N-shaped nonlinearity of charge characteristics of ionistor structures based on RbAg <Subscript>4</Subscript>I<Subscript>5</Subscript>

The charging of ionistors—capacitors with an electrical double layer based on RbAg₄I₅—reveals an N-shaped nonlinearity of charge characteristics. The nature of the effect is discussed and its microscopic interpretation is proposed.     

Thermodynamic study of Cu-Tl-Te system using EMF technique with Cu<Subscript>4</Subscript>RbCl<Subscript>3</Subscript>I<Subscript>2</Subscript> solid electrolyte

The EMF method with a solid Cu⁺-conducting electrolyte of Cu₄RbCl₃I₂ was sued to study the Cu-Tl-Te system in the temperature range of 300–420 K. A diagram of solid-phase equilibriums of this system is constructed, partial molar functions of copper in alloys, standard thermodynamic functions of formation and standard entropies of CuTlTe₂, CuTl₄Te₃, Cu₂TlTe₂, Cu₃TlTe₂, Cu₉TlTe₅ triple compounds and Cu _x Tl_{5 − x} Te₃ solid solutions (0 < x < 1) are calculated. The obtained results confirmed the assumption as to the possibility of using this modification for the EMF technique for thermodynamic studies of copper-containing triple systems, even if they contain a less noble component than copper.     

Cu<Subscript>4</Subscript>RbCl<Subscript>3</Subscript>I<Subscript>2</Subscript> solid superionic conductor in thermodynamic study of three-component copper chalcogenides

The Cu-B-Se (B = In, As, Sb, Bi) systems are studied by measurement of EMF for concentration circuits vs. a copper electrode in the temperature range of 300–430 K. A solid superionic Cu₄RbCl₃I₂ conductor is used as an electrolyte. Diagrams of solid-phase equilibriums in the studied systems are constructed. Partial molar functions of alloyed copper are calculated on the basis of the equations of the temperature dependences of EMF. Potential-forming reactions corresponding to the measured EMF values are determined on the basis of the phase diagrams and standard thermodynamic formation functions and standard entropies of ternary compounds are calculated.     

Thermodynamic study of Ag<Subscript>8</Subscript>GeSe<Subscript>6</Subscript> by EMF with an Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> solid electrolyte

The Ag–Ge–Se system was studied in the range of compositions Ag₂Se–GeSe₂–Se by measuring the EMF of the concentration (relative to the silver electrode) circuits with a solid electrolyte Ag₄RbI₅ in the temperature range 290–430 K. The polymorphic transition temperature of Ag₈GeSe₆ (320 K) was determined and the partial molar functions of silver were calculated for both crystal modifications of this compound based on the EMF measurements. The thermodynamic functions of formation and entropy of both modifications of Ag₈GeSe₆ and the thermodynamic functions of its polymorphic transition were calculated.     

Thermodynamic study of glasses in Ag-As-Se system using EMF method with Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> solid electrolyte

The EMF method with Ag₄RbI₅ solid electrolyte was used to study silver solubility in Ag-As-Se glasses on the basis of the cross-sections of (I) Ag-As_0.25Se_0.75, (II) Ag-As_0.33Se_0.67, (III) Ag-As_0.4Se_0.6, and (IV) Ag-As_0.5Se_0.5. It is found that silver solubility reaches 30 and 40 at % in sections (I), (IV) and (II), (III), accordingly. The data of EMF measurements were used as a basis for calculation of partial polar functions of Ag in glasses. The Gibbs-Duhem equations were integrated to calculate thermodynamic functions of silver dissolution in vitreous As _x Se_{1 − x} (x = 0.25; 0.33; 0.4; 0.5), from which the corresponding data for the latter were used to obtain the standard integral thermodynamic functions of the mixing of glasses. The obtained results were compared with the thermodynamic data for crystalline silver selenoarsenites.     

Hydrogen storage in borohydrides Comparison of hydrolysis conditions of LiBH<Subscript>4</Subscript>, NaBH<Subscript>4</Subscript> and KBH<Subscript>4</Subscript>

The hydrogen storage capabilities of alkaline borohydrides through a hydrolyzing process were determined by taking into consideration the hydration of the end products. Comparison of LiBH₄, NaBH₄ and KBH₄ showed their storage capacities to be dependent on the composition of the metaborate formed. This composition is ruled by the hydrolysis conditions, especially the temperature reached during the reaction and the stability of the hydrates. The borohydride with the highest hydrogen content in the solid state, LiBH₄, could be less efficient than KBH₄ if the hydrolysis is performed at 120°C.     

Electrochemical properties of solid electrolytes based on BaSm<Subscript>2</Subscript>S<Subscript>4</Subscript>

Solid solutions based on BaSm₂S_{4 ? x} mol % BaS (Sm₂S₃) are obtained. Oxide intermediates were homogenized using chemical and mechanical mixing methods. The solid solution region is determined. Complex conductivity is studied and conductivity activation energy is calculated for samples with different history. Electrolytic properties of phases based on barium thiosamarate are studied. Vacancy mechanism of defect formation is suggested.     

Synthesis and crystal structure of new double mercury silver phosphide iodide Hg<Subscript>12</Subscript>Ag<Subscript>41</Subscript>P<Subscript>88</Subscript>I<Subscript>41</Subscript>

New double mercury silver phosphide iodide Hg₁₂Ag₄₁P₈₈I₄₁ (1) was synthesized and its crystal structure was established. Compound 1 crystallizes in the cubic system. The characteristic feature of the crystal structure 1 is the presence of the anionic cage clusters P₁₁ ³⁻, which have been previously found in alkali metal compounds only. The well-ordered P₁₁ ³⁻ clusters form a system of polyhedra, which encapsulate various disordered α-AgI-type fragments. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1882–1886, October, 2007.     

Polymorphism and thermal decomposition of [Ni(DMSO)<Subscript>4</Subscript>]I<Subscript>2</Subscript>

Tetrakis(dimethyl sulphoxide)nickel(II) bis(iodide) was studied by thermogravimetry (TG) and simultaneous differential thermal analysis (SDTA) and differential scanning calorimetry (DSC). The gaseous products of the decomposition were on-line identified by a quadrupole mass spectrometer (QMS). Thermal decomposition of the title compound proceeds in three main stages. In the first stage, which starts just above ca. 419 K, the compound loses two dimethyl sulphoxide (DMSO) molecules per one formula unit and small amount of iodide ion. In the second stage (464–552 K) the next DMSO ligands and the iodide ion simultaneously are released. In the last stage (552–900 K) NiSO4 is created which next decomposes to NiO and SO₃.     

Endohedral Complex of Fullerene C<Subscript>60</Subscript> with Tetrahedral N<Subscript>4</Subscript>, N<Subscript>4</Subscript>@C<Subscript>60</Subscript>

B3LYP/6-31G(d) hybrid HF/DFT and BLYP/6-31G(d, p) DFT calculations were carried out to determine the structural and electronic properties of the endohedral complex of C₆₀ with Tetrahedral N₄ (T_d N₄), N₄@C₆₀. It was demonstrated that N₄ was seated in the center of the fullerene cage and the tetrahedral structure of N₄ is remained in the cage. The formation of this complex is endothermic with inclusion energy of 37.92 kcal/mol. N₄ endohedral doping perturbs the molecular orbitals of C₆₀ not so much, the calculated HOMO–LUMO gaps, the electron affinity (EA) and the ionizational potential (IP) of N₄@C₆₀ are similar to that of C₆₀.     

Thermodynamic study of the Ag-As-Se and Ag-S-I systems using the EMF method with a solid Ag<Subscript>4</Subscript>RbI<Subscript>5</Subscript> electrolyte

The EMF method with a solid Ag₄RbI₅ superionic conductor was used to study the Ag-As-Se and Ag-S-I systems in the composition ranges of Ag₂Se-As₂Se₃-Se and Ag₂S-AgI-S, accordingly. Their solid-phase equilibrium diagrams are constructed or specified. The existence of ternary AgAs₃Se₅, AgAsSe₂, Ag₃AsSe₃, Ag₇AsSe₆, Ag₃SI compounds is confirmed. The standard partial and integral thermodynamic formation functions and also standard entropies were calculated for these compounds for the first time.     

Effect of starting materials on electrochemical performance of sol-gel-synthesized Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> anode materials for lithium-ion batteries

In this study, the effect of the sol-gel starting materials with different particle sizes on the sol-gel-synthesized spinel Li₄Ti₅O₁₂ (LTO) was systematically investigated. The physical and electrochemical properties of the synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller-specific surface area analyses, galvanostatic charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. It was found that the initial particle size of sol-gel starting material played a crucial role on the properties of as-prepared LTOs. The LTO synthesized with the relatively finer particle size of starting materials possessed relatively smaller particle size and larger specific surface area and therefore resulted in the superior electrochemical properties. The initial discharge capacity of the as-prepared LTO exhibited 168.2, 150.6, and 142.7 mAh g^?1 at current densities of 1, 5, and 10 C, respectively, and up to 95, 95, and 90 % of the corresponding initial discharge capacity was retained after 50 cycles.     

Electochemical characteristics of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>/Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> battery with conducting polymeric binder

Lithium-ion battery based on LiMn₂O₄/Li₄Ti₅O₁₂ materials was assembled for the first time. The cathode and anode of this battery are prepared with the aqueous combined binder poly-3,4-ethylenedioxythiophene: polystyrene sulfonate/carboxymethylcellulose (without polyvinylidene fluoride). The capacity of the LiMn₂O₄/Li₄Ti₅O₁₂ battery was found to be 75 mA h g^–1 at 0.1 C and 55 mA h g^–1 at 1 C. A 95% capacity was retained after 100 charge-discharge cycles. The batteries demonstrated a high Coulombic efficiency close to 100%. Scanning electron microscopy demonstrated that using the conducting binder poly-3,4-ethylenedioxythiophene: polystyrene sulfonate/carboxymethylcellulose provides formation of dense compact layers of electrode materials with good adhesion to the substrate. The electrode structure remains maintained after 100 charge-discharge cycles.     

Study of Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> interaction with solid lithium-containing electrolytes

Compatibility of the lithium-titanium spinel Li₄Ti₅O₁₂ in contact with precursors of lithium-conducting solid electrolytes of composition Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP), Li_0.5La_0.5TiO₃ (LLT) was studied. It was found that, in sintering of Li₄Ti₅O₁₂ brought in contact with LATP and LAGP, a solid-phase reaction occurs to give nonconducting phases (TiO₂ and Li₃PO₄). The conductivity of the stable composite Li₄Ti₅O₁₂/LLT (10%) is higher than that of the starting Li₄Ti₅O₁₂, which makes it possible to regard the composite as a promising anode material for lithium-ion batteries.     

Bismuth in quaternary and quinary solid solutions based on A<Subscript>3</Subscript>B<Subscript>5</Subscript> compounds

The heterophase equilibria in the InBiAsSb and GaInBiAsSb systems are analyzed in the context of simple solutions. Linear interpolation is to determine the thermodynamic and crystal-chemical parameters for virtual GaBi compound. The boundaries of existence for InBiAsSb and GaInBiAsSb solid solutions are calculated and the thermodynamic limits that characterize their synthesis are determined for the temperature range of 650–780 K. Heteroepitaxial InBiAsSb/InSb structures are formed on the basis of our analysis by zone recrystallization according to temperature gradient (ZRTG).     

Interaction of solid electrolyte La<Subscript>0.88</Subscript>Sr<Subscript>0.12</Subscript>Ga<Subscript>0.82</Subscript>Mg<Subscript>0.18</Subscript>O<Subscript>2.85</Subscript> with hydrogen,water vapor,and carbon dioxide

The air,Au/La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85/Au,air cells are studied by an impedancemetry method before and after a week-long exposure at 700°C to atmospheres of hydrogen, humid air, and carbon dioxide. Blank specimens of the same electrolyte are examined by methods of x-ray diffraction, Raman scattering (RS), and x-ray photoelectron spectroscopy. The fact that the shape of the RS spectra and the shape of the electrode impedance dispersion alter unequivocally suggests that, at the very least, the electrode surface interacts with all the gases. The interaction in question is reversible in the case of hydrogen and carbon dioxide. In the case of water vapor, the interaction is irreversible.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 198–205.Original Russian Text Copyright © 2005 by Shkerin, Kovyazina, Beresnev, Kalashnikova, Martemyanova.This revised version was published online in April 2005 with corrections to the article note and article title and cover date.     

The synthesis and properties of solid solutions based on Ba<Subscript>4</Subscript>Ca<Subscript>2</Subscript>Nb<Subscript>2</Subscript>O<Subscript>11</Subscript>

(Ba_{1 ? x} Ca _x )₆Nb₂O₁₁ solid solutions were synthesized. The compositions were shown to be single-phase at 0.23 ≤ x ≤ 0.47 and have a double perovskite cubic structure with an incomplete oxygen sublattice. The interaction of solid solutions with water vapor and their electrical properties were studied. In dry atmosphere, these complex oxides were mixed oxygen-hole conductors. In humid atmosphere, they intercalated water and exhibited protonic conductivity. The influence of Ba/Ca isovalent substitution, the dynamics of the oxygen sublattice, and the concentration of intercalated water on the value and contribution of protonic and hole conductivity was analyzed.     

Whitlockite solid solutions in the Ca<Subscript>3</Subscript>(VO<Subscript>4</Subscript>)<Subscript>2</Subscript>-K<Subscript>3</Subscript>VO<Subscript>4</Subscript>-NdVO<Subscript>4</Subscript> system

Phase equilibria in the Ca₃(VO₄)₂-K₃VO₄-NdVO₄ system have been studied. An extensive calcium orthovanadate-based solid solution was found to form with the boundary compositions as follows: Ca₃(VO₄)₂-Ca₉Nd(VO₄)₇-Ca_9.33K_2.33(VO₄)₇-Ca_7.88K_2.63Nd_0.87(VO₄)₇. The unit cell parameters of the whit-lockite vanadates synthesized increase as the potassium and neodymium contents increase. Phase transitions from the low-temperature β phase to the β′ centrosymmetrical structure in Ca_{9.33 − 5z} K_{2.33 + z} Nd_3z (VO₄)₇ vanadates have been studied dilatometrically. The increase in the β ai β′ transition temperature caused by potassium is interpreted as arising from the filling in of vacant cation positions M(4) and M(6).     

The reactivity of SbVO<Subscript>5</Subscript> with T-Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> in solid state in air

The reactivity of SbVO₅, a compound known since a short time, with T-Nb₂O₅ in solid state in air has been investigated over the whole component concentration range of a system built by these two reacting substances. The investigation results have shown that an equimolar mixture of SbVO₅ and T-Nb₂O₅ reacts with a subsequent formation of a hitherto unknown compound of the formula Nb₂VSbO₁₀. This compound has been characterized by the methods XRD, DTA/TG, and SEM. Its orthorhombic unit cell parameters have been calculated, and its stability in air up to 880 ± 10 °C has been proved. At this temperature, the compound melts incongruently with an accompanying deposition of solid Nb₉VO₂₅, i.e., of a compound that crystallizes in the binary oxide system V₂O₅–Nb₂O₅.     

Synthesis and properties of nanocrystalline materials based on LaPO<Subscript>4</Subscript>

A study of the processes in which lanthanum orthophosphate nanocrystalline powders with rhabdophane and monazite structure and crystallite size of about 10 nm are formed demonstrated that, at temperatures of up to 500°C, nanocrystalline lanthanum orthophosphate with rhabdophane structure loses crystal hydrate water and is transformed at 520–540°C to a nanocrystalline phase with monazite structure. This transition is not associated with as change in the crystallite size because nanocrystals of the anhydrous lanthanum orthophosphate phase with monazite structure retain a size of about 10 nm both at the instant of the structural transformation and up to temperatures of 600–700°C. The technological modes were determined in which nanocrystalline lanthanum orthophosphate powders with monazite structure can be obtained and the powders are used for sintering of ceramic materials with porosity on the level of 5–7%.