Solid Halides Research Articles

Heat Capacity of Solid Halide Eutectics and Their Enthalpy at Melting Point

The isobaric heat capacity of solid eutectic mixtures LiCl-KCl-CsCl, LiBr-CsBr and LiBr-KBr-CsBr was investigated from room temperature up to melting point. The molar heat capacity of all mixtures under study was found to be close to the additive sum of that of pure salts. The heat accumulated up to melting temperature is directly dependent on the melting point.

Fast Li-ion Conductor of Li3HoBr6 for Stable All-Solid-State Lithium–Sulfur Battery

Rare-earth (RE) solid-state halide electrolytes have been extensively studied recently in the field of lithium (Li) ion all-solid-state batteries (ASSBs) due to their excellent electrochemical performances. Herein, a new RE-based solid halide electrolyte Li3HoBr6 (LHB) has been synthesized and exhibits high Li ion conductivity up to mS cm-1 at room temperature. Theoretical calculations have identified four different Li ion migration pathways, in which the out-of-plane pathways are much more favorable than the direct in-plane pathways. In addition, LHB has a wider electrochemical window in comparison to a sulfide solid electrolyte and good deformability. The LHB-based Li-sulfur ASSB assembled by cold pressing can exhibit good cycling stability with high Coulombic efficiency, which shows that LHB has potential application in ASSBs.

(Invited) Solid Halide Electrolytes for All-Solid-State Lithium Ion Batteries

In order to realize all-solid-state batteries (ASSBs) with high energy density and high-rate charging/discharging capability that surpass conventional LIBs, development of solid electrolytes (SEs) is one of the utmost remaining issues. The difficulty is that SEs need to satisfy stringent requirements particularly for large scale applications; not only high ionic conductivity, but also high electrochemical stability, chemical stability, and deformability. However, neither sulfide nor oxide SEs satisfy all these requirements by themselves so far.Here, we propose that, considering the electronic and chemical nature of halide anions, halide solid electrolytes (HSEs) have potential to satisfy all the above requirements, and demonstrated that HSEs are indeed suited as an SE material for ASSB application [Ref].The lithium ionic conductivity of cold-pressed powders of the HSEs we developed surpassed 1 mS/cm at room temperature without any additional grain-boundary resistance. Such high ionic conductivity was realized even with close-packed anion sublattices whose ion pathways are unlike those of sulfide or oxide SEs, indicating that the design consideration for ionic conductors varies depeding on the material systems. The bulk-type ASSBs using these new HSE materials exhibited excellent charge/discharge performance with 4 V class cathode active materials without any extra coating; the initial coulomb efficiency over 94% and low interfacial resistance to be less than 10 Ωcm2, indicating high oxidation stability of HSE materials. Moreover, by appropriate selection of cation/anion pairs, electrochemical stability of HSE can be improved so that HSE can work with the anode active materials with Li-metal potential such as graphite.All these characteristics of halide materials clearly indicate that HSEs are promising candidate for ASSB application, in addition to sulfides and oxides, for large scale deployment.[Ref] T. Asano et al., Adv. Mater. 2018, 30, 1803075.

Impurity Composition of High-Purity Solid Halides

In this paper, we discuss general aspects of the impurity composition of high-purity solid halides, which are exemplified by an array of samples in the Permanent Exhibition–Collection of Extrapure Substances. We estimate the average and total concentrations of elemental impurities in the purest samples and assess the contributions of individual impurity classes to the total impurity concentration, which makes it possible to more accurately characterize the impurity composition of solid halides and statistic characteristics used to describe it.

Solid Halide Electrolytes with High Lithium-Ion Conductivity for Application in 4 V Class Bulk-Type All-Solid-State Batteries.

New lithium halide solid-electrolyte materials, Li3 YCl6 and Li3 YBr6 , are found to exhibit high lithium-ion conductivity, high deformability, and high chemical and electrochemical stability, which are required properties for all-solid-state battery (ASSB) applications, particularly for large-scale deployment. The lithium-ion conductivities of cold-pressed powders surpass 1 mS cm-1 at room temperature without additional intergrain or grain boundary resistances. Bulk-type ASSB cells employing these new halide solid electrolyte materials exhibit coulombic efficiencies as high as 94% with an active cathode material of LiCoO2 without any extra coating. These superior electrochemical characteristics, as well as their material stability, indicate that lithium halide salts are another promising candidate for ASSB solid electrolytes in addition to sulfides or oxides.

High temperature (35)Cl nuclear magnetic resonance study of the LiCl-KCl system and the effect of CeCl3 dissolution.

This paper examines the dynamics of the LiCl-KCl system over a range of temperatures in order to understand the local structure surrounding chlorine, which is the common ion in these systems, during molten salt pyro-processing. Chlorine-35 nuclear magnetic resonance (NMR) is sensitive to the local environments of the resonant nuclei and their motion on a diffusive timescale. Thus, it is a good probe of the atomic scale processes controlling the viscosities, diffusivities and conductivities of these molten salts. The average isotropic chemical shifts (((35)Cl)δ) and spin-lattice relaxation times (T1) of (35)Cl in (Li,K)Cl salt mixtures have been obtained over a compositional range of 0-100 mol% KCl with an interval of 10 mol% using high temperature nuclear magnetic resonance (NMR) spectroscopy from room temperature up to 890 °C. The ((35)Cl)δ in the two end member salts are consistent with the cation-anion radius ratio as previously measured on the solid halides and the average radius ratio of cation to anion, can be used to explain the variation of ((35)Cl)δ with composition. The quadrupolar interaction is found to be responsible for the spin-lattice relaxation of the (35)Cl, and the activation energies for T1 relaxation have been obtained for all compositions. The measured T1 ((35)Cl) activation energies do not vary linearly with composition and peak at 50% KCl, which also coincides with the Chemla point for this system. They also are in good agreement with the values from equivalent conductivity measurements. To investigate the response of the system to solutes, 8 wt% of CeCl3 was added to the pure LiCl as a surrogate actinide. The shift induced was 120 ppm and the activation energy for the T1 ((35)Cl) increased by a factor of four. This is a promising preliminary result for probing the effect of actinide dissolution on the dynamics of these pyro-processing salts.

Reversible Anion Exchange Reaction in Solid Halide Perovskites and Its Implication in Photovoltaics

Anion exchange reaction is a particularly versatile tool for the synthesis of a large class of nanomaterials. Here we report a low temperature, fast, reversible anion exchange reaction in halide perovskite thin film. Although processed in the solid-state phase, the exchanged hybrid perovskite shows good quality in terms of morphology conservation, phase transformation, and homogeneous composition. The easily exchanged reaction during the crystallization process suggests the robust nature of the Pb–CH3NH3 framework and high diffusion ability of halide ions in the perovskite lattice. Furthermore, we show its application in perovskite solar cells; we find that the anion exchange reaction does not induce any remarkable defects resulting from the lattice transformation and morphology reconstruction. In some case, the beneficial exchange of halide species involving simultaneous displacement reaction and crystallization can be used to improve the perovskite solar cell performance. Our work provides new physical insight into understanding the perovskite formation mechanism and the ionic behavior in the perovskite.

The effect of fluid salinity on infiltration-driven contact metamorphism of carbonate rocks

Calculated phase equilibria involving minerals and H2O–CO2–NaCl fluid lead to predictions of how infiltration of rock by H2O–NaCl fluids with XNaCl in the range 0–0.3 (0–58 wt% NaCl) drives the reactions calcite + quartz = wollastonite + CO2 and dolomite = periclase + calcite + CO2. Calculations focus on metamorphism in four aureoles that together are representative of the normal P–T conditions and processes of infiltration-driven contact metamorphic reactions. The effect of salinity on the spatial extent of oxygen isotope alteration was also computed. The time-integrated input fluid flux (q°) that displaces the mineral reaction front an increment of distance along the flow path always increases with increasing XNaCl. For input fluids with salinity up to approximately five times that of seawater (XNaCl ≤ 0.05), values of q° required to explain the spatial extent of decarbonation reaction are no more than 1.1–1.5 times that computed assuming the input fluid was pure H2O. For more saline fluids, values of q° may be up to 1.4–7.9 times that for pure H2O. Except for reaction in the presence of halite and vapor (V), infiltration of H2O–NaCl fluids expands the region of oxygen isotope alteration relative to the size of the region of mineral reaction. The expansion is significant only for saline fluids with XNaCl ≥ ~0.1. Immiscible fluid phase separation and differential loss of the liquid (L) or V phase from the mineral reaction site increases the amount of reactive fluid required to advance the mineral reaction front compared to conditions under which equilibration of minerals and fluid is attained with no loss of L or V. Decarbonation reactions driven by infiltration of fluids with even modest seawater-like salinity can explain the occurrence of salt-saturated fluid and solid halide inclusions in contact metamorphosed carbonate rocks.

VACUUM ULTRAVIOLET ABSORPTION SPECTRA OF SOLID HYDROGEN HALIDES

Absorption spectra of solid HCl, HBr and HI films deposited on LiF single crystals cooled at 103–104 K and those annealed have been obtained in the 4–11.5 eV region. The first peaks found around the absorption edges correspond to the first bands (dissociative) in isolated molecules, so that they are regarded as Frenkel exciton peaks. The spectral feature of as-deposited films changed after annealing irreversibly, which suggests the structural transition from an amorphous phase to a crystalline phase in HCl and HBr. In HI, it was revealed that the first band in the gaseous phase consists of three components. The broad structures found above the first peaks do not resemble the structures of the isolated molecules in the same energy region which consist of many lines. The band structures of solid hydrogen halides seem to resemble those of sodium halide crystals and solid rare gases.

Growth of HPHT diamonds in alkali halides: Possible effects of oxygen contamination

Abstract We carried out experiments of diamond growth in several alkali halides under HPHT conditions of 6 GPa and 1400–1620 °C for 5 h in order to determine whether the halides are active agents in the conversion of graphite to diamond. Growth layers with an order of 1 μm in thickness were detected on diamond seed crystals embedded in the halides. The diamond growth layers were formed even in solid halides, as well as in molten halides. When NaCIO 3 was added to the halides, the growth rate increased drastically. This result indicates that oxygen which contaminates the halides affects the diamond growth, even in the case without intentionally introducing oxygen into the halides, and we propose a model of the diamond growth in the carbon-halides systems that carbon atoms are transported as oxide in the halide media and precipitate on the seed crystal.

On the structural data of Hg(I) halides

Relativistic density functional calculations were performed on Hg 2L 2 units in the Madelung potential of the solid halides (L  F, Cl, Br, I) and also of Hg 2L 2 embedded in a halide surrounding. Consistent structural parameters and a consistent set of explanations of the details of structure and bonding are obtained. Our results are at variance with older powder and single crystal X-ray diffraction results on the different Hg 2L 2 compounds. The calculated HgHg bond length is nearly independent of the ligands. It contracts by 5 pm or more upon solidification of the Hg 2L 2 molecules. Experimental redetermination of some crystallographic parameters is recommended.

Preparation and M�ssbauer study of iron-mercury halide complexes containing isocyanide and carbonyl ligands

Complexes [Fe(t-BuNC)n(CO)5-n](n = 1 or 2) react with equimolar amounts of mercury(II) halides in acetone to form neutral iron-mercury adducts [Fe(t-BuNC) (CO)4−(HgX2)] and [Fe(t-BuNC)2(CO)3(HgX2)] (X = Cl or I), while [Fe(t-BuNC)5] reacts with solid mercury halides in petroleum ether to give the salts [Fe(t-BuNC)5(HgX)]-HgX3 (X = Br or I). Product assessment was based upon analytical and spectroscopic data, the Mossbauer effect and on molar conductivity studies.

Thermochemistry of inorganic solids. 10. Empirical relations between the enthalpies of formation of solid halides and the corresponding gas-phase halide anions

Equation 4, Δ(MX n )=aΔ(M'X n )+b, where M and M' are two different metals, both with formal valence n, Δ(MX n ) is defined by eq 3, Δ(MX n )=Δ f H o (MX n , cr)-Δ f H o (X - , g), and for a selected pair of metals, M and M', X can be any of the halogens, has been found to correlate the standard enthalpies of formation, Δ f H o , at 298 K for any solid halides with the corresponding gas-phase halide ions

Mechanism of the oxygen sensing electrode on solid halide electrolytes

The solid state galvanic cells: P o2 , M/PbF 2/M, P ref (M=RuO 2, Pt or iron phthalocyanine: FePc) have been studied in the temperature range 150–370°C. At temperatures higher that 300°C, the EMF dependence on the oxygen pressure is in good agreement with the expected Nernst Law. At lower temperature, a change of mechanism is demonstrated. A theoretical analysis is presented.

Moessbauer studies of graphite intercalation compounds of antimony chloridefluorides

Graphite reacts with antimony pentahalides to form intercalation compounds with metallic conductivity. There has been a lot of discussions about the chemical species inhabiting the galleries in SbF 5- and SbCl 5-graphite. Recent investigations suggest that SbX − 6 and SbX 3 are formed as result of an electron transfer from graphite to the intercalate layers. 121Sb Mössbauer spectrometry is used for determination the valence state and molecular configuration of Sb in SbCl 4F- and SbCl 2F 3-graphite. Besides SbCl 5-graphite which was synthesized by a soft intercalation technique in CCl 4-solution has been investigated. The spectra exhibit one strong line which is assigned to Sb 5+ (>95%). The isomer shift δ IS relative to CaSnO 3 increases by replacing Cl by F in the compounds: C xSbCl 5 (−2.75 mms −1), C xSbCl 4F (−1.43), C xSbCl 2F 3 (+0.12), C xSbF 5 (+2.06). Relatively high values of quadrupole splitting indicate low symmetry in the intercalated species. The intercalation compounds show higher isomer shift than the solid halides. This difference may be due to a partial electron transfer and formation of polymeric anions containing halogen bridges. The amount of Sb 3+ in the graphite lattice could be increased by annealing a mixture of halides and graphite at 150°C for one week. It is to be assumed that intercalated antimony trihalides originate from thermal decomposition.

Theory of Phase Transitions in Molecular Crystals Applied to the Solid Hydrogen Halides

Phase transitions in the hydrogen halide crystal which is composed of an array of linear molecules with nearest neighbor coupling are theoretically investigated by making use of the Frenkel model. The Hamiltonian is a sum of dipolar and quadrupolar interactions. The method of symmetry-breaking potential is applied with the use of an inverse temperature expansion. The results obtained are compared with those of the theory by Krieger and James, who investigated the orientational transitions with no attention to a particular substance by making use of the Pauling model. Depending upon the ratio of the coupling constants, we have a single second order transition, a single first order transition, two successive first order transitions, or a first order transition followed by a second order transition as the temperature lowers. A triple point is found, at which two different types of ordered phases and a disordered phase coexist.

Preparation and investigation of properties of divalent americium ions in aqueous solutions by the impulse radiolysis method

Divalent americium has been identified only as solid halides [i]. There are no data on the existence of Am(II) in aqueous solutions. We have obtained a demonstration of formation of Am(II) ions during irradiation of aqueous solutions of Am(III) perchlorate by the impulse radiolysis method with ra~id spectrophotometric registration of the short-lived species. It was found that a short-lived optical absorption with a maximum at 310 nm forms as a result of reaction of electron pulses on a deaerated 3.10 -3 M solution of Am(CIO~)3 (pH 4.7-6~ containing 0.i mole/liter of tert-butanol (an OH radical acceptor). The intensityofabsorption is significantly lower in the case of a solution with pH ~ 3. It was also observed that the rate of disappearance of hydrated electrons (eaq-~ in the presence of Am(III) ions is significantly higher than in their absence. This-value correlates with the rate of formation of the absorption. From this it follows that the examined absorption is due to the reaction product of Am(III~ with eaa, i.e., Am(II~ ions. The rate constant of their formation is equal to 3.108 liter/mole.sec (pH ~ 6). These ions are unstable in aqueous solutions. For example, their disappearance occurs with a period of half conversion of 70 ~sec at pH 4.7-4.8.

A Note on the Induction Period of Photographic Development

AbstractHistorical and conceptual aspects of the induction period of photographic development are reviewed. The term, first introduced into photography by Sheppard and Mees, is now used in reference both to individual grains and to whole emulsions, leading to some confusion. According to the mode of presenting data, an induction period can appear or disappear. Given the electrode model of development, the bold S-shape of the density-time curve for hydroquinone can follow simply from the dependence of rate on the effective surface area of clumps of silver filaments. It is, rather, the absence of this type of induction period that calls for special comment to establish how the body of solid silver halide can play a rate-determining role.

Nuclear spin-lattice relaxation in solid cuprous halides

Measurements have been made by pulsed NMR of the spin-lattice relaxation times T1 of 63Cu, 65Cu and 81Br nuclei in three polycrystalline cuprous halides of zinc blende structure from 78 to 300 K. The temperature dependence of T1 is well described by Van Kranendonk's temperature function and testifies to a two-phonon quadrupolar relaxation mechanism. The ratio of values of T1 for 63Cu and 65Cu is in all cases in good agreement with the inverse square of their quadrupole moments. The fivefold increase in T1 for copper nuclei on proceeding from CuCl through CuBr to CuI is attributed predominantly to its dependence on the thirteenth power of the lattice parameter. Values of gamma , the parameter characterizing antishielding and other effects, of order 103 are required to account for absolute values of T1.

Solid Halides and other Ionic Conductors

Solid Halides and other Ionic Conductors