Thermochemical investigation of lithium borate glasses and crystals

Abstract

Lithium borate (LB) glasses and crystals with x = Li/(Li + B) = mole fraction of Li 2 O of 0.2-0.5 have been synthesized by the quenching method. The thermodynamics of these materials were analyzed by high-temperature oxide melt solution calorimetry. The formation enthalpies from oxides of glasses range from −33.6 to −67.3 kJ/mol and those of crystals range from −42.1 to −77.4 kJ/mol, where compositions are given on the basis of one mole of (Li 2 O + B 2 O 3 ). The formation enthalpies of both glasses and crystals become more negative with increasing Li 2 O mole fraction up to 0.5. The enthalpies of formation of glasses can be fit over the entire composition range (0 < x < 1) by a quadratic polynomial). The vitrification enthalpies were derived for x = 0.2 to 0.5 and ranged from 8.5 to 17.6 kJ/mol. The main factors controlling energetics are the strongly exothermic acid-base reaction between the network former (B 2 O 3 ) and the network modifier (Li 2 O) and the formation of tetrahedrally coordinated boron in the glasses and crystals.

Effects of Al:Si and (Al + Na):Si ratios on the properties of the international simple glass, part I: Physical properties

“…The glasses ISG‐C, ISG‐A00, ISG‐A12, and ISG‐A22, having Na 2 O content around 14 mol% (Table 2), show almost equal enthalpies of formation (Figure 4C‐D). A similar trend between the mole percentage of one other basic alkali metal oxide, Li 2 O, and exothermic enthalpies of formation has been recently reported in the high‐temperature solution calorimetric study of lithium borate glasses 85 . The variation in ΔH° f,ox with composition show no evidence of anomalies that could be related to phase separation or crystallization.…”

“…A similar trend between the mole percentage of one other basic alkali metal oxide, Li 2 O, and exothermic enthalpies of formation has been recently reported in the high-temperature solution calorimetric study of lithium borate glasses. 85 The variation in ΔH°f ,ox with composition show no evidence of anomalies that could be related to phase separation or crystallization. further toward the higher wave numbers of ISG-C compared to ISG-A00 by ~30 cm −1 which is likely caused by immiscible phase separation.…”

Lithium Borates from the Glass to the Melt: A Temperature-Induced Structural Transformation Viewed from the Boron and Oxygen Atoms

“…Both processes have opposite effects on the melt density: the [3] B → [4] B conversion when Li 2 O is added tends toward a densification of the melt, whereas the formation of NBOs leads to a depolymerization of the borate network and consequently to an increase in the melt volume. A change of slope of the density at 800 °C as a function of concentration is observed in this concentration domain, where the vitrification enthalpy reaches its maximum value …”

“…A change of slope of the density at 800 °C as a function of concentration is observed in this concentration domain, where the vitrification enthalpy reaches its maximum value. 51 4.4.3. Domain 3 (45−70 mol % Li 2 O).…”

Sol/Antisolvent Coating for High Initial Coulombic Efficiency and Ultra-stable Mechanical Integrity of Ni-Rich Cathode Materials

“…39 The raw LiBO 2 powder is also confirmed to be a typical crystalline LiBO 2 sample rather than the glass-LiBO 2 , as no exothermic peak for glass transition is detected in the DSC curve (Figure S7b). 40 Another HRTEM image of LiBO 2 -coated NCM is presented in Figure 4c, in which the lattice spacing of 0.4798 nm is defined for the (003) plane of NCM bulk, while a NiO-like rock-salt phase (Fm3̅ m) with interplanar spacings of 0.235 and 0.288 nm with an angle of 120°for ( 200) and (111) planes is also observed between the top of the bulk layered phase and LiBO 2 coating. Such a new rock-salt phase is clearer with nearly 2.5 nm thickness as shown in the enlarged HRTEM image in Figure S8.…”