Bi2O3 addition improved μ/ρ, and such increment is significant at low energies owing to PEA (photoelectric absorption) dominance and Gd or Bi K-edges. Also, for 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) glass, μ/ρ has been derived by the WinXCOM program and FLUKA, Geant4, and PHITS codes, and a good accord between such simulated and theoretical μ/ρ outcomes is noticed following the calculated relative differences. Next, linear attenuation coefficient, effective atomic number and electron density, MFP (mean free path), TVL (tenth-value layer), HVL (half-value layer), and RPE (radiation protection efficiency) have also been evaluated. Comparatively, at 1.25, 0.662, and 0.2 MeV energies, 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) sample possesses lower MFP and HVL than five SCHOTT AG commercial glass shields. Approximated RPE results affirmed all Gd2O3-SiO2-B2O3 and Bi2O3-Li2O-ZnO-B2O3 samples’ potent absorption (almost 100%) ability for lower energy γ-rays. Moreover, equivalent atomic number, and by geometric progression fitting process, within energy 15 keV–15 MeV extent for ten different penetration depths at 1–40 mfp span buildup factors have been assessed. 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) glass exhibits better gamma-ray shielding effectiveness in all chosen samples, specifying Bi2O3’s favorable impact. Changes in photon shielding factors were interpreted following pair production, Compton scattering, and PEA processes. Later, elastic (Young’s (Y), bulk (K), shear (S), and longitudinal (L)) moduli and Poisson’s ratio values have been calculated for all inspected glasses. BC (bond compression) and M-M (Makishima–Mackenzie) models were utilized for such elastic traits reckoning. All K, Y, S, and L values’ trends for binary B2O3-Li2O glasses were identical in both BC and M-M models, and Kbc was found to be raised from 73.63 to 89.89 GPa, while KM–M increased from 75.35 to 180.53 GPa accordingly when Li2O content improved from 9.6 to 39.9 mol% in the chemical composition.

Structural and Optical Studies of Quaternary Glass System

The new tellurite glasses with chemical composition 64TeO2-15CdO-(20-x) ZnO-xLi2O-1V2O5 (x= 0, 5, 10, 15 and 20 mol %) were synthesized by traditional melt quench hardening method. The glass samples showed broad humps of typical amorphous phase in the X- ray diffraction patterns. The physical properties of glass samples such as density (ρ), molar volume (Vm), oxygen packing density (OPD), refractive index (n), molar refractivity (Rm) and metallization parameter (M) were estimated. The Fourier transform infrared spectroscopy (FTIR) studies exhibited that replacement of ZnO by Li2O forms significantly some basic structural units of TeO4, TeO3/TeO3+1 and ZnO4. Differential scanning calorimetry (DSC) was employed to find out the glass transition temperature (Tg) and thermal stability ( ). The optical enthrallment studies exhibited that the cut-off wavelength (λ) decreases while optical energy gap (Eopt) and Urbach energy ( ) values increases with an increase an escalation of Li2O content. This tellurite glasses possess an important use such as sensor devices, storage of data system and industrial applications etc.

Influences of Al2O3 content on crystallization and physical properties of LAS glass-ceramics prepared from spodumene

Low thermal expansion Li2O-Al2O3-SiO2 transparent glass-ceramics with low Li2O content and relatively high total content of Na2O and K2O (> 2.00 wt.%) were prepared from spodumene. And the influences of Al2O3 addition on structure and properties of such LAS glasses and glass-ceramics were investigated. The crystallization behavior and structure of the samples were explored by differential scanning calorimetry (DSC), X-ray diffraction (XRD), magic-angle-spinning (MAS) NMR, Fourier transform infrared spectrometer (FTIR), and scanning electron microscope (SEM). The results show that the addition of Al2O3 contributes to the precipitation and transition of β-quartz solid solution (s.s.) Besides, the smaller grains can be obtained in glass-ceramics with higher Al2O3 content, resulting in the higher visible transmittance. When the Al2O3 content is 21.00 wt.%, the transparent and low coefficient of thermal expansion (CTE) samples crystalized at 860 °C present the best mechanical properties.

Optical properties and radiation shielding performance of tellurite glasses containing Li2O and MoO3

Tellurite glasses own some unique properties that can serve human being developments in several applications. This research work aims to study the optical properties and radiation shielding performance of tellurite glasses containing Li2O and MoO3 described by the formula of xLi2O – (80–2x)TeO2 – (20+x)MoO3, where x = 0, 10, and 20 mol%. The results of the optical studies show that the optical transmission (T) of the studied glass samples increased from 1.21 to 1.42 as the Li2O content increased from 0 to 20 mol%. Such increase was associated with a clear decline in the values of the static dielectric constant of the samples. On the other hand, FLUKA simulation was extensively used to assess and test the radiation shieling performance for each sample involved. The findings of this part reveal that the attenuation factors (e.g. MACs) of LTM glasses varied from 0.038003 cm2/g to 0.16151 cm2/g for LTM-A, from 0.03813 to 0.15611 cm2/g for LTM-B and from 0.03825 cm2/g to 0.14948 cm2/g for LTM-C. Moreover, the transmission factors (e.g. HVLs) of the LTM glasses were minimum at 0.284 MeV with value of 0.814437 cm, 0.90430 cm and 1.03275 cm for LTM-A, LTM-B and LTM-C, respectively. Finally, a large scale comparison was achieved between the studied glass samples and the commercially available ones for several photon energies. This comparison confirmed the utility of using the present glass samples as transparent shielding materials in several applications whether this is in hospitals or any other technological facilities.

Effects of Li2O on structure of CaO-SiO2-CaF2-Na2O glasses and origin of crystallization delay

The structure and kinetics in the glass system with increasing Li2O contents were characterized to determine how Li2O interrupts melt crystallization of cuspidine in CaO-SiO2-CaF2-Na2O glasses, despite the observations that Li2O reduces the polymerization degree of silicate and the viscosity, and that these reductions generally accelerate crystallization. 19F MAS NMR and molecular dynamic simulation showed that Li2O formed LiF bonds and distributed tetrahedral environment of fluorine, thereby disrupting the interaction of fluorine, one of the major components that compose cuspidine. Most of the displaced calcium from fluorine interacted with NBO of silicate, resulting in the decreased self-diffusion coefficients of Ca2+ ions. Therefore, these results show that Li2O delays crystallization by interfering with the Ca-F interaction and lowering the activity of fluorine despite depolymerizing the silicate network.

Effect of Li2O on rheological properties, structure, and crystallization of mould flux for high-speed thin-slab continuous casting

ABSTRACT The effects of Li2O content on the rheological properties, melt structure, and crystallization behaviour of mould flux for high-speed thin slabs are systematically studied. The results show that when the Li2O content increases from 0.86% to 5.81%, the viscosity of the mould flux decreases, the melting range increases, and the break temperature initially decreases followed by an increase. Further study shows that Li2O can release O2− and depolymerize complex Si–O–Si and Al–O–Al structural units into Si–O and Al–O structures. Simultaneously, Li2O can compensate for the charge between Si4+ and Al3+ by providing Li+ in combination with the mould-flux network structure, making the Si–O–Al structure unit more stable. With the increase in Li2O content in the slag, the crystallization of the mould flux is inhibited at first, and subsequently, it is enhanced. When the Li2O content is 4.33%, the precipitation of Lithium metaaluminate enhances the crystallization behaviour of the mould flux.

Investigation of the gamma-ray shielding performance of the B2O3-Bi2O3-ZnO-Li2O glasses based on the Monte Carlo approach

The purpose of this article is to investigate the shielding performance of the B2O3-Bi2O3-ZnO-Li2O glasses against the gamma-ray. To this end, the attenuation parameters of the gamma-ray inside the B2O3-Bi2O3-ZnO-Li2O glasses were evaluated in the energy range of 200–1500 keV. It was found that the mass attenuation coefficient of the composites increases with increasing the Li2O content. The relative percent deviation between the results of simulation using the MCNPX and XCOM database in most cases was less than 2%. Additionally, the Mean Free Path (MFP) and Half-Value Layer (HVL) parameters were evaluated, and the shielding efficiency of samples was compared with some conventional shielding material in the term of HVL. The results show that among the examined samples, the B4 glass sample has the best shielding performance against the gamma-ray.

Investigation of structural and impedance spectroscopic properties of borate glasses with high Li+ concentration

Lithium borate glasses prepared by melt-quench technique have been studied with a view to ascertain their structural and electrical properties. FTIR analysis of the present samples reveals the absence of boroxol rings, presence of structural units of lithium formed with oxygen and increase in the number of Non-Bridging Oxygens (NBOs) in the glass system. The real and imaginary parts of dielectric constant increase with frequency and temperature arises due to interfacial ionic polarization. The non-exponential Kohlrausch-Williams-Watts (KWW) function has been found to follow by the imaginary part of electric modulus, thereby confirming its applicability. The fitting of data of ac conductivity as per Jonscher's universal power law indicates hoppable ion concentration dependent upon temperature and Li2O content. The analysis is further supported by the variations of ac-conductivity as well as the activation energy for dc conductivity. A decrease in impedance and increase in the space charge polarization is observed with increasing Li2O concentration. Further, the electrical behavior of samples has been investigated via an impedance equivalent circuit corresponding to the Nyquist plot.

Vibrational, thermal and optical studies of 30TeO2-39.5B2O3-(30-x)ZnO-xLi2O-0.5 V2O5 (0 ≤ x ≤ 30 mol%) glass system

A series of glasses with novel composition 30TeO2-39.5B2O3-(30-x)ZnO-xLi2O-0.5V2O5 (0 ≤ x ≤ 30 mol%) were prepared using melt quenching technique. All glasses were characterized using XRD, Fourier transform infrared (FTIR) and Raman spectroscopies, Differential Scanning Calorimetry, Optical absorption and Electron Paramagnetic Resonance. The physical properties such as density, molar volume and oxygen packing density were calculated and discussed. FTIR and Raman spectral studies were performed to study the vibrational groups present in all the glasses. DSC analysis showed that the glass transition temperature (Tg) decreases with increase in Li2O content and the high thermal stability > 150 °C was observed for all glasses. Various optical parameters were calculated and variations in these values were correlated with structural changes in the glass network as revealed by FTIR and Raman studies. The estimated spin-Hamiltonian parameters of VO2+ from EPR spectra of glasses suggest that VO2+ is in octahedral site with tetragonal distortion.

Raman spectroscopic and theoretical studies on the structure of Ta (V) fluoro and oxofluoro complexes in molten FLiNaK

Combined with Raman spectroscopy and theoretical calculations, the tantalum fluoride and oxyfluoride ions in molten FLiNaK were studied. Firstly, the Raman spectra of K2TaF7 were recorded from 298 to 973 K and no structural evolution was observed. The coexistence of TaF72– and TaF83– anions was confirmed in K2TaF7 and molten FLiNaK-K2TaF7 mixtures. With the addition of Li2O (3 mol%), the terminal oxo ligands TaOF52– and TaOF63– were formed at the expense of TaF72– and TaF83– with the release of free F– ions, respectively. When the Li2O content increased to 13 mol%, two new oxyfluorides TaO2F2– and TaO2F32– were observed that contained two non-bridging oxygens. As the content of Li2O further increased to 40 mol%, insoluble solid tantalum oxide species like β-Ta2O5 was found, which indicates the transformation of intermediate oxyfluorides formed by the reaction of TaF72– and TaF83– fluorides with O2– in molten FLiNaK to oxides.

Effect of Li2O on the crystallization behavior of CaO-Al2O3-SiO2-Li2O-Ce2O3 mold slags

The effect of Li2O on the crystallization properties of CaO-Al2O3-SiO2-Li2O-Ce2O3 slags was investigated. With increasing the Li2O content, LiAlO2 and CaCeAlO4 were the main crystalline phases. LiAlO2 formed for the charge compensating of Li+ ions to [AlO45−]-tetrahedrons, and CaCeAlO4 formed as a result of the charge balance of Ce3+ ions, Ca2+ ions, and [AlO69−]-octahedrons. Increasing the content of Li2O to 10%, the crystallization temperature was the highest, and the incubation time was the shortest. The crystallization ability was strong due to the three factors of strengthening the interaction between ions and ion groups, decreasing the polymerization degree, and increasing the melting temperature. Further increasing the content of Li2O, the crystallization performance was obviously suppressed, because the melting temperature and the force between the cations and the anion groups decreased.