LiF-LiVO3-Li2SO4-Li2MoO4 four-component system

The LiF-LiVO₃-Li₂SO₄-Li₂MoO₄ four-component system was studied using differential thermal analysis. The eutectic composition was determined (mol %): LiF, 25.0; LiVO₃, 43.8; Li₂SO₄, 14.8; Li₂MoO₄, 16.5. The eutectic melting point is 428°C; the enthalpy of melting is 260 J/g.     

LiF-LiBr-LiVO3-Li2MoO4-Li2SO4 quinary system

Phase equilibria in the LiF-LiBr-LiVO₃-Li₂MoO₄-Li₂SO₄ quinary system were studied by differential thermal analysis. A eutectic composition was determined to be 4.0 mol % LiF, 38.4 mol % LiBr, 30.8 mol % LiVO₃, 19.2 mol % Li₂MoO₄, and 7.6 mol % Li₂SO₄ with a melting point of 372°C and an enthalpy of melting of 164 ± 7 kJ/kg.     

The LiF-LiCl-Li2SO4-Li2MoO4 quaternary system

Phase equilibria in the LiF-LiCl-Li₂SO₄-Li₂MoO₄ quaternary system have been investigated by differential thermal analysis. The eutectic composition (in mol %) has been determined as LiF, 16.2; LiCl, 51.5; Li₂SO₄, 16.2; and Li₂MoO₄, 16.2. The melting point of the eutectic is 402°C, and the enthalpy of melting is 291 J/g.     

Binary systems with Li2SO4 as one of the components

Six binary systems were studied using DTA with supplementary XRD. In Li₂SO₄?MSO₄ systems (M=Mg, Co, Ni), a primary solid solution with α-Li₂SO₄ structure (high-temperature form) and an incongruent melting compound Li₂M_y(SO₄)_1+y exist:y=2 with Mg andy=1 with Co and Ni. In Li₂SO₄?Li₃XO₄ systems (X=P, V), which are very different from one another, only primary solid solutions exist. In the Li₂SO₄?Li₂B₄O₇ system there is neither a solid solution nor an intermediate compound. Comparisons with previous investigations are made.     

Synthesis and evaluation as CO_2 chemisorbent of the Li_5(Al_(1-x)Fe_x)O_4 solid solution materials: Effect of oxygen addition

Pentalithium aluminate(β-Li_5AlO_4) and the corresponding iron-containing solid solution(Li_5(Al_(1-x)Fe_x)O_4)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, N_2 adsorption-desorption and temperature-programmed desorption of CO_2. Results showed that 30 mol% of iron can be incorporated into the β-Li_5AlO_4 crystalline structure at aluminum positions. Moreover, iron addition induced morphological and superficial reactivity variations. Li_5(Al_(1-x)Fe_x)O_4 samples chemisorbed CO_2 between 200 and 700 °C, where the superficial chemisorption presented the highest enhancement,in comparison to β-Li_5AlO _4. Additionally, Li_5(Al_(1-x)Fe_x)O_4 samples sintered at higher temperatures thanβ-Li_5AlO_4. Isothermal CO_2 chemisorption experiments of β-Li_5AlO_4 and Li_5(Al_(1-x)Fe_x)O_4 were fitted to a first order reaction model, corroborating that iron enhances the CO_2 chemisorption, kinetically. When oxygen was added to the gas flow, CO_2 chemisorption process was mainly enhanced between 400 and 600 °C for the Li_5(Al_(0.8)Fe_(0.2))O_4 sample in comparison to β-Li_5AlO_4. Hence, Li_5(Al_(1-x)Fe_x)O_4 solid solution presented an enhanced CO_2 chemisorption process, in the presence and absence of oxygen, in comparison to β-Li_5AlO_4.     

The effects of Li2SO4 addition,moisture, and LiOH on the ionic conductivity of Li5AIO4

The ionic conductivity and thermal properties of 80Li₅AlO₄ + 20Li₂SO₄, 75Li₂SO₄ + 25LiOH, and 50Li₂SO₄ + 50LiOH composite polycrystalline samples have been determined in both wet and dry environments. A large increase in the ionic conductivity of 80Li₅AlO₄ + 20Li₂SO₄ in a wet environment above ～350°C is due to the presence of LiOH. This same increase in conductivity is found for the two LiOH + Li₂SO₄ mixtures and is related to a eutectic reaction in the Li₂SO₄LiOH system. The phase diagram for the Li₂SO₄LiOH system was determined and supports this conclusion. The conductivity of 80Li₅AlO₄ + 20Li₂SO₄ in a dry environment is thermally activated [$\text{σ = σ}{}_0\text{exp}\text{(}\text{?E}\text{kT}\text{)}$] with E = 0.66 eV and $\text{σ}{}_0\text{= 450 (Ω-}\text{cm}\text{)}{}^{\mathrm{?1}}$. The addition of Li₂SO₄ to Li₅AlO₄ increases the total conductivity but decreases the electronic conductivity. Pressed pellets of Li₅AlO₄ and 80Li₅AlO₄ + 20Li₂SO₄ are stable in lithium up to at least 550 and 450°C, respectively.     

LiF-LiCl-LiVO<Subscript>3</Subscript>-Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>-Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript> system

Phase equilibria in the LiF-LiCl-LiVO₃-Li₂SO₄-Li₂MoO₄ system have been studied by differential thermal analysis. The eutectic composition has been determined as follows (mol %): LiF, 17.4; LiCl, 42.0; LiVO₃, 17.4; Li₂SO₄, 11.6; and Li₂MoO₄, 11.6, with the melting temperature equal to 363°C and the enthalpy of melting equal to (284 ± 7) kJ/kg.     

Zur Kenntnis von Ag6(SO4)(SiO4)

About Ag₆(SO₄)(SiO₄) Hitherto unknown Ag₆(SO₄)(SiO₄) has been prepared at 400–500°C under an oxygen pressure more than 1000 atm. By single crystal X-ray work the structure of tetragonal Ag₆(SO₄)(SiO₄) has been elucidated: a = 7.060, c = 17.660 Å; D?14₁/amd; Z = 4. The crystal structure shows a new type in which the tetrahedrally sulfat- and silicat groups are definite distinguishable. As well the both crystallographic silver positions show a different crystal-chemical character.     

Water activity,osmotic and activity coefficients of aqueous solutions of Li2SO4, Na2SO4, K2SO4, (NH4)2SO4, MgSO4, MnSO4, NiSO4, CuSO4, and ZnSO4 at T=298.15 K

The water activities for aqueous solutions of Li₂SO₄(aq), Na₂SO₄(aq), K₂SO₄(aq), (NH₄)₂SO₄(aq), and sulphates MgSO₄(aq), MnSO₄(aq), NiSO₄(aq), CuSO₄(aq), and ZnSO₄(aq) were determined experimentally at a temperature of 298.15 K with a hygrometric method, at molalities in the range from 0.1 mol·kg⁻¹ to saturation. The osmotic coefficients are calculated from these results. The coefficients of Pitzer’s model was used to fit the osmotic coefficients for each salt solution. These parameters were used to predict solute activity coefficients for the salts studied.     

Einbau von Na2SO4 in die Hochtemperaturform des Na3PO4

Formation of Solid Solutions of Na₂SO₄ in the High-temperature Form of Na₃PO₄ The high-temperature form of Na₃PO₄ solves up to 70 mole-% Na₂SO₄ maintaining the type of crystal structure. The lattice constants increase from 742.3(1) pm (pure Na₃PO₄) to 749.1(2) pm for Na^3?x(PO₄)^?x(SO₄)_x (x = 0.7). The high-temperature form, in the case of pure Na₃PO₄ stable above 325°C, is stabilized at room-temperature by doping with small amounts of Na₂SO₄.     

LiF-LiBr-LiVO3-Li2SO4 four-component system

Phase equilibria in theLiF-LiBr-LiVO₃-Li₂SO₄ four-component system were studied using dif ferential thermal analysis (DTA). The eutectic composition (mol %) was determined as LiF, 20.0; LiBr, 45.7; LiVO₃, 25.7; Li₂SO₄, 8.6 with a melting temperature of 403°C and a specific enthalpy of melting of 216 kJ/kg.     

Ein neues Lithiumhydrogensulfat,Li2(HSO4)2(H2SO4) – Synthese und Kristallstruktur

A New Lithium Hydrogen Sulfate, Li₂(HSO₄)₂(H₂SO₄) – Synthesis and Crystal Structure The title compound crystallizes in good shaped single crystals from the system lithium sulfate/sulfuric acid in the orthorhombic space group Pccn, unit cell parameters a = 17.645(4), b = 5.378(1), c = 10.667(3) Å. V = 1 012.2 ų, Z = 4, D_x = 2.009 g cm^?3. There are two types of SO₄ tetrahedra, SO₃(OH) and SO₂(OH)₂, connected via hydrogen bonds forming layers parallel to the xy-plane. The layers are linked by Li atoms, which are tetrahedral coordinated by O atoms coming two by two from neighboured layers.     

Neue Silicate mit „Stuffed Pyrgoms”︁: CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 [1] und RbNaLi4{Li[SiO4]}2 [2]

More Silicates with ?Stuffed Pyrgoms”?: CsKNaLi₉{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄, RbNa₃Li₈{Li[SiO₄]}₄ [1] and RbNaLi₄{Li[SiO₄]}₂ [2] Single crystals of the new silicates CsKNaLi₉{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄, RbNa₃Li₈{Li[SiO₄]}₄ and RbNaLi₄{Li[SiO₄]}₂ as well as powder (Rb-containing compounds only) were obtained for the first time. The samples were prepared by heating well ground mixtures of the binary oxides in Ni and Ag tubes, respectively. The structure determination was carried out by four-circle diffractometer data (MoKα radiation; Siemens AED 2): CsKNaLi₉{Li[SiO₄]}₄: tetragonally prismatic crystals, light yellow; 726 I₀(hkl), R = 4.4%, R_w = 2.8%; a = 1 102.0(6), c = 637.9(5) pm; Z = 2; space group I4/m; 2 CsO_0.55 + Li₄TlO₄ + glas (560°C, 15 d). CsKNa₂Li₈{Li[SiO₄]}₄: tetragonally prismatic crystals, light yellow; 727 I₀(hkl), R = 4.4%, R_w = 2.6%; a = 1 103.5(7), c = 637.7(4) pm; Z = 2; space group I4/m; 1.1 CsO_0.61 + 1.1 KO_0.55 + 1.4 NaO_0.52 + 6.5 Li₂O + 4 SiO₂ (600°C, 60 d). RbNa₃Li₈{Li[SiO₄]}₄: tetragonally prismatic crystals, colourless; 600 I₀(hkl), R = 2.3%, R_w = 2.0%; a = 1 092.08(6), c = 632.76(4) pm; Z = 2; space group I4/m; 4 RbO_0.57 + 3 NaO_0.52 + 6.5 Li₂O + 4 SiO₂ (650°C, 63 d). RbNaLi₄{Li[SiO₄]}₂: monoclinic, ball-shaped, colourless; 1 224 I₀(hkl), R = 3.1%, R_w = 3.1%; a = 1 573.10(13), b = 630.48(5), c = 781.25(8) pm, b = 90.566(8)°; Z = 4; space group C2/m; 1.1 RbO_0.52 + 1.2 NaO_0.45 + 5 Li₂O + 4 SiO₂ (700°C, 40 d).     

Struktur und thermisches Verhalten von Gadolinium(III)-sulfat-Octahydrat Gd2(SO4)3 · 8 H2O

Structure and Thermal Behaviour of Gadolinium(III)-sulfate-octahydrate Gd₂(SO₄)₃ · 8 H₂O . Gd₂(SO₄)₃ · 8 H₂O crystallizes monoclinic with space group C2/c and the lattice constants a = 13.531(7), b = 6.739(2), c = 18.294(7) Å, β = 102.20(8)°. In the structure Gd is coordinated by 4 oxygen atoms of crystal water and 4 oxygens of sulfate giving rise to a distorted square antiprism. During DTA-TG-experiments the title compound first loses crystal water in a two-step mechanism in the temperature range 130–306°C. The resulting Gd₂(SO₄)₃ is amorphous and recrystallization occurs in the range 380–411°C. The so-obtained low-temperature modification β-Gd₂(SO₄)₃, undergoes a monotropic phase transition at about 750°C to the high-temperature form α-Gd₂(SO₄)₃. The powder pattern of this modification was indexed based on monoclinic symmetry with space group C2/c and lattice constants a = 9.097(3), b = 14.345(5), c = 6.234(2) Å, β = 97.75(8)°. The hightemperature modification of gadolinium-sulfate shows decomposition to Gd₂O₂SO₄ at 900°C and, subsequently, decomposition at 1 200°C yields the formation of C-Gd₂O₃.     

Phase equilibria in systems of gallium sulfate with lithium or sodium sulfate

The phase diagrams of binary systems of gallium sulfate with lithium or sodium sulfate were studied for the first time. The Li₂SO₄–Ga₂(SO₄)₃ system is of the eutectic type. The coordinates of the eutectic are (548°C, 30 mol % Ga₂(SO₄)₃). The region of a solid solution based on the high-temperature modification α-Li₂SO₄ is small. In the Na₂SO₄–Ga₂(SO₄)₃ system, compound Na₃Ga(SO₄)₃ forms, which melts incongruently at 585°C. The coordinates of the eutectic are (538°C, 17 mol % Ga₂(SO₄)₃). The region of a solid solution based on α-Na₂SO₄ reaches 8 ± 1 mol % Ga₂(SO₄)₃. The X-ray powder diffraction pattern of Na₃Ga(SO₄)₃ was indexed in a tetragonal unit cell with the parameters a = 9.451(3) Å and c = 7.097(3) Å; the unit cell parameters for an aluminum-containing analog, Na₃Al(SO₄)₃, are a = 9.424(5) Å and c = 7.053(3) Å.     

Effects of Cr doping on the electrochemical performance of Li3V2(PO4)3 cathode material for lithium ion batteries

A series of Cr-doped Li₃V_2 − x Cr _x (PO₄)₃ (x = 0, 0.1, 0.25, and 0.5) samples are prepared by a sol–gel method. The effects of Cr doping on the physical and chemical characteristics of Li₃V₂(PO₄)₃ are investigated. Compared with the XRD pattern of the undoped sample, the XRD patterns of the Cr-doped samples have no extra reflections, which indicates that Cr enters the structure of Li₃V₂(PO₄)₃. As indicated by the charge–discharge measurements, the Cr-doped Li₃V_2 − x Cr _x (PO₄)₃ (x = 0.1, 0.25, and 0.5) samples exhibit lower initial capacities than the undoped sample at the 0.2 C rate. However, both the discharge capacity and cycling performance at high rates (e.g., 1 and 2 C) are enhanced with proper amount of Cr doping (x = 0.1). The highest discharge capacity and capacity retention at the rates of 1 and 2 C are obtained for Li₃V_1.9Cr_0.1(PO₄)₃. The improvement of the electrochemical performance can be attributed to the higher crystal stability and smaller particle size induced by Cr doping.

     

Three-component systems LiBr-LiVO<Subscript>3</Subscript>-Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript> and LiBr-Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>-Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>

Phase equilibria in the three-component systems LiBr-LiVO₃-Li₂MoO₄ and LiBr-Li₂SO₄-Li₂MoO₄ have been studied using differential thermal analysis (DTA). Eutectic compositions have been determined (mol %): in the system LiBr-LiVO₃-Li₂MoO₄, 56.0 LiBr, 22.0 LiVO₃, and 22.0 Li₂MoO₄ with a melting temperature of 413°C; and in the system LiBr-Li₂SO₄-Li₂MoO₄, 65.0 LiBr, 14.0 Li₂SO₄, and 21.0 Li₂MoO₄ with a melting temperature of 421°C. Phase fields have been demarcated.     

Investigation of the LiF-LiBr-Li2SO4-Li2MoO4 quaternary system

Phase equilibria in the LiF-LiBr-Li₂SO₄-Li₂MoO₄ system have been investigated by differential thermal analysis. The eutectic composition has been determined (mol %): LiF, 13.3; LiBr, 62.0; Li₂SO₄, 15.4; and Li₂MoO₄, 9.3. The melting point is 415°C, and the ehthalpy of melting is 200 kJ/kg. Original Russian Text ? T.V. Gubanova, E.I. Frolov, E.G. Danilushkina, I.K. Garkushin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 6, pp. 1037–1042.     

Pt2(HSO4)2(SO4)2, the First Binary Sulfate of Platinum

Red single crystals of Pt₂(HSO₄)₂(SO₄)₂ were obtained by the reaction of elemental platinum with conc. sulfuric acid at 350 °C in sealed glass ampoules. The crystal structure (monoclinic, P2₁/c, Z = 2, a = 868.6(2), b = 826.2(1), c = 921.8(2) pm, β=116.32(1)°, R_all = 0.0348) shows dumbbell shaped Pt₂⁶⁺ cations which are coordinated by four SO₄^2— and two HSO₄^— ions. Each of the sulfate ions is attached to another Pt₂⁶⁺ ion yielding layers according to equation/tex2gif-stack-1.gif[Pt₂(SO₄)_4/2(HSO₄)_2/1]. The layers are connected by hydrogen bonds with the OH group of the hydrogensulfate ion as donor and the non‐bonding oxygen atom of the sulfate ion as acceptor.     

Thermodynamic properties of aqueous mixtures of LiCl and Li2SO4 at different temperatures

Emf measurements were made on the cell without liquid junction: Li?ISE LiCl(m₁), Li₂SO₄(m₂) Ag/AgCl. The performances of the electrode pairs constructed in our laboratory were tested and exhibited near-Nernstian behavior. The mean activity coefficients of LiCl for the system Li⁺?Cl^??SO ₄ ^2? ?H₂O have been investigated by the emf values at temperatures of 0, 15, 35°C and constant total ionic strengths of 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 5.0 mol·kg^?1. The activity coefficients decrease with increasing temperature and the ionic strength fraction of Li₂SO₄ in the mixtures. The thermodynamic properties are interpreted by use of Harned's empirical equations and Pitzer's ion interaction approach including the contribution of higher order electrostatic terms. The experimental results obey Harned's rule and are described by using Pitzer equations satisfactorily. The activity coefficients of Li₂SO₄, the osmotic coefficients and the excess free energies of mixing for the system in the experimental temperature range were reported.