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Calcium ion batteries are provided. The calcium ion batteries include a cathode, an alloying anode composed of one or more intermetallic calcium compounds in electrical communication with the cathode; and an electrolyte disposed between the anode and the cathode. The intermetallic calcium compounds are intermetallic compounds of calcium and transition metals and metalloids.
The Lunar Sulfur Capture System (LSCS) protects in situ resource utilization (ISRU) hardware from corrosion, and reduces contaminant levels in water condensed for electrolysis. The LSCS uses a lunar soil sorbent to trap over 98 percent of sulfur gases and about two-thirds of halide gases evolved during hydrogen reduction of lunar soils. LSCS soil sorbent is based on lunar minerals containing iron and calcium compounds that trap sulfur and halide gas contaminants in a fixed-bed reactor held at temperatures between 250 and 400 C, allowing moisture produced during reduction to pass through in vapor phase. Small amounts of Earth-based polishing sorbents consisting of zinc oxide and sodium aluminate are used to reduce contaminant concentrations to one ppm or less. The preferred LSCS configuration employs lunar soil beneficiation to boost concentrations of reactive sorbent minerals. Lunar soils contain sulfur in concentrations of about 0.1 percent, and halogen compounds including chlorine and fluorine in concentrations of about 0.01 percent. These contaminants are released as gases such as H2S, COS, CS2,HCl, and HF during thermal ISRU processing with hydrogen or other reducing gases. Removal of contaminant gases is required during ISRU processing to prevent hardware corrosion, electrolyzer damage, and catalyst poisoning. The use of Earth-supplied, single-use consumables to entirely remove contaminants at the levels existing in lunar soils would make many ISRU processes unattractive due to the large mass of consumables relative to the mass of oxygen produced. The LSCS concept of using a primary sorbent prepared from lunar soil was identified as a method by which the majority of contaminants could be removed from process gas streams, thereby substantially reducing the required mass of Earth-supplied consumables. The LSCS takes advantage of minerals containing iron and calcium compounds that are present in lunar soil to trap sulfur and halide gases in a fixedbed reactor downstream of an in-ISRU process such as hydrogen reduction. The lunar-soil-sorbent trap is held at a temperature significantly lower than the operating temperature of the hydrogen reduction or other ISRU process in order to maximize capture of contaminants, but is held at a high enough temperature to allow moisture to pass through without condensing. The lunar soil benefits from physical beneficiation to remove ultrafine particles (to reduce pressure drop through a fixed bed reactor) and to upgrade concentrations of iron and/or calcium compounds (to improve reactivity with gaseous contaminants).
Chemical scandium isotope separation from calcium compounds containing radioactive calcium 48
Calcium-ion batteries (CIBs) are a promising next-generation energy storage system given the low redox potential of calcium metal and high abundance of calcium compounds. For continued CIB development, the discovery of high energy density calcium ion cathodes is needed to achieve practical energy density values. Here, we report on the use of elemental Se as a promising candidate for a high-capacity cathode material for CIBs that operates via a conversion mechanism in a Ca metal battery at room temperature. The Se electrodes demonstrate a reversible specific capacity of 180 mA h g –1 with a discharge plateau near 2.0 V (vs Ca 2+ /Ca) at 100 mA g –1 using an electrolyte based on the salt calcium tetrakis(hexafluoroisopropyloxy)borate (Ca(B(hfip) 4 ) 2 ) in 1,2-dimethoxyethane (DME) and Ca metal. The reversible electrochemical reaction between calcium and selenium is investigated using operando synchrotron-based techniques and the possible reaction mechanism discussed.
Methods are described for impregnating coal with calcium carbonate by utilizing an aqueous phase ionic reaction between calcium acetate, calcium hydroxide, and water with CO.sub.2 contained within the coal. The coal is enriched in CO.sub.2 by contacting it with CO.sub.2 at high pressure, in either a continuous or pulsed mode. The inclusion of CO.sub.2 in the coal during the process does not involve evacuating the coal and subsequently absorbing CO.sub.2 onto the coal as in prior methods. Rather, the coal is treated with carbon dioxide at high pressure in a practical and viable approach. The impregnation of coal by calcium compounds not only reduces sulfur emissions by effectively tying up the sulfur as calcium sulfide or sulfate, but also increases the gasification or combustion rate. The invention also encompasses the use of other Group IIA elements, as well as the coal products resulting from the methods of treatment described.
Efforts to prepare Ca(O2) sub 2 from reactions of calcium compounds with 100% O3 and with O(D-1) atoms generated by photolysis of O3 at 2537 A are described. Samples of Ca(OH) sub 2, CaO, CaO2, Ca metal, and mixtures containing suspected impurities to promote reaction have been treated with excess O3 under static and flow conditions in the presence and absence of UV irradiation. Studies with KO2 suggest that the superoxide anion is stable to radiation at 2537 A but reacts with oxygen atoms generated by the photolysis of O3 to form KO3. Calcium superoxide is expected to behave in an analogous.
Calcium-ion batteries (CIBs) are a promising alternative to lithium-ion batteries (LIBs) due to the low redox potential of calcium metal and high abundance of calcium compounds. Due to its layered structure, α-MoO 3 is regarded as a promising cathode host lattice. While studies have reported that α-MoO 3 can reversibly intercalate Ca ions, limited electrochemical activity has been noted, and its reaction mechanism remains unclear. Here, we re-examine Ca insertion into α-MoO 3 nanoparticles with a goal to improve reaction kinetics and clarify the storage mechanism. The α-MoO 3 electrodes demonstrated a specific capacity of 165 mA h g –1 centered near 2.7 V vs Ca 2+ /Ca, stable long-term cycling, and good rate performance at room temperature. Furthermore, this work demonstrates that, under the correct conditions, layered oxides can be a promising host material for CIBs and renews prospects for CIBs.
Polycrystalline Bi{sub 2}Sr{sub 2}Ag{sub 0.03}Ca{sub 1}Cu{sub 2}O{sub y} samples were fabricated using conventional solid-state reaction method. Then, post-annealing temperatures at 730, 780 and 830 {sup ∘}C were applied on samples while time was kept constant at 50 h. Both the x-ray diffraction (XRD) measurement and the scanning electron microscopy (SEM) showed that all samples have high amounts of Bi-2212 phase as the main phase, indicating that the selected starting composition is suitable to analyze the post-annealing effects on the flux pinning properties of Bi-2212 superconductors. In particular, flux pinning performance of Bi-2212 phase is observed from both the magnetic hysteresis loops and J{sub c} values calculated using Bean’s model. The highest J{sub c} value was obtained for sample which was not exposed to the post-annealing treatment. The results clearly show that post-annealing procedure in Bi{sub 2}Sr{sub 2}Ag{sub 0.03}Ca{sub 1}Cu{sub 2}O{sub y} system does not create artificial pinning centres, which lead to the improvements in J{sub c} at high magnetic fields.
The paper reports on the temperature dependencies of the electrical resistivity and the a.c. magnetic susceptibility of the Tl{sub 0.8}Bi{sub 0.3}Sr{sub 1.8}Ba{sub 0.2}Ca{sub 2}Cu{sub 3}O{sub x} bulk superconductor measured in the area of the transition from the metallic to the superconducting state. From the resistivity data, the onset temperature T{sub c,onset}= 121.6 K, the critical temperature T{sub c50%}= 118.8 K, the zero resistance critical temperature obtained using E= 10{sup − 6} V/cm criterion T{sub c0}= 117.9 K, and the width of superconducting transition ΔT= 1.6 K were derived. The thermal fluctuations were examined using the formulae for the conductance: Δσ=Kε{sup −λ}, and for the magnetic susceptibility: χ = Cε{sup −λ}, where Δσ=1/R(T)−1/R{sub R}(T), ε= | (T − T{sub c})/T{sub c}|, λ is the critical exponent, and K and C are constants. The critical exponents in the transition region from the normal to the superconducting state were determined and analyzed. The three-dimensional fluctuations were found to occur in the vicinity of the zero-resistance critical temperature.
Flux pinning characteristics of Cu{sub 0.5}Tl{sub 0.5}Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 12−δ} samples synthesized by two-step solid-state reaction method have been studied by physical properties measurement system (PPMS). These thin films are oriented along c-axis and have shown the tetragonal crystal structure. In the resistivity measurements, these samples have shown T{sub c} (R = 0) around 106 K. Asymmetric M vs. H loop of the samples at various temperature shows the interaction bulk and surface pinning. The energy of activation derived from the slope of Log(J{sub c}) vs. reduced temperature enhances with the increase strength of applied field. The irreversibility field suppress with the increase in the measurement temperature. The pinning energy per unit length of flux votex ε and the de-pinning force also suppress with increase of measurement temperature. The H{sub c1}, H{sub c}, and H{sub c2} (hence the H{sub irr}) are suppress with the increase of measurement temperature, since the H{sub c} determines the free energy difference between the normal and superconducting state. The increase in the H{sub c} at lower temperature shows that the density of superconducting electrons increases with the suppression of temperatures. The enhancement in the density of superconducting carriers at low temperatures would increase the coherence length and suppress the population of flux vortices. It can be seen in the form of decreased values of Ginzburg Landau parameter κ and the penetration depth λ{sub D}.
The juxtaposition of superconductivity and magnetism is an interesting research topic due to the exclusivity nature of both phenomena. In this paper, we report the effect of nanosized (~ 5 nm) nickel zinc ferrite Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} (NZFO) on Bi{sub 1.6}Pb{sub 0.4}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Bi-2223) superconductor. Bi-2223 powders were prepared using the co-precipitation method. Samples with starting formula Bi{sub 1.6}Pb{sub 0.4}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}(Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}){sub x} for x = 0 to 0.1 wt% have been prepared. The structure, microstructure, electrical resistance, and AC susceptibility were determined. The transport critical current density, J{sub ct}, was measured using the 1 μV/cm criterion. The non-added sample sintered for 48 h showed the highest zero resistance temperature, T{sub c-zero} (105 K) and J{sub ct} of 1.83 A cm{sup −2} at 40 K. The x = 0.02 wt% sample sintered for 48 h (T{sub c-zero} = 103 K) showed the highest J{sub ct} of 5.30 A cm{sup −2} at 40 K. The peak temperature of the imaginary part of the complex susceptibility, T{sub p}, increased with sintering time and nanoparticle addition, indicating full flux penetration occurred at higher temperatures and improved intergrain coupling. NZFO nanoparticle did not suppress the transition temperature but it improved the transport critical current density by more than five times indicating it enhanced flux pinning and connectivity between grains in the Bi-2223 phase.
Among the various theoretical mechanisms proposed to reach a higher Tc, the interface mechanism in different forms has been the one most explored, and it provides continual inspiration and hope for realizing the ultimate goal for researchers in the superconductivity field—room-temperature superconductivity. Difficulties do exist, as most of the materials proposed to exhibit the interfacial mechanism are artificially formed heterostructures and are by nature delicate and easily disturbed by strain and change in the stoichiometry at the interface. The discoveries of superconductivity in naturally assembled single crystals of rare earth (R)-doped CaFe2As2 (Ca122) with a Tc up to 49 K and undoped CaFe2As2 with a Tc up to 25 K have opened an alternate route to tackle the problem. The experimental observation has provided the most direct evidence for interface-induced superconductivity in Ca122 to date and possibly in R-doped Ca122. Given the fact that neither chemical doping nor the application of physical pressure has ever induced a Tc higher than 40 K in bulk FeSe, the reports of Tc up to 45–109 K in FeSe/STO thin films demonstrate that FeSe/STO is an ideal system in which to explore interface-enhanced superconductivity. Here we review the above three specific examples of our effort toward superconductors of higher Tc to demonstrate that the interface mechanism may be a promising paradigm to achieve higher Tc.
In this work, the effect of cesium substitution on the structural and superconducting properties of Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Cs{sub x}Cu{sub 2}O{sub +y} (where x = 0.0, 0.025, 0.050, 0.075, 0.10, 0.125, and 0.15) samples prepared by the solid-state reaction route and by directional growth using the laser floating zone (LFZ) technique has been studied. X-ray diffraction has shown that both kinds of samples present the 2212 phase as the major one, with pseudo tetragonal structure, accompanied by minor amounts of (Sr,Ca)CuO{sub 2} and Bi{sub 2}(Sr,Ca){sub 4}O{sub 6 + d} secondary phases. SEM-EDX results indicate that Bi-2212 phase is the major one, with small amounts of secondary phases. Cs substitution diminishes the size and content of secondary phases. Magnetization measurements reflect different behavior for sintered and LFZ grown samples. Although the diamagnetic transition is very wide for the former samples, it is very sharp for the last ones. The critical onset temperatures, T{sub C}, are around 80 and 90 K, for sintered and LFZ grown samples, respectively. Moreover, M–H measurements indicate that LFZ grown samples exhibit larger areas than the sintered ones. The intragranular critical current, J{sub C}, calculated from the M–H loops and Bean’s formula, is maximum for x = 0.025Cs sintered and x = 0.05Cs LFZ grown samples. The maximum pinning forces, F{sub Pmax}, determined in these samples are higher than those obtained in undoped ones, reaching 9 × 10{sup 7} Oe*A/cm{sup 2} and 10 × 10{sup 8} Oe*A/cm{sup 2}, at 10 K, for sintered and LFZ grown samples, respectively.
The electron-pairing mechanism in unconventional high-temperature superconductors (HTS) has not been resolved. We proposed that the electron-pairing medium of unconventional HTS is the change of the electron clouds of transition metal ions, which is analogous to the lattice vibration in conventional superconductors. Real-time evolution of the electron clouds of transition metal ions under excitations in La{sub 2}Fe{sub 2}As{sub 2}O{sub 2}, FeSe sheet, and HgBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub 8} was calculated by the time-dependent density functional theory (TDDFT). The characteristic frequencies are 160 meV, 190 meV, and 250 meV, respectively. The frequencies are close to that of the lattice vibration in conventional HTS at high pressures, showing that the change of the electron clouds of the transition metal ions can be the electron-pairing medium.
It was investigated that the influence of Ca substitution by Zn on the specific resistivity, thermal power, and excess conductivity of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub X}, Bi{sub 2}Sr{sub 2}Ca{sub 0.8}Zn{sub 0.2}Cu{sub 2}O{sub X}, and Bi{sub 2}Sr{sub 2}Ca{sub 0.4}Zn{sub 0.6}Cu{sub 2}O{sub X} polycrystalline samples in the 70–300 K temperature interval. The fluctuation-induced conductivity is analyzed using the Aslamasov and Larkin and Lawrence and Doniach models. The microscopic parameters such as dimensional crossover temperature (T{sub cr}), interlayer coupling strength (J), and zero temperature coherence length along c axis (ξ{sub 0}) are estimated.
This work presents a novel approach based on the nitrate decomposition method for the preparation the oxygen-deficient LaBaCaCu{sub 3}O{sub y} (La1113) compound. The XRD results reveal the presence of the triple perovskite structure LaBaCaCu{sub 3}O{sub y} as a dominant phase crystallizing in the tetragonal system with the space group P4/mmm. The SEM observation shows a low porosity and EDAX data indicates the presence of the basic elements of the phase. The superconducting character of the compound is confirmed by AC susceptibility measurements with T{sub c} = 63 K even if the samples are not treated under oxygen atmosphere.
A Y-type hexagonal ferrite with chemical composition CaBaCo{sub 2}In{sub 0.5}Fe{sub 11.5}O{sub 22} was prepared by a sol-gel auto combustion technique. Y-ferrite/PANI nanocomposites were prepared by in situ polymerization of PANI with general formula CaBaCo{sub 2}In{sub 0.5}Fe{sub 11.5}O{sub 22} (1-x) + PANI (x) (x = 0.30, 0.50, 0.8, and 1) with nomenclature CF1, CF2, CF3, and P respectively. The samples were characterized by X-ray diffraction (XRD) and electrical and magnetic measurements. X-ray diffraction revealed that Y-type ferrite was successfully prepared in a single phase form. DC resistivity increases with increasing ferrite filler in nanocomposites due to large resistive behavior of ferrite in conducting polymer matrix. The dielectric constant, dielectric loss, and AC conductivity decreases with the increase of ferrite content. The dielectric is high due to interfacial polarization at low frequency, and it is low at high frequency following Maxwell-Wagner model. The coercivity increases with the decrease of ferrite filler content whereas saturation magnetization and remanence decreases which is due to random distribution of ferrite filler particles in PANI matrix. Due to large coercivity and low values of ε′ and ε″, the present samples may be useful in recording media and electromagnetic shielding.
The transmission electron backscatter diffraction (t-EBSD) technique has proven to be an indispensable tool for the analysis of microstructures of superconducting samples, both high-T{sub c} samples (YBa{sub 2}Cu{sub 3}O{sub y}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}) as well as MgB{sub 2} or iron-based materials. The knowledge of the grain boundary properties (misorientation, length, width) is essential for the further optimization of sample performance. Any addition of secondary phase(s) to improve the flux pinning properties is required to be of nanometer dimensions, so the higher achievable resolution and the better imaging properties are important to obtain reasonably high image quality to enable automated orientation mapping. The orientation maps reveal not only the location and the shape of the inclusions within the superconducting matrix or at the grain boundaries but also their influence on the surrounding superconducting matrix, which also plays an important role in flux pinning. In the case of sintered MgB{sub 2} bulk samples, the demand for higher critical current densities leads to MgB{sub 2} grains in the 100-nm range, which is already difficult to be studied by means of conventional EBSD. Furthermore, t-EBSD is useful for the analysis of specific microstructures of unconventional superconductors like superconducting foams or superconducting nanowire networks.