Li+/H+ ion exchange in Li3 ? 2xNbxM2 ? x(PO4)3 (M = In, Fe) materials with a NASICON structure

H_{3 − 2x} Nb _x M_{2 − x} (PO₄)₃ (M = In, Fe) acid phosphates have been obtained by ion exchange from their lithium forms and X-ray powder diffraction, impedance measurements, and ⁷Li and ¹H NMR spectroscopy. The parameters of the hexagonal unit cell of the proton-exchanged forms differ only slightly from those of the initial lithium compounds. According to ¹H NMR data, the proton in the acid phosphates is not hydrated. The conductivity of the acid phosphates at high temperatures depends weakly on their composition and is ∼1.7 × 10⁻⁷ S cm⁻¹ at 620 K. The activation energy of conduction is 30–33 kJ/mol (430–770 K).     

Cation mobility in modified Li1 + xTi2 ? xGax(PO4)3 lithium titanium NASICON phosphates

Li_{1 +x} Ti_{2 − x} Ga _x (PO₄)₃(x= 0−0.2) NASICON double phosphates are prepared and studied by high-temperature X-ray diffraction, ⁷Li NMR spectroscopy, impedance spectroscopy, and calorimetry. Doping with Ga³⁺ cations increases cation mobility in LiTi₂(PO₄)₃. Ion conductivity, NMR spectroscopy, and calorimetry data imply the occurrence of a phase transition in LiTi₂(PO₄)₃ and in products of partial gallium-for-titanium substitution. Original Russian Text ? I.Yu. Pinus, I.V. Arkhangel’skii, N.A. Zhuravlev, A.B. Yaroslavtsev, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1235–1239.     

Cation mobility in modified Li1 ? xTi2 ? xNbx(PO4)3 lithium titanium NASICON phosphates

Li_{1 − x} Ti_{2 − x} Nb _x (PO₄)₃ NASICON materials are prepared and studied by X-ray diffraction, ⁷Li and ³¹P NMR spectroscopy, and impedance spectroscopy. Vacancy mobility in Li_{1 − x} Ti_{2 − x} Nb _x (PO₄)₃ is lower than interstitial lithium mobility. Nb⁵⁺ cations with low doping levels increase cation mobility in LiTi₂(PO₄)₃. Original Russian Text ? I.Yu. Pinus, I.A. Stenina, A.I. Rebrov, N.A. Zhuravlev, A.B. Yaroslavtsev, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1240–1244.     

Synthesis and thermal characterization of NZP compounds Na1?xLixZr2(PO4)3 (x?=?0.00–0.75)

Sodium zirconium phosphate (NZP) composition Na_1−x Li _x Zr₂(PO₄)₃, x = 0.00–0.75 has been synthesized by method of solid state reaction method from Na₂CO₃·H₂O, Li₂CO₃, ZrO₂, and NH₄H₂PO₄, sintering at 1050–1250 °C for 8 h only in other to determine the effect on thermal properties, such as the phase formation of the compound. The materials have been characterized by TGA and DTA thermal analysis methods from room temperature to 1000 °C. It was observed that the increase in lithium content of the samples increased thermal stability of the samples and the DTA peaks shifted towards higher temperatures with increase in lithium content. The thermal stability regions for all the sample was observed to be from 640 °C. The sample with the highest lithium content, x = 0.75, exhibited the greatest thermal stability over the temperature range.     

Dehydrogenation of butyl alcohols on NASICON-type solid electrolytes of Na1 ? 2xCuxZr2(PO4)3 composition

Characteristics of the catalytic activity in the dehydration of butanols of copper-containing sodium-zirconium-phosphates (NZPs), in which Na⁺ ions substitute for Cu²⁺ ions are obtained. It was found that in the 100–370°C region, the action energy of the reaction falls upon the transition through temperature T* ∼ 300°C, above which the electrophysical and crystallographic properties of phosphates change. The observed dependences are explained by the center (which consists of copper with various positions in the phosphate network at T < T* and T > T*) taking part in the formation of carbonyl compounds. This indicates the presence of a ligand effect, i.e., to structural sensitivity of the dehydration reaction in the case of Cu-NZP catalysts.     

Crystal structures of La1 ? xSr2 + x(GeO4)(V1 ? xMoxO4) (x= 0?0.4) solid solutions

The phase compositions of theLaVO₄-SrMoO₄(1) and Sr₂GeO₄-SrMoO₄ (2) binary systems, which bound the Sr₂GeO₄-LaVO₄-SrMoO₄ (3) ternary system, and the LaSr₂(VO₄)(GeO₄)-Sr₂GeO₄+SrMoO₄ section (4) of system 3 are studied at subsolidus temperatures. Systems 1 and 2 consist of a mixture of the initial compounds, and the La_{1 − x} Sr_{2 + x} (GeO₄)(V_{1 − x} Mo _x O₄) (where 0 ≤ x ≤ 0.4) region of substitutional solid solutions with a palmierite structure is formed in system 3. The unit cell parameters of the solid solutions are determined. The distribution of the lanthanum and strontium cations over two positions of the cationic sublattice is described. Original Russian Text ? V.D. Zhuravlev, V.G. Zubkov, A.P. Tyutyunnik, Yu.A. Velikodnyi, N.D. Koryakin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 1, pp. 135–137.     

Ag1 ? xMg1 ? x R1 + x(MoO4)3 Ag+-conducting NASICON-like phases, where R = Al or Sc and 0 ≤ x ≤ 0.5

Ag_{1 − x} Mg_{1 − x} R_{1 + x} (MoO₄)₃ NASICON-like solid solutions, where R = Al or Sc and 0 ≤ x ≤ 0.5, were prepared; their crystal lattice parameters and thermal stabilities were determined. Silver-ion conductivity was measured, and conductivity activation energy values were calculated for various temperature ranges. Above 400°C, Ag_{1 − x} Mg_{1 − x} R_{1 + x} (MoO₄)₃ phases have ionic conductivities comparable to the conductivities of sodium-ion and lithium-ion NASICON-like conductors. The conductivity increases as the tervalent cation radius increases or the amount of mobile silver ions increases.     

Mechanism studies and electrochemical performance optimization on xLiFePO4·(1 ? x)Li3V2(PO4)3 hybrid materials

Hybrid materials xLiFePO₄·(1 − x)Li₃V₂(PO₄)₃ were synthesized by sol–gel method, with phenolic resin as carbon source and chelating agent, methylglycol as surfactant. The crystal structure, morphology and electrochemical performance of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge–discharge test and particle size analysis. The results show that LiFePO₄ and Li₃V₂(PO₄)₃ co-exist in hybrid materials, but react in single phase. Compared with individual LiFePO₄ and Li₃V₂(PO₄)₃ samples, hybrid materials have smaller particle size and more uniform grain distribution. This structure can facilitate Li ions extraction and insertion, which greatly improves the electrochemical properties. The sample 0.7LiFePO₄·0.3Li₃V₂(PO₄)₃ retains the advantages of LiFePO₄ and Li₃V₂(PO₄)₃, obtaining an initial discharge capacity of 166 mA h/g at 0.1 C rate and 109 mA h/g at 20 C rate, with a capacity retention rate of 73.3% and an excellent cycle stability.     

Cationic mobility in Li3?2xNbxFe2?x(PO4)3 complex phosphates

Synthesis and ionic conductivity of Li_3−2x Nb _x Fe_2−x (PO₄)₃ complex phosphates were studied by X-ray powder diffraction and impedance spectroscopy. These phosphates are formed only at 900–1000°C. Variations in their thermal expansivity and unit cell parameters induced by aliovalent doping were characterized. The conductivity of these materials increases monotonically in the series Li_0.5Nb_1.25Fe_0.75(PO₄)₃-LiNbFe(PO₄)₃ and Li_1.2Nb_0.9Fe_1.1(PO₄)₃-Li₃Fe₂(PO₄)₃, which is explained by consecutive occupation of the Li(1) and Li(2) positions in their structures. Original Russian Text ? A.R. Shaikhlislamova, I.A. Stenina, A.B. Yaroslavtsev, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 12, pp. 1957–1962.     

NASICON phases of variable composition K1? x A1? x R1+ x (MoO4)3 (0 ≤ x ≤ 0.2–0.6), where A = Ni, Mg, Co, or Mn and R = Yb, Lu, or Sc

Phases of variable composition K_1−x A_1−x R_1+x (MoO₄)₃) (0 ≤ x ≤ 0.2–0.6), where A = Ni, Mg, Co, or Mn and R = Yb, Lu, or Sc, which crystallize in a NASICON-type structure (space group R c) were synthesized by solid-phase reactions. Their crystal parameters were calculated, and IR and Raman spectra described. Original Russian Text ? N.M. Kozhevnikova, T.N. Khamaganova, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 5, pp. 864–865.     

Li1.3Zr1.7Al0.3(PO4)3的离子交换特性

锂作为21世纪推动科学技术发展的重要元素之一,被誉为“工业味精”、“能源之星”。目前锂及其相关盐类材料已成为信息产业、核能源、航空航天技术、新型材料及军事科技等行业重点开发领域,具有极高科学价值和广阔商业前景[1￣4]。氯化锂是电解制金属锂的主要原料,它的纯度是电     

Phase formation in the Ba3? x Sr x Y(BO3)3 system (0 < x < 3)

Phases of a variable composition in the Ba_3−x Sr _x Y(BO₃)₃, system (0 < x < 3) have been investigated for the first time using the solid-phase reactions method. The formation of two series of solid solutions crystallizing in different structural types have been established using X-ray diffraction (D-8 Advance diffractometer, CuK _α radiation, graphite monochromator). Crystal characteristics of obtained phases have been determined. Original Russian Text ? T.N. Khamaganova, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 4, pp. 553–556.     

Li-cycling properties of nano-crystalline (Ni1 ? xZnx)Fe2O4 (0 ≤ x ≤ 1)

Sol–gel auto-combustion method is adopted to prepare solid solutions of nano-crystalline spinel oxides, (Ni_1 − x Zn _x )Fe₂O₄ (0 ≤ x ≤ 1).The phases are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, selected area electron diffraction, and Brunauer–Emmett–Teller surface area. The cubic lattice parameters, calculated by Rietveld refinement of XRD data by taking in to account the cationic distribution and affinity of Zn ions to tetrahedral sites, show almost Vegard’s law behavior. Galvanostatic cycling of the heat-treated electrodes of various compositions are carried in the voltage range 0.005–3 V vs. Li at 50 mAg⁻¹ up to 50 cycles. Phases with high Zn content x ≥ 0.6 showed initial two-phase Li-intercalation in to the structure. Second-cycle discharge capacities above 1,000 mAh g⁻¹ are observed for all x. However, drastic capacity fading occurs in all cases up to 10–15 cycles. The capacity fading between 10 and 50 cycles is found to be greater than 52% for x ≤ 0.4 and for x = 0.8. For x = 0.6 and x = 1, the respective values are 40% and 18% and a capacity of 570 and 835 mAh g⁻¹ is retained after 50 cycles. Cyclic voltammetry and ex situ transmission electron microscopy data elucidate the Li-cycling mechanism involving conversion reaction and Li–Zn alloying–dealloying reactions.     

Synthesis and study of the properties of K2Y1 ? x ? yEuxTby(MoO4)(PO4) and K2Y1 ? x ? yEuxTby(MoO4)(PO4)1?δ(VO4)δ solid solutions

Al synthesized samples are isostructural and crystallize in the orthorhombic symmetry system, space group Ibca. Particles of the final product of ∼200 nm in size have been obtained. The introduction of the vanadate anion into the matrix composition leads to the lowering of the symmetry of the Eu³⁺ environment and to the rise of the defect luminescence at 450–550 nm because of the unit cell distortion. The luminescence of defects in terbium-europium-containing samples is determined by the sample surface area, which decreases on annealing. The τ, W ₀ and γ parameters of the luminescence kinetics of the samples have been determined.     

Synthesis and study of the variable-composition phase Na1?xCo1?xFe1+x(MoO4)3, 0 ≤ x ≤ 0.4, with nasicon structure

The synthesis conditions for variable-composition phase Na_1−x Co_1−x Fe_1+x (MoO₄)₃, 0 ≤ x ≤ 0.4, crystallizing in the nasicon structure type (R $ \bar 3 $ \bar 3 c) were examined. For this phase, the crystallographic parameters were calculated, vibrational spectra were interpreted, and temperature dependence of electrical conductivity, dielectric constant, and dielectric loss tangent were examined.     

Phases of variable composition in the system Ba3 ? x Sr x Er(BO3)3 (0 ≤ x ≤ 3.0)

The possibility of preparing two series of solid solutions in the system Ba_{3 − x} Sr _x Er(BO₃)₃ (0 ≤ x ≤ 3.0), crystallizing in different structural types, was examined. Samples of the phases of variable composition were synthesized by the method of solid-phase reactions, and their X-ray phase analysis was done. The X-ray diffraction characteristics of the phases synthesized were determined. Original Russian Text ? T.N. Khamaganova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 7, pp. 1210–1212.     

Structure and thermal properties of [Ir(NH3)5Cl]x[Rh(NH3)5Cl]1?xMO4 (x = 0.5, 1; M = Mo, W)

Complex salts [Ir(NH₃)₅Cl]x[Rh(NH₃)₅Cl]_1−x MO₄ (x = 0.5, 1; M = Mo, W) are synthesized and their thermal properties are studied. The crystal structures are determined for [Ir(NH₃)₅Cl]WO₄ and [Ir(NH₃)₅Cl]MoO₄. In the structures, the ions are linked by N-H...O hydrogen bonds, the shortest ones being 2.868(2)–3.422(2) ?. and 2.860(4)–3.434(3) ?. respectively. The thermal properties of the complex salts are studied in the hydrogen atmosphere and in hydrogen-helium mixtures. It is demonstrated that the final products are the mixtures of nanocrystalline powders of Ir and binary or ternary solid solutions with the hcp lattice.     

Structural and electric properties of the Ce0.8(Sm1 ? xCax)0.2O2 ? δ system (x = 0.0–1.0)

CeO₂-based solid solutions with a fluorite structure are promising materials as electrolytes of medium-temperature electrochemical devices. This work presents the results of systematic studies of structural and electric properties and oxygen nonstoichiometry of the Ce_0.8(Sm_{1 − x} Ca _x )_0.2O_{2 − δ} system in a wide range of concentrations of 0 < x < 1 performed in order to establish the causes affecting the system conductivity and its behavior in a reducing medium. It is found that a single-phase solid solution of the fluorite type is formed in the whole concentration range. Parameters of its lattice cells decrease linearly at an increase in the concentration of Ca²⁺. Conductivity in air grows when calcium is added due to a decrease in the grain boundary resistance. The maximum conductivity in air was obtained for the composition of Ce_0.8(Sm_0.8Ca_0.2)_0.2O_{2 − δ} and is 13.71 × 10⁻³ S/cm at 873 K. Studies of the dependence of conductivity of the partial pressure of oxygen showed that electron conductivity is observed at a higher oxygen partial pressure at an increase in the temperature and calcium concentration. The critical partial pressure of oxygen ( p_O2 ^* )\left( {p_{O_2 }^* } \right) for the compositions of Ce_0.8(Sm_{1 − x} Ca _x )_0.2O_{2 − δ} with x = 0; 0.2, and 0.5 is 1.83 × 10⁻¹⁶, 1.73 × 10⁻¹³, and 3.63 × 10⁻¹³ atm at 1173 K, respectively, and 2.76 × 10⁻²¹, 5.05 × 10⁻¹⁸, and 1.31 × 10⁻¹⁸ atm at 1023 K.     

Rare earth metal-rich indides RE 4IrIn ( RE = Gd–Er), RE 4IrInO0.25 ( RE = Gd, Er), and RE 4 T In1– x Mg x ( RE = Y, Gd; T = Rh, Ir)

The rare earth-transition metal-indides RE ₄IrIn (RE = Gd–Er) and the solid solutions RE ₄ TIn_1–x Mg _x (RE = Y, Gd; T = Rh, Ir) were prepared by arc-melting of the elements and subsequent annealing. The rare earth sesquioxides were used as oxygen source for the suboxides RE ₄IrInO_0.25 (RE = Gd, Er). Single crystals of the indides were grown via slowly cooling of the samples and they were investigated via X-ray powder diffraction and single crystal diffractometer data: Gd₄RhIn type, F 3m, a = 1372.3(6) pm for Gd₄IrIn, a = 1365.3(6) pm for Tb₄IrIn, a = 1356.7(4) pm for Dy₄IrIn, a = 1353.9(4) pm for Ho₄IrIn, a = 1344.1(4) pm for Er₄IrIn, a = 1370.3(5) pm for Y₄RhIn_0.54Mg_0.46, a = 1375.6(5) pm for Gd₄IrIn_0.55Mg_0.45, a = 1373.0(3) pm for Gd₄IrInO_0.25, and a = 1345.1(4) pm for Er₄IrInO_0.25. The rhodium and iridium atoms have a trigonal prismatic rare earth coordination. Condensation of the RhRE ₆ and IrRE ₆ prisms leads to three-dimensional networks which leave voids that are filled by regular In₄ or mixed In_4–x Mg _x tetrahedra. The indium (magnesium) atoms have twelve nearest neighbors (3In(Mg) + 9RE) in icosahedral coordination. The rare earth atoms build up a three-dimensional, adamantane-like network of condensed, edge and face-sharing octahedra. For Gd₄IrInO_0.25 and Er₄IrInO_0.25 the RE1₆ octahedra are filled with oxygen. The crystal chemical peculiarities of these rare earth rich compounds are discussed. Correspondence: Rainer P?ttgen, Institut für Anorganische und Analytische Chemie, Westf?lische Wilhelms-Universit?t Münster, Germany.     

New synthesis of pure CexZr1?xO2 mixed oxides (0?≤?x?≤?1) by an epoxide sol–gel method

Pure ceria-zirconia mixed oxides Ce _x Zr_1−x O₂ with high specific surface area were synthesized with a new epoxyde driven sol–gel route and characterized by thermal analysis, X-ray diffraction studies and transmission electron microscopy. This sol–gel method is cheap and uses only a few steps. The Ce _x Zr_1−x O₂ mixed oxides were obtained in the range of 0 ≤ x ≤ 1 (except for x = 0.8) and crystallised at 350 °C after decomposition of the gels. This temperature is very low in comparison with the other methods. The studies of the influence of different synthesis parameters (concentration of the sol and decomposition temperature) allowed us to determine the conditions to obtain the best homogeneity in the gel to avoid the formation of a mixture of phases instead of mixed oxides. This approach leads to the synthesis of oxide with specific surface area above 100 m² g⁻¹. The elaboration of an ambigel could increase this value up to 195 m² g⁻¹ for x = 0.5. This sol–gel synthesis offers new perspectives for these oxides in several applications. Generally, these oxides are difficult to obtain pure in large range of composition at low-temperature and with high specific surface area by other methods.