Ionic conductivity in single-crystal LiAlSi2O6: influence of structure on lithium mobility

Welsch, Anna-Maria; Murawski, Dawid; Prekajski, Marija; Vulić, Predrag; Kremenović, Aleksandar

doi:10.1007/s00269-015-0732-2

Cited by 21 publications

(8 citation statements)

References 22 publications

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“…[11][12][13] Like b-spodumene, g-spodumene is absent in nature but it can be produced relatively easily from melts. 14 It has hexagonal symmetry with Si and Al occupying the centre of tetrahedrons; its density is 2400 kg m À3 . 15 Experimental studies have shown that the Li + conductivity of g-spodumene is several orders of magnitude higher than that of b-spodumene (singlecrystal and polycrystalline) and a-spodumene.…”

Section: Introductionmentioning

confidence: 99%

“…15 Experimental studies have shown that the Li + conductivity of g-spodumene is several orders of magnitude higher than that of b-spodumene (singlecrystal and polycrystalline) and a-spodumene. 14 The phase diagram for the spodumene polymorphs is not well known. Laboratory studies indicate an a-b inversion temperature in the range 700 to 800 1C 16,17 while a recent computational study reported 800 AE 80 1C.…”

Section: Introductionmentioning

confidence: 99%

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In situsynchrotron XRD analysis of the kinetics of spodumene phase transitions

Moore

Mann

Montoya

et al. 2018

Phys. Chem. Chem. Phys.

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The phase transition by thermal activation of natural α-spodumene was followed by in situ synchrotron XRD in the temperature range 896 to 940 °C. We observed both β- and γ-spodumene as primary products in approximately equal proportions. The rate of the α-spodumene inversion is first order and highly sensitive to temperature (apparent activation energy ∼800 kJ mol-1). The γ-spodumene product is itself metastable, forming β-spodumene, with the total product mass fraction ratio fγ/fβ decreasing as the conversion of α-spodumene continues. We found the relationship between the product yields and the degree of conversion of α-spodumene to be the same at all temperatures in the range studied. A model incorporating first order kinetics of the α- and γ-phase inversions with invariant rate constant ratio describes the results accurately. Theoretical phonon analysis of the three phases indicates that the γ phase contains crystallographic instabilities, whilst the α and β phases do not.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In situsynchrotron XRD analysis of the kinetics of spodumene phase transitions

Moore

Mann

Montoya

et al. 2018

Phys. Chem. Chem. Phys.

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“…Lithium is of particular interest in the battery industry due to its high electrochemical potential and high energy density, and in the ceramics industry because of the low thermal expansion of lithium aluminosilicates. , One of the primary sources of high-grade lithium is spodumene (LiAlSi 2 O 6 ), an aluminosilicate that exhibits considerable polymorphism due to sensitivity of the structure to changes in temperature, pressure, and mechanical treatment …”

Section: Introductionmentioning

confidence: 99%

“…Thus, in practice, β-spodumene is the active phase for lithium extraction under acidic conditions. Heat treatment of α-spodumene at atmospheric pressures above 973 K induces a phase transition to the β-spodumene polymorph. − The phase change from α- to β-spodumene is of a reconstructive nature, occurring irreversibly with a change in the crystallographic features. − Heat treatment of mechanically activated α- or β-spodumene between 973 and 1173 K at atmospheric pressure results in a γ-spodumene polymorph, which is metastable after further heating to above 1173 K, forming β-spodumene. ,, …”

Section: Introductionmentioning

confidence: 99%

Effect of the Local Atomic Ordering on the Stability of β-Spodumene

2016

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This study focuses on the relative energetic stability of β-spodumene configurations with different atomic ordering, evaluated using electronic structure methods based on static periodic density functional theory. We found that β-spodumene configurations with a framework containing exclusively Al-O-Si linkages are energetically the most stable, consistent with the aluminum avoidance principle. A correlation between the interstitial sites occupied by lithium and the stability of the configuration was established: highly stable configurations contain greater proportions of lithium associated with the edges of AlO4 tetrahedrons. The identified low-energy configurations have a band gap of ∼4.8 eV, and similar electronic band structures and densities of states. Both the PBE and PBEsol functionals predict small differences in the relative stabilities of the different configurations of β-spodumene. However, only PBEsol is able to reproduce the experimentally observed stability differences between α-spodumene and β-spodumene. β-Spodumene is the preferred polymorph at high temperatures, with the PBEsol inversion temperature from α- to β-spodumene predicted to occur at 1070 K.

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“…Perpendicular to the c axis, the AlO 6 units and SiO 4 tetrahedra act as barriers between consecutive lithium sites . The conventional process of extracting lithium from spodumene involves calcination of α-spodumene to obtain β-spodumene that is subsequently roasted with sulfuric acid at 250 ° C and water-leached. , Tetragonal β-spodumene has a more open structure that is dominated by interlocking five-membered rings of (Si, Al) tetrahedra with lithium atoms in interstitial positions (Figure b).…”

Section: Introductionmentioning

confidence: 99%

Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

et al. 2021

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The conventional process of lithium extraction from α-spodumene (LiAlSi 2 O 6 ) is energy-intensive and associated with high byproduct management cost. Here, we investigate an alternative process route that uses potassium sulfate (K 2 SO 4 ) to extract lithium while producing leucite (KAlSi 2 O 6 ), a slow release fertilizer. Presenting the first-ever in situ record of the reaction of α-spodumene with potassium sulfate, we use synchrotron X-ray diffraction (XRD) and differential scanning calorimetry (DSC) to document the reaction sequence during prograde heating. From 780 °C, we observe a broad endothermic DSC peak, abnormal expansion of the α-spodumene structure, and an increase in α-(Li, K)-spodumene peak intensity during heating with potassium sulfate, indicative of the exchange between lithium and potassium in the spodumene structure. When 11 ± 1% K occupancy in the M2 site of α-(Li, K)-spodumene is reached, the mechanism changes from ion exchange to a reconstructive transformation of α-(Li, K)-spodumene into leucite, evidenced by a decrease in α-spodumene and potassium sulfate abundance concurring with formation of leucite over a narrow temperature range between 850 and 890 °C. The increasing background intensity in synchrotron XRD above 870 °C suggests that a lithium sulfate-bearing melt starts to form once >90% of α-spodumene has been converted during the reaction. This fundamental understanding of the reaction between α-spodumene and potassium sulfate will enable future development of lithium extraction routes using additives to significantly decrease energy intensity and to produce marketable byproducts from α-spodumene.

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Ionic conductivity in single-crystal LiAlSi2O6: influence of structure on lithium mobility

Cited by 21 publications

References 22 publications

In situsynchrotron XRD analysis of the kinetics of spodumene phase transitions

In situsynchrotron XRD analysis of the kinetics of spodumene phase transitions

Effect of the Local Atomic Ordering on the Stability of β-Spodumene

Two-Step Reaction Mechanism of Roasting Spodumene with Potassium Sulfate

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