The lithium sodium silicide Li3NaSi6 and the formation of allo-silicon

Schnering, Hans‐Georg von; Schwarz, Martin; Nesper, Reinhard

doi:10.1016/0022-5088(88)90095-1

Cited by 54 publications

(57 citation statements)

References 25 publications

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“…The ring system in 2 contains components which are reminiscent of monoclinic GaTe (12), or SiAs (13), KSi As (14), and Li NaSi (15). The structure of GaTe and SiAs are isotypic and contain tetrahedra centered about the Ga or Si atoms formed by three Ga-Te bonds and one Ga-Ga bond, or three Si-As bonds and one Si-Si bond, respectively.…”

Section: Figmentioning

confidence: 99%

“…One potassium atom, K(3), is four-coordinate with a see-saw geometry. There are three potassium atoms which are five-coordinate, K(5), K (7), and K (15). Potassium atoms K(5) and K (15) each have a long contact with one potassium atom (3.75 (2) and 3.70 (2) A s , respectively).…”

Section: Crystal Structuresmentioning

confidence: 99%

“…2, which shows a ball and stick representation of a section of one layer in compound 1, as well as the numbering scheme used for the indium, germanium, and arsenic atoms. The row of Ge As dimers contains a periodic substitution of two InAs tetrahedra which are centered about In (15) and In(16). The InAs tetrahedra formed from In(1) and In(9), In(4) and In(5), In (7) and In (8), and those from In (10) and In (12) share a common edge.…”

Section: Crystal Structuresmentioning

confidence: 99%

See 2 more Smart Citations

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Shreeve‐Keyer¹,

Haushalter²,

Lee

et al. 1997

Journal of Solid State Chemistry

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Section: Figmentioning

confidence: 99%

Section: Crystal Structuresmentioning

confidence: 99%

Section: Crystal Structuresmentioning

confidence: 99%

See 1 more Smart Citation

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Shreeve‐Keyer¹,

Haushalter²,

Lee

et al. 1997

Journal of Solid State Chemistry

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“…We note that the polycrystalline ternary silicide compound Li 3 NaSi 6 (ref. 41) was synthesized by this approach when using LiCl and NaSi 16 Si 136 . Thermal ellipsoids for K (8b) and Na (16c) are 90% probability.…”

Section: View Article Onlinementioning

confidence: 99%

Rapid crystal growth of type-II clathrates A₈Na₁₆Si₁₃₆ (A = K, Rb, Cs) by spark plasma sintering

Dong

Nolas

2015

CrystEngComm

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Single crystal type-II clathrates A 8 Na 16 Si 136 (A = K, Rb, and Cs) were grown from NaSi and alkali metal halides by spark plasma sintering (SPS). Single crystal structure refinements indicate that K atoms at the 8b crystallographic site are partially occupied ĲK 5.8Ĳ1) Na 16 Si 136 ) while Rb in Rb 8 Na 16 Si 136 and Cs in Cs 8 Na 16 Si 136 are fully occupied. Our results indicate that SPS can be employed in topochemical ion exchange reactions, thus allowing for the rapid synthesis of single crystals of multinary intermetallic phases that cannot be accessible by traditional crystal growth techniques.Inorganic clathrates based on group 14 elements have attracted attention due to their interesting structural and physical properties, for example very low thermal conductivities, 1-3 tunable electrical properties and band gaps with modification of composition, 4,5 and second-order ferromagnetic phase transitions. 6-8 As a result, they are of interest for a variety of potential technological applications, including solid state energy conversion, 1-3,9 photovoltaics, 10,11 magnetocalorics, 12-14 superconductivity, 15-17 and as the anode for Li-ion batteries. [18][19][20] Due to this scientific interest and technological importance an understanding of the fundamental structural and physical properties of inorganic clathrates is essential. In order to achieve this goal various synthetic techniques have been employed to obtain stable or metastable compositions that are not accessible by conventional solid state reaction or single-crystal growth methods. These include soft chemical routes (chemical oxidation), 21-23 kinetically controlled thermal decomposition, 24,25 high-temperature high-pressure synthesis, 26,27 and spark plasma sintering (SPS). 28,29 Among the synthetic approaches described above, SPS is unique in that it applies a pulsed DC current to the specimen through a die assembly that is between two electrodes under uniaxial pressure. SPS processing is well established for the consolidation of ceramics, polymers, semiconductors, and nanocomposites due to the fast heating rates and uniform heating through the specimen inside the die assembly. [30][31][32][33][34][35][36] Recently crystal growth of binary type-I and -II clathrates, Na 8 Si 48 and Na 24 Si 136 , by SPS was achieved. 28,29 In this report we demonstrate that ternary type-II clathrate single crystals can be synthesized via ion-exchange and electrochemical oxidation-reduction (redox) reactions between NaSi and ACl (A = K, Rb, Cs) using SPS. This approach will also be of interest for the synthesis and crystal growth of other intermetallic or metastable ternary, and potentially quaternary, compounds.Single crystals of three type-II clathrates, K 5.8Ĳ1) Na 16 Si 136 , Rb 8 Na 16 Si 136 , and Cs 8 Na 16 Si 136 , were synthesized by SPS. The NaSi precursor along with each alkali-metal chloride were ground together in a 1 : 1 mass ratio and the resulting mixture was loaded in a graphite die assembly. Tantalum foil was placed between the precursor mixture ...

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“…In contrast to Si-based open frameworks phases (clathrates), 30-32 the reaction of dense NaSi and KSi with Li has not yet been reported, to our knowledge, and only a very few Li-(Na,K)-Si ternary phases are mentioned. 34 Interestingly, the pre-lithiation of germanium was recently found to ease its post reaction with Na in electrochemical cells and to improve its reversibility. 35 In light of these aspects, we here describe the controlled room temperature electrochemical reaction of NaSi and KSi phases with lithium through the use of various techniques such as in-situ X-ray diffraction, elemental analysis and thermal analysis.…”

mentioning

confidence: 99%

Electrochemical Reactivity of KSi and NaSi Zintl Phases with Lithium

Seznéc

Senguttuvan

Larcher

et al. 2015

ECS Electrochemistry Letters

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The electrochemical reactions of NaSi and KSi Zintl phases with lithium (0-2.5 V) proceed very differently. Na/K is partially removed on first oxidation with a complete amorphization for NaSi or growth of a new crystallized K x Si phase for KSi. Upon discharge, metallic K is partially extruded and a Li-K-Si (Li 15 Si 4 -type) phase is formed. For NaSi, metallic Na is also chased on discharge but crystallization of Li-Na-Si (Li 15 Si 4 -type) phase is delayed at the second discharge. The amorphization of Li 15 K x Si 4 proceeds through a ∼0.40 Volts charge plateau but crystallized Li 15 Na x Si 4 does not show this feature and electrochemically behaves similarly to amorphous Li x Si.The design of high energy density electrochemical storage devices requires either or both high voltage difference ( E) and large amounts of exchanged species (i.e. large capacities) between the two electrodes. High E can be achieved through the use of highly electropositive metals (alkali, alkaline earth) whose corresponding monovalent or bivalent ions are either reversibly hosted in intercalation compounds (e.g. Li-ion technology) or electroplated (e.g. Li-polymer technology) during the charging step. To date, graphitic powders are the state-of-the-art intercalating material but alloys and alloying reactions have also been intensively investigated for decades with great performance improvements and some enthusiastic industrial announcements, but very slim commercialization success so far (MatsushitaWood's metal-80's, Fuji-Stalion-1995, Sony-Nexelion-2005.For Li-based systems, silicon is the most appealing candidate for Li-alloying element because it scores the highest discharge gravimetric (3579 mAh/g of Si) and volumetric (8330 mAh/cm 3 of Si) capacities, both ranking around ten times higher than those of carbon (Li 15 Si 4 1 vs. LiC 6 2 ) with a reaction taking place at very low potential (<200 mV vs. Li + /Li • ). This alloying process comes with very large volume changes 3 (≈275% for Si → Li 15 Si 4 ) leading to particle displacement, loss of contact/cohesion in composite electrodes, and formation of reactive surfaces, resulting in a poor cycle life. These major issues triggered many tackling approaches such as the use of small particles, 4,5 the confinement in active or inactive buffering matrices, 6-9 the use of suited polymeric binders, 10-15 thin films, 16-18 the application of specific cycling conditions, 19 and tuning the electrode porosity/formulation. Crystallized silicon undergoes a progressive amorphization during its first lithiation (a-Li x Si), but a crystallized phase can be spotted at very low voltage (c-Li 15 Si 4 ) and then back converted to amorphous a-Li x Si during charge.

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The lithium sodium silicide Li3NaSi6 and the formation of allo-silicon

Cited by 54 publications

References 25 publications

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Rapid crystal growth of type-II clathrates A₈Na₁₆Si₁₃₆ (A = K, Rb, Cs) by spark plasma sintering

Electrochemical Reactivity of KSi and NaSi Zintl Phases with Lithium

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The lithium sodium silicide Li3NaSi6 and the formation of allo-silicon

Cited by 54 publications

References 25 publications

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Rapid crystal growth of type-II clathrates A8Na16Si136 (A = K, Rb, Cs) by spark plasma sintering

Electrochemical Reactivity of KSi and NaSi Zintl Phases with Lithium

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Rapid crystal growth of type-II clathrates A₈Na₁₆Si₁₃₆ (A = K, Rb, Cs) by spark plasma sintering