Determination of temperature and enthalpy of melting of alkali disilicates by differential calorimetric analysis

Boivin, Paul A.; Berthelay, J; Blanc, Y.; Coulet, A.L.; Castanet, R.

doi:10.1007/bf00595754

Cited by 9 publications

(2 citation statements)

References 3 publications

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“…36,37 The gels also exhibit prominent diffractions at low 2y values with spacings that range from 11.90 Å (7.412y) at Na/Si5 0.30-8.44 Å (10.4812y) at Na/Si5 1.52. These peak positions are very similar to the basal diffractions of layered structure materials such as clay minerals, tobermorite, 38 and alkali disilicates, 39 and indicate the presence of reasonably well-ordered layer structures, although these structures do not have to constitute the entire sample. The 29 Si MAS NMR data discussed below support this conclusion.…”

Section: (1) Gel Synthesis and Compositionsupporting

confidence: 53%

Structural Investigations of Alkali Silicate Gels

Hou

Kirkpatrick

Struble

et al. 2005

Journal of the American Ceramic Society

117

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Investigation of a series of synthetic alkali silicate gels and gels produced by the alkali silica reaction (ASR) in field concrete using 29Si NMR spectroscopy, X‐ray diffraction, and bulk chemical analysis shows that local structures of the synthetic and field gels are quite similar. The most abundant Si sites for the field and synthetic gels with similar compositions have Q3 polymerization, and the number of non‐bridging oxygens per Si is similar for these samples. These samples also yield a basal X‐ray diffraction peak near 8–12 Å, suggesting that the structure is dominated by sheet‐like units, consistent with the dominant Q3 polymerization. Calculations based on the relative site abundances of the sites observed by 29Si NMR and the bulk chemical compositions indicate that there is insufficient alkali to charge‐balance all the non‐bridging oxygens and that there is a significant concentration of Si–OH linkages. The results provide strong support for the basic structural concepts of the so‐called kanemite model for ASR gel proposed by Wieker and coworkers, although the overall gel structure is likely to be more complex.

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Section: (1) Gel Synthesis and Compositionsupporting

confidence: 53%

Structural Investigations of Alkali Silicate Gels

Hou

Kirkpatrick

Struble

et al. 2005

Journal of the American Ceramic Society

117

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“…The data for invariant reactions calculated with the thermodynamic parameters optimized in the present work are compared with temperatures experimentally determined by different methods like quenching method from [10,54], DTA from [11,12,[54][55][56], drop calorimetry from [35], KEMS from [50], DSC from [41,57] and assessment from [15] in Table 6. Results of calculations for the eutectic reaction (Liq ↔ Li 4 SiO 4 + Li 2 SiO 3 ) are almost 30 K higher than our experimental value of 1289K obtained by DTA.…”

Section: Phasementioning

confidence: 99%

Critical Experiments and Thermodynamic Modeling of the Li2O-SiO2 System

de Abreu,

Fabrichnaya

2024

Solids

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Phase equilibria studies were performed in the Li2O-SiO2 system for heat-treated samples using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The temperature of the eutectic reaction (Liq ⇌ Li4SiO4 + Li2SiO3) was experimentally determined at 1289 K using Differential Thermal Analysis (DTA). No evidences of the Li6Si2O7 formation was found by the experimental investigation and therefore, it was not considered. Heat capacity of the Li8SiO6 phase was measured using Differential Scanning Calorimetry (DSC). Solid phases of the Li2O-SiO2 system were described as stoichiometric compounds and liquid phases by two-sublattice partially ionic liquid model. Four stoichiometric intermediate compounds were considered to be stable (Li8SiO6, Li4SiO4, Li2SiO3 and Li2Si2O5). The polymorphic transformation in Li2Si2O5 phase was accounted and the metastable liquid miscibility gap on SiO2-rich side was reproduced. The calculated phase diagram satisfactorily agrees with the experimental phase equilibria as well as calculated thermodynamic properties reproduces experimental values within uncertainty limits.

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Stability of Crystalline Compounds in Slag Systems Mainly Composed of Li2O-SiO2-CaO-MnOx

Abreu,

Schnickmann,

Chakrabarty

et al. 2024

JOM

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The challenge of obtaining sufficient raw materials is a major concern when it comes to extracting lithium from spent lithium-ion batteries. One way to address this is through pyrometallurgical processing, which leaves undesirable elements such as lithium, aluminum and manganese in the slag. The engineered artificial minerals approach focuses on the effective recovery of critical elements. Different slag systems have been studied in the literature, and understanding the phase relationships in the $$\text {Li}_2{\text {O}}$$ Li 2 O -$$\text {SiO}_2$$ SiO 2 -CaO-$$\text {MnO}_x$$ MnO x system can lead to optimization of the recycling process. In this context, the stability of undesirable silicates can affect the maximum separation of Li from the slag. In order to contribute to the development of the Li recycling process, the stability of crystalline compounds was experimentally investigated in the present work for different slag compositions. The melted and solidified microstructures were characterized by SEM/EDX, EPMA, and XRD. Phase diagram data of binary and ternary systems were used to describe the solidification paths. As a result of solidification, crystals of $$\text {Li}_{2}\text {SiO}_{3}$$ Li 2 SiO 3 and $$\text {LiMnO}_2$$ LiMnO 2 were observed in a matrix consisting of $$\text {Ca}_{3}\text {Si}_{2}\hbox {O}_{7}$$ Ca 3 Si 2 O 7 and $$\text {CaSiO}_{3}$$ CaSiO 3 .

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Determination of temperature and enthalpy of melting of alkali disilicates by differential calorimetric analysis

Cited by 9 publications

References 3 publications

Structural Investigations of Alkali Silicate Gels

Structural Investigations of Alkali Silicate Gels

Critical Experiments and Thermodynamic Modeling of the Li2O-SiO2 System

Stability of Crystalline Compounds in Slag Systems Mainly Composed of Li2O-SiO2-CaO-MnOx

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