Alkali-metal Intercalation Compounds Research Articles

Facile synthesis, structure and physical properties of 3R-AxNbS2 (A = Li, Na)

Here we report the facile synthesis of alkali metal intercalation compounds AxNbS2 (A = Li, Na) through the reaction of bulk 3R phase of NbS2 with organometallic compounds in solution. Especially, the Na insertion compound of various compositions was obtained as a new polytype of AxNbS2 compared with the 2H phase reported previously. Upon intercalation the structure of the host was preserved, which was confirmed by XRD and HRTEM analysis. The interlayer distances for Li0.44NbS2 and Na0.87NbS2 were expanded by 0.187 Å and 0.938 Å as a result of Li and Na intercalation, respectively. The electrical transport properties were studied in the temperature range 4–298 K, exhibiting metallic conductivity and slight variation in the resistivity value in general. Interestingly, a minimum resistivity which was ascribed to the localized electrons in the crystal lattice emerged for all the investigated samples.

Superconductivity of alkali metal intercalated TiNBr with α-type nitride layers

TiNBr with α-type nitride layers (isostructural with FeOCl) was electron-doped by the intercalation of alkali metal (Li, Na, K, and Rb), which can be cointercalated with organic solvent molecules such as tetrahydrofuran (THF) and propylene carbonate (PC), expanding the basal spacing (d) up to 16 Å. All of the alkali metal intercalation compounds with and without cointercalation become superconductors with transition temperatures (Tc) up to 17.2 K. The Tc varies in a narrow temperature range against a wide range change of 0.1 < x < 0.46 in AxTiNBr. The Tc decreases linearly with the decreasing value of 1/d. The layer structured superconductors show a low anisotropy on the upper critical field (Hc2). These are characteristic features very similar to those found for the intercalation compounds of the Cl homolog TiNCl.

Polymorphism in Self-Assembled AB6 Binary Nanocrystal Superlattices

We report the formation and systematic struc-tural characterization of a new AB(6) polymorph with the body-centered cubic (bcc) symmetry in binary nanocrystal superlattices (BNSLs). The bcc-AB(6) phase, lacking any atomic analogue, is isomorphic to certain alkali-metal intercalation compounds of fullerene C(60) (e.g., K(6)C(60)). On the basis of the space-filling principle, we further tailor the relative phase stability of the two AB(6) polymorphs-CaB(6) and bcc-AB(6)-from coexistence to phase-pure bcc-AB(6), highlighting the entropic effect as the main driving-force of the self-organization of BNSLs. We also discuss the implication of surface topology studies and the observation of twinning and preferential orientation in bcc-AB(6) on the growth mechanism of BNSLs. Furthermore, the connection between the bcc-AB(6) phase and the (3(2).4.3.4) Archimedean tiling shows the promise of further exploration on the structural diversity (both periodic and aperiodic) in this emerging class of metamaterials. The identification and the ability to tune the relative phase stability of polymorphic structures provide a unique opportunity to engineer the interparticle coupling through controlled clustering and/or interconnectivity of sublattice in BNSLs with identical stoichiometry.

A New Intercalation Superconductor Mgx(PC)yZrNCl

A new superconducting layered nitride Mgx(PC)yZrNCl (PC: propylene carbonate) with x=0.3 has successfully been synthesized by an electrochemical Mg-intercalation technique in PC used as a solvent. From the powder X-ray diffraction measurement, PC molecules are expected to be co-intercalated with Mg. The magnetic susceptibility measurements have revealed the appearance of superconductivity with the superconducting transition temperature Tc∼15 K, which is the same as those in alkali-metal intercalation compounds AxZrNCl (A=Li, Na, K). The present Mgx(PC)yZrNCl is the first Mg-intercalated superconductor.

Electronic structure of cross-linked carbon nanotubes doped with alkali metals

Based upon ab initio density functional theory calculations, it has been predicted that bundles of small zigzag single walled carbon nanotubes can undergo spontaneous cross linking to form 2-dimensional layered structures. Analogous to graphite, these layered structures should provide a framework that allows intercalation of chemical species. Using density functional theory, we explore the possible structures of alkali metal intercalated cross-linked (5,0) nanotubes and calculate the electronic properties of these materials. We have found that the intercalated materials undergo substantial lattice expansion and that the metal atoms are largely ionized. The cross-linked (5,0) nanotube material and the alkali metal intercalation compounds are predicted to be metallic representing a substantial change in electronic properties relative to the semiconducting cylindrical (5,0) zigzag nanotubes.

Synthesis and characterization of SWNT-heavy alkali metal intercalation compounds, effect of host SWNTs materials

Singlewall carbon nanotubes (SWNTs) produced by electric-arc and laser ablation methods were characterized by X-ray diffraction before and after the reaction with alkali metals (M=K, Rb, and Cs). Reaction with annealed SWNTs gave MC 8 composition at saturation. The alkali metal lattice showed short range order incommensurate with graphene cylinders of SWNTs. X-ray diffractogram simulations have enabled the study of the influence of SWNTs structure on that of intercalation compounds. Chemically-purified bundles, constituted of open SWNTs, can be intercalated inside and between the tubes forming disordered structures. Annealed or pristine bundles were intercalated only between the tubes leading to short or long range ordered structure depending on host crystallinity and alkali metal (K, Rb or Cs). The expansion of the 2D SWNTs lattice after intercalation is comparable to graphite intercalation compounds. Some 2D arrangements of SWNTs and K atoms are proposed and discussed to reproduce XRD results. 13C NMR and ESR studies of annealed doped SWNTs emphasize the fact that the intercalation compounds of SWNTs are metallic.

A DFT study of hBN compared with graphite in forming alkali metal intercalation compounds

From the calculated results by B3LYP method of Density Function Theory (DFT), the difference in electron affinity between hexagonal boron nitride (hBN) and graphite, and the difference in electronic structures of their alkali metal intercalation compounds, show that it is difficult for hBN to be intercalated with metals.

Solid-State NMR Study of Hydrated Intercalation Compounds of Molybdenum Disulfide

Solid-state NMR has been used to study the local coordination environments of the protons and alkali metal cations in hydrated alkali metal intercalation compounds of MoS2, Ax(H2O)yMoS2 (A = Li, Na, K, Cs). The dynamic behavior of the water molecules, which are coordinated to the intercalated A+ cations, is consistent with an ordered quasi two-dimensional translational motion at room temperature. In Lix(H2O)yMoS2, the hydrated Li+ cations occupy two distinct sites in the van der Waals gap that are connected by dynamic processes. Partially random motions of the H2O molecules are activated at room temperature.

Structural analysis of fullerene and fulleride solids from synchrotron X-ray powder diffraction

Synchrotron-based X-ray powder diffraction has proved indispensable in the study of fullerene solids, their alkali metal intercalation compounds and chemical derivatives. Here we review some recent developments to which David E. Cox has made important material and intellectual contributions, not only in advancing the field of fullerenes but in helping to train a new generation of young scientists. Topics covered include finite vacancy concentrations in superconducting phases, estimates of the vacancy formation energies from temperature-dependent phase analysis, and the effects of alkali metal intercalation on orientational states, order-disorder transitions and superconductivity.

Disorder IN C60 Intercalation Compounds and Implications for Superconductivity

Abstract Alkali metal intercalation compounds of C60 have attracted a great deal of interest, due primarily to the existence of superconductivity in some members of the family but also to the richness of the binary phase equilibria versus metal concent, ration, temperature and hydrostatic pressure. The C60 host lattice itself exhibits novel structural and dynamical properties, many of which are associated with orientational ordering of the molecules [1]. The extent to which disorder of all kinds plays a role in phase equilibria and superconductivity of the doped phases is just beginning to be appreciated. Here I review briefly what is currently known.

Order and disorder in fullerene and fulleride solids

A review is given of crystal structures and order/disorder phenomena in the fullerene solids C 60, C 60O and C 70 and in the alkali metal intercalation compounds of C 60. Recent results on orientational melting and quenched orientational disorder in the pristine solids are summarized, and the effect of small perturbations on the quasi-spherical molecular shape are described. The intercalation properties of C 60 are discussed in the context of other host lattices such as graphite. The variety of orientational correlations in fullerenes and fullerides is rationalized in terms of competing contributions to the orientational potentials. Structural properties of alkali fullerides are correlated with electronic properties and superconductivity, and an updated binary phase diagram is described.

Compressibility of M3C60Fullerene Superconductors: Relation BetweenTcand Lattice Parameter

X-ray diffraction and diamond anvil techniques were used to measure the isothermal compressibility of K(3)C(60) and Rb(3)C(60), the superconducting, binary alkali-metal intercalation compounds of solid buckminsterfullerene. These results, combined with the pressure dependence of the superconducting onset temperature T(c) measured by other groups, establish a universal first-order relation between T(c) and the lattice parameter a over a broad range, between 13.9 and 14.5 angstroms. A small secondorder intercalate-specific effect was observed that appears to rule out the participation of intercalate-fullerene optic modes in the pairing interaction.

The Interaction of Graphite - Alkali Metal Intercalation Compounds with Water and Alcohols: Will the Graphite be Hydrogenated?

The Interaction of Graphite - Alkali Metal Intercalation Compounds with Water and Alcohols: Will the Graphite be Hydrogenated?

ChemInform Abstract: Preparation Methods for Alkali Metal Intercalation Compounds of Oxides and Chalcogenides

ChemInformVolume 20, Issue 33 Reviews ChemInform Abstract: Preparation Methods for Alkali Metal Intercalation Compounds of Oxides and Chalcogenides D. W. MURPHY, D. W. MURPHY AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this authorS. A. SUNSHINE, S. A. SUNSHINE AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this authorS. M. ZAHURAK, S. M. ZAHURAK AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this author D. W. MURPHY, D. W. MURPHY AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this authorS. A. SUNSHINE, S. A. SUNSHINE AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this authorS. M. ZAHURAK, S. M. ZAHURAK AT&T Bell Lab., Murray Hill, NJ 07974, USASearch for more papers by this author First published: August 15, 1989 https://doi.org/10.1002/chin.198933350Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume20, Issue33August 15, 1989 RelatedInformation

Lattice-dynamical model for graphite and its alkali-metal intercalation compounds.

The phonon-dispersion relations of graphite and the first-stage alkali-metal--graphite intercalation compounds have been calculated by a two-body carbon-carbon potential. In this proposed potential, in addition to the Born-Mayer constants A and \ensuremath{\rho}, two parameters for the stability of the graphite crystal along the a and c axes have been incorporated. Firstly, phonon dispersion in graphite has been investigated considering two neighbors within the plane and one neighbor between the planes. We have then extended this analysis to the evaluation of the phonon spectrum of first-stage potassium-graphite intercalation compound. Results obtained are in good agreement with the available experimental data.

Low-temperature specific heat of hydrogen-chemisorbed graphite-alkali-metal intercalation compounds.

The results of low-temperature specific-heat measurements are presented for hydrogen-chemisorbed ${\mathrm{C}}_{8}$M (M=K,Rb), to clarify the effects of dissolved hydrogen on its electronic and lattice vibrational properties. The density of states at the Fermi level is suppressed through a charge transfer from ${\mathrm{C}}_{8}$M to hydrogen which is stabilized in interstitial sites in the intercalate layers. This finding is consistent with the results of ESR and positron-annihilation measurements. The introduction of hydrogen increases the acoustic and optic phonon energies for ${\mathrm{C}}_{8}$${\mathrm{KH}}_{\mathrm{x}}$ (x0.1). The electronic effects of dissolved hydrogen are considered to be the cause of the increase. At the hydrogen-saturated concentration (${\mathrm{C}}_{8}$${\mathrm{KH}}_{2/3}$), the phonon energies are lowered by an increase in the effective mass of the intercalants due to the strong ionic coupling between K and H through bondings with hydrogen. In the case of the ${\mathrm{C}}_{8}$Rb system, the acoustic-phonon energies increase while the optic-phonon ones decrease through the introduction of small concentrations of hydrogen (x0.1). The effects of dissolved hydrogen on the superconductivity of ${\mathrm{C}}_{8}$${\mathrm{KH}}_{\mathrm{x}}$ are discussed using the specific-heat results.

Alkali metal intercalation in ternary and multinary compounds

The group-IV,-V and-VI transition metal dichalcogenides are able to rapidly and reversibly incorporate significant concentrations of alkali metal ions (intercalants) within their layer structures. Because of their unusual combination of rapid mobility and high chemical stability for the intercalant, some of the alkali-metal-intercalated dichalcogenides are attractive candidates for high-energy battery electrodes. The structural characteristics of the lithium- and sodium-intercalated TiS2 compounds, which are the most extensively investigated intercalated materials, are summarized. The chemical stability of intercalants is discussed, with an emphasis on the ternary-phase equilibria, electrochemicalcell voltage and intercalant interaction energies. Some recent investigations with multinary alkali metal intercalation compounds are then described.

Local density of unoccupied states in alkali metal intercalation compounds by photoyield spectroscopy

Partial photoyield measurements have been performed on the graphite intercalation compounds C 6Li and C 8K and on pure highly oriented pyrolytic graphite. These experiments probe the local unoccupied electron states on each type of site. It is found that C π ∗ states contribute to the density of states at E F in the intercalation compounds as expected, and that the empty Li2p and K3d states lie close to the respective vacuum levels but do not contribute to the density of states at E F.

Model for superconductivity in graphite intercalation compounds

The observed superconductivity in the stage-1 graphite---alkali-metal intercalation compounds (GIC's) is modeled using both graphite $\ensuremath{\pi}$ bands and intercalate $s$ bands. The anisotropy observed in the superconducting properties is explained in terms of the anisotropy of the Fermi surfaces of the GIC's.

Hydrogen in aromatics. III. Chemisorption of hydrogen in graphite–alkali metal intercalation compounds

The hydrogen chemisorption mechanism in the graphite–alkali metal intercalation compounds has been investigated by means of ESR and electrical resistivity under hydrogen atmosphere. In the first stage rubidium compound C8Rb, hydrogen molecules are dissociated into atoms which are stabilized in the interstices of Rb atoms in the gaps of the graphite layers. C8K has a two-stage hydrogen absorption. In the initial stage, the dissociated hydrogen atoms are transiently yielded and then, in the second stage, the formation of hydride ions H− takes place through the charge transfer from C8K to H. C8Cs shows no change in the ESR signal under hydrogen atmosphere. This finding suggests that its catalytic activity for an H–D exchange reaction is due to the surface activity. For the second stage compounds C24K and C24Rb, there exists a one-stage hydrogen absorption process, i.e., absorbed hydrogen directly becomes hydride ion H−. C24Cs shows no change in the ESR signal under hydrogen atmosphere. For the chemisorption activity, the order of the strength is K≳Rb≳Cs in both first and second stage compounds.