Synthesis of complex sulfide phases on the CaYb<Subscript>2</Subscript>S<Subscript>4</Subscript>-Y<Subscript>2</Subscript>S<Subscript>3</Subscript> quasibinary section and investigation of their structural and electrolytic properties

The possibility of synthesizing sulfide-conducting solid electrolytes in the CaYb₂S₄-Y₂S₃ quasibinary system is tested for the first time. The system is characterized by the X-ray diffraction analysis and the electron microscopy. The total conductivity of specimens is found by the conductometric method. The ionic and electronic transport numbers are determined based on the modified versions of the emf method and the Hebb-Wagner polarization method. The possible mechanism of defect formation is discussed.     

Synthesis, structure, and physico-chemical properties of sulfide ceramics CaY2S4-Yb2S3

Solid solutions are synthesized in the system of CaY₂S₄-Yb₂S₃. Temperature and concentration dependences of electrolytic properties are studied, the sulfide ion-based conductivity is confirmed. It is shown that the high contribution of ion conductivity in the synthesized phases is due to formation of charged vacancies. Mechanisms of defect formation are suggested.     

The thermodynamic characteristics of formation of ternary sulfides MeLn2S4 and solid solutions based on them

The thermodynamic characteristics of formation of ternary sulfides CaGd₂S₄ and BaTm₂S₄ from Ca(Ba)S and Gd₂(Tm₂)S₃ binary sulfides were determined using various modifications of the electromotive force method. Activity and cationic and anionic transfer numbers in extended phases based on MeLn₂S₄ were studied simultaneously. CaGd₂S₄ and BaTm₂S₄ were found to be stable over the electrolytic temperature range 653–723 K. The stability boundaries of phases based on CaY₂S₄. BaTm₂S₄, CaPr₂S₄, and CaSm₂S₄ were determined. A vacancy mechanism of defect formation with predominantly sulfide ion transfer was suggested for sequential doping of ternary with binary sulfides.     

Investigation on the effect of nanosilica towards corn starch–lithium perchlorate-based polymer electrolytes

Biodegradable corn starch–lithium perchlorate (LiClO₄)-based solid polymer electrolytes with addition of nano-sized fumed silica (SiO₂) were prepared by solution casting technique. Ionic conductivity at ambient temperature was measured by AC impedance spectroscopy. Upon addition of nano-sized SiO₂, the ionic conductivity at room temperature is increased. The optimum ionic conductivity value obtained was 1.23?×?10^?4?S?cm^?1 at 4?wt% SiO₂. This may be attributed to the low crystallinity of the polymer electrolytes resulting from the dispersed nanosilica particles. Fourier–transform infrared spectroscopy studies confirmed the complexation between corn starch, lithium perchlorate, and silica. The thermal properties of the prepared samples were investigated with differential scanning calorimetry and thermogravimetric analysis. The surface morphology of the polymer electrolytes confirmed the agglomeration of particles after excess dispersion of inorganic filler. This was proven in the scanning electron microscopy studies.     

Synthesis,Characterization, Thermal Analyses,and Spectroscopic Properties of Novel Naphthyl-Functionalized Imidazolium Ionic Liquids

A series of novel ionic liquids based on naphthyl-functionalized imidazolium cation have been prepared. Their structure was characterized by NMR. The thermal stabilities of the prepared liquids were studied by thermal gravimetric analysis. The new ionic liquids containing NTf^-₂ anion display significantly higher thermal stabilities (>400°C). Anion exchange to PF^-₆, BF^-₄, and Br^– decreases the thermal stabilities of such ionic liquids. Fluorescence and UV–Vis absorption spectroscopy were used to study the spectroscopic properties of the ionic liquids. Compared with common ionic liquids, the described ionic liquids provide robust fluorescence properties and remarkably increased UV–Vis absorption. This research may enrich the field of functionalized ionic liquids and provide a platform for extension of ionic liquid applications.     

Synthesis and Electrolytic Properties of Phases Based on Calcium Thiogadolinate as a Function of Method of the Precursor Synthesis

Differently treated phases based on CaGd₂S₄ are studied by electrochemical methods. The range of solid solutions, electrolytic temperature interval, and averaged transport numbers for ions and electrons are determined. Compositions with best electrolytic properties are established. The origin of conduction in a CaGd₂S₄-based solid electrolyte is investigated. The obtained data show the phases to be sulfide-conducting solid electrolytes with a small share of cationic conduction.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 633–639.Original Russian Text Copyright © 2005 by Medvedeva, Kalinina, Metlin, Ushakova.     

Synthesis and crystal structures of CaY2Ge3O10 and CaY2Ge4O12

New compounds CaY₂Ge₃O₁₀ and CaY₂Ge₄O₁₂ were prepared by heating mixtures of CaCO₃, Y₂O₃ and GeO₂ at 1200 °C. CaY₂Ge₃O₁₀ is stable at 1300 °C, while CaY₂Ge₄O₁₂ decomposes into a melt and CaY₂Ge₃O₁₀ at approximately 1250 °C. We obtained single crystals of CaY₂Ge₃O₁₀ by cooling a sample with an initial composition of Ca:Y:Ge=1:2:8 from 1300 °C with a rate of −6 °C/h. The crystal structure of CaY₂Ge₃O₁₀ was determined by single crystal X-ray diffraction. CaY₂Ge₃O₁₀ crystallizes in the monoclinic space group P2₁/c with a=6.0906(8), b=6.8329(8), and β=109.140(3)°, Z=4, and R₁=0.029 for I>2σ(I). In the structure of CaY₂Ge₃O₁₀, Ca and Y atoms are situated disorderly in three 7-fold coordination sites between isolated germanate groups of triple GeO₄ tetrahedra, Ge₃O₁₀. The structural formula of CaY₂Ge₃O₁₀ is expressed as (Ca_0.45Y_0.55)(Ca_0.46Y_0.54)(Ca_0.09Y_0.91)Ge₃O₁₀. The crystal structure of CaY₂Ge₄O₁₂ was analyzed by the Rietveld method for the X-ray powder diffraction pattern. CaY₂Ge₄O₁₂ is isotypic with SrNa₂P₄O₁₂, crystallizing in the orthorhombic space group P4/nbm, a=9.99282(6), , Z=2, R_wp=0.092, R_p=0.067. CaY₂Ge₄O₁₂ contains four-membered GeO₄-tetrahedra rings, Ge₄O₁₂. Eight-fold coordinated square-anitiprism sites and 6-fold octahedral sites between the layers of the Ge₄O₁₂ rings are occupied by Y atom and Ca/Y atoms, respectively The structural formula is Y(Ca_0.5Y_0.5)₂Ge₄O₁₂.     

Synthesis and Physicochemical Properties of a Lanthanum-Containing Analog of the Mineral Berthierite FeSb<Subscript>2</Subscript>S<Subscript>4</Subscript>

Phase equilibria in the FeSb₂S₄–FeLa₂S₄ system were studied by physicochemical analysis methods (differential thermal, X-ray powder diffraction, and microstructural analyses and microhardness and density measurements), and the phase diagram of the system was constructed. The formation of quaternary sulfide FeLaSbS₄ melting congruently at 1230 K, an analog of the mineral berthierite FeSb₂S₄, was detected. The X-ray powder diffraction analysis showed that FeLaSbS₄ belongs to the berthierite structural type and crystallizes in the orthorhombic system with the unit cell parameters a = 11.424 Å, b = 14.160 Å, c = 3.782 Å, Z = 4, and space group Pbam.     

Electrolytic properties and stability of solid solutions of ytterbium sulfide in calcium thioytterbate

Solid solutions of Yb₂S₃ based on CaYb₂S₄ (Yb₃S₄) were prepared by the ceramic and sol-gel methods. The samples were identified by XRD. The electric conductivity of complex sulfide phases with different backgrounds was studied. The length of phases based on CaYb₂S₄ was determined. The thermal stability of the samples was tested and the range of working temperatures was determined.     

Thermal oxidation of concentrates of Co-Ni thiospinels

Co-Ni concentrates whose major phase components are pentlandite (Ni,Fe,Me)₉S₈, linneite Co₃S₄, polydymite Ni₃S₄, and siegenite NiCo₂S₄ were subjected to oxidation with atmospheric oxygen under the conditions of nonisothermal and isothermal heating in the interval 20–900°C. The process was studied by differential thermal, X-ray phase, and chemical analysis. The reaction schemes based on the data obtained were suggested, and the optimal temperature interval of low-temperature sulfatizing roasting of Co-Ni thiosphinels was chosen.     

Transport properties of metacomposites in eutectic MAO<Subscript>4</Subscript>–V<Subscript>2</Subscript>O<Subscript>5</Subscript> systems (M = Ca,Sr; A = W,Mo)

Metal molybdates MMoO₄ (M = Ca, Sr) and their composites with vanadium oxide V₂O₅ were synthesized. An X-ray diffraction analysis confirmed that the obtained molybdates were single-phase, and the heterogeneous systems were two-phase. The temperature dependences of the total conductivity of the composites were studied. The ion transport numbers in the {CaMoO₄ · xV₂O₅} composites (x = 1–30 mol %) were studied by the EMF method. The conductivity of the composites at x ≤ 5 mol % was shown to be ionic. The conductivity of the composites was described using the mixing equation.     

Low-viscosity and low-melting point asymmetric trialkylsulfonium based ionic liquids as potential electrolytes

Nine new ionic liquids based on small asymmetric trialkylsulfonium cations with TFSI⁻ anion were prepared and characterized. Physical and electrochemical properties of these ionic liquids, including melting point, thermal stability, viscosity, conductivity and electrochemical window were determined. Reducing symmetry of cations reduces the melting points of these ILs. Some of these hydrophobic ionic liquids showed low-viscosity and low-melting point characteristics. The viscosities of S₂₂₃TFSI, S₂₂₁TFSI and S₁₂₃TFSI were 33, 36 and 39 mPa s at 25 °C, respectively. Electrochemical and thermal stabilities of these ILs permitted them to become promising electrolytes used in electrochemical devices.     

Synthesis of BaSnO<Subscript>3</Subscript>/SnO<Subscript>2</Subscript> Nanocomposites as Heterogeneous Additive for Composite Solid Electrolytes

Method of differential thermal analysis was used to study the thermolysis of a mixture of barium oxalate hydrate and α-SnO₂·H₂O, produced by precipitation from hydrochloric solutions. The methods of X-ray diffraction analysis, electron microscopy, and low-temperature nitrogen adsorption were used to examine the reaction products formed at various heating temperatures and determine their phase composition. The nanocomposite BaSnO₃/SnO₂ is the final product of thermolysis and subsequent heating to 950°C. The nanocomposite was used as a heterogeneous oxide additive for obtaining a CsNO₂–BaSnO₃/SnO₂ composite solid electrolyte. The conductivity of the composite exceeds that of the starting salt by more than order of magnitude.     

Intermediate temperature ionic conductivity of Sm1.92Ca0.08Ti2O7–δ pyrochlore

The results of concentration cell electromotive force methods (EMF) and electrochemical impedance spectroscopy measurements on the pyrochlore system Sm_1.92Ca_0.08Ti₂O_7–δ are presented. The data have been used to estimate total and partial conductivities and determine transport numbers for protons and oxide ions under various conditions. The EMF techniques employed include corrections for electrode polarisation resistance. The measurements were performed using wet and dry atmospheres in a wide \( {p_{{{{\rm{O}}_{{2}}}}}} \) range using mixtures of H₂, N₂, O₂, and H₂O in the temperature region where proton conductivity was expected (500–300 °C). The impedance measurements revealed the conductivity to be mainly ionic under all conditions, with the highest total conductivity measured being 0.045 S/m under wet oxygen at 500 °C. Both bulk and grain boundary conductivity was predominantly ionic, but electronic conductivity appeared to play a slightly larger part in the grain boundaries. EMF data confirmed the conductivity to be mainly ionic, with oxide ions being the major conducting species at 500 °C and protons becoming increasingly important below this temperature.

     

Studies on poly(vinyl pyrrolidone) based solid polymer blend electrolytes complexed with various lithium salts

Solid polymer electrolytes (SPEs) with high ionic conductivity and acceptable mechanical properties are of particular interest for increasing the performance of batteries. In the present work, SPEs based on poly(ethylene oxide)/poly (vinyl pyrrolidone) (PEO/PVP) with various lithium salts were prepared by solvent casting technique. The amorphous nature of the polymer-salt complex was studied by X-ray diffraction analysis. The complexation of the prepared electrolytes was confirmed by Fourier transform infrared analysis. Ionic conductivity as a function of frequency was studied at various temperatures in the range of 303–353 K. The maximum ionic conductivity value was found to be 1.08 × 10^?5 S/cm for the film containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) at room temperature and the temperature dependent ionic conductivity values seem to obey Vogel-Tamman-Fulcher relation. Thermogravimetry was used to ascertain the thermal stability of the electrolytes. Photoluminescence measurements demonstrated that the sample having maximum ionic conductivity shows the minimum luminescence intensity. Ultra violet-visible analysis reveals that the values of the band gap energies were changed with the addition of various lithium salts. Porosity of the sample containing lithium bis trifluoromethane sulfonoimide (LiN[CF₃SO₂]₂) was studied by Atomic force microscope.     

Thermoelectric Properties of Nano-grained Mooihoekite Cu9Fe9S16

Cu-Fe-S-based compounds gain the interest from thermoelectric community because all the consisting elements, Cu, Fe, and S, are non-toxic and earth-abundant. Comparing with CuFeS₂ and Cu₅FeS₄, the investigation on Cu₉Fe₉S₁₆ is very rare. In this work, a series of Cu_9–xFe_9+xS₁₆ samples were fabricated by means of melting-annealing process. Their phase composition, microstructure, electrical and thermal transport properties were systematically investigated. X-ray measurement confirms that all samples are phase pure. Transmission electron microscopy characterization indicates that the fabricated Cu₉Fe₉S₁₆ has a natural nanostructure. Cu₉Fe₉S₁₆ shows semiconducting-like electrical transport behavior and intrinsically low lattice thermal conductivity. Beyond the numerous boundaries between nanosized grains, the existence of low-frequency optical phonons is also responsible for the intrinsically low lattice thermal conductivity. Doping Fe at the Cu-sites in Cu₉Fe₉S₁₆ significantly alters the electrical transport properties by introducing extra carriers. A peak dimensionless figure of merit zT value of 0.21 is obtained at 800 K for pure Cu₉Fe₉S₁₆, which is comparable with that for CuFeS₂.     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.     

Synthesis,crystal structure and optical properties of A3Zr2P5S18 (A=Rb,Cs): the first quaternary zirconium thiophosphates

The first quaternary zirconium thiophosphates Rb₃Zr₂P₅S₁₈ (1) and Cs₃Zr₂P₅S₁₈ (2) were synthesized by reacting ZrS₂ with an in situ formed melt of A₂S₃ (A=Rb, Cs), P₂S₅ and S. The compounds are isostructural and crystallize in the monoclinic space group Cc with Z=4. Compound 1 has cell parameters a=9.248(2) Å, b=9.860(2) Å, c=33.622(7) Å and β=94.73(3)° and compound 2 a=9.288(2) Å, b=9.956(2) Å, c=34.061(7) Å and β=94.26(3)°. The structures are composed of a two-dimensional anionic layer [Zr₂P₅S₁₈]³⁻ and intervening alkali cations. Each of the two independent Zr atoms is surrounded by seven S atoms yielding a distorted pentagonal bipyramid. The ZrS₇ polyhedra are interconnected into the final layered anion by [P₂S₇] groups which act in an unusual edge- and corner-sharing mode and by edge-sharing [PS₄] tetrahedra. Compound 2 was characterized with MIR and UV/vis diffuse reflectance spectroscopy.     

Synthesis of 2-amino-1,3-dihydroxypropylphosphonates from Garner aldehyde

In the presence of triethylamine or ionic fluoride catalysts, the addition of dimethyl or diethylphosphite to Garner aldehyde proceeded with good (1:9) diastereoselectivity leading to a separable mixture of (1S,2S)- and (1R,2S)-hydroxyphosphonates. Almost equal amounts (43:57) of the respective phosphonates were formed when titanium(IV) isopropoxide was applied as a catalyst. The e.e.s of the hydroxyphosphonates reached 93–97% in the reactions catalysed by Ti(OiPr)₄ and dropped to 80–91% when triethylamine was used to catalyse the reaction.     

Cooperative Proton and Li-ion Conduction in a 2D-Layered MOF via Mechanical Insertion of Lithium Halides

Ionic conduction in highly designable and porous metal–organic frameworks has been explored through the introduction of various ionic species (H⁺, OH⁻, Li⁺, etc.) using post-synthetic modification such as acid, salt, or ionic liquid incorporation. Here, we report on high ionic conductivity (σ>10⁻² S cm⁻¹) in a two-dimensionally (2D)-layered Ti-dobdc (Ti₂(Hdobdc)₂(H₂dobdc), H₄dobdc: 2,5-dihydroxyterephthalic acid) via LiX (X=Cl, Br, I) intercalation using mechanical mixing. The anionic species in lithium halide strongly affect the ionic conductivity and durability of conductivity. Solid-state pulsed-field gradient nuclear magnetic resonance (PFG NMR ) verified the high mobility of H⁺ and Li⁺ ions in the temperature range of 300–400 K. In particular, the insertion of Li salts improved the H⁺ mobility above 373 K owing to strong binding with H₂O. Furthermore, the continuous increase in Li⁺ mobility with temperature contributed to the retention of the overall high ionic conductivity at high temperatures.