Electroconductance of single-crystal Li2 + x Fe 2 − 2x 2+ Fe x 3+ (MoO4)3 (x = 0.22)

Electrophysical properties of single-crystal Li_{2 + x} Fe _{2 ? 2x} ²⁺ Fe _x ³⁺ (MoO₄)₃ (x = 0.22) are studied at 25–400°C. It is found that the conduction is of electronic nature and the conductivity equals 5 × 10^-2 S/cm at 300°C. The activation energy for the electron transport is 0.23 eV. The conductance in molybdate Li_2.22Fe _1.56 ²⁺ Fe _0.22 ³⁺ (MoO₄)₃ is markedly anisotropic.     

High-pressure synthesis and local structure of corundum-type In(2-2x)Zn(x)Sn(x)O(3) (x ≤ 0.7)

The corundum-type In(2-2x)Zn(x)Sn(x)O(3) solid solution (cor-ZITO, x ≤ 0.7) was synthesized at 1000 °C under a high pressure of 70 kbar. cor-ZITO is a high-pressure polymorph of the transparent conducting oxide bixbyite-In(2-2x)Zn(x)Sn(x)O(3) (x ≤ 0.4). Analysis of the extended X-ray absorption fine structure suggests that significant face-sharing of Zn and Sn octahedra occurs, as expected for the corundum structure type. In contrast to the ideal corundum structure, however, Zn and Sn are displaced and form oxygen bonds with lengths that are similar to those observed in high-pressure ZnSnO(3). Powder X-ray diffraction patterns of cor-ZITO showed the expected unit cell contraction with increased cosubstitution, but no evidence for ilmenite-type ordering of the substituted Zn and Sn. A qualitative second harmonic generation measurement, for the solid solution x = 0.6 and using 1064 nm radiation, showed that Zn and Sn adopt a polar LiNbO(3)-type arrangement.     

Li5SnP3 – a Member of the Series Li10+4xSn2−xP6 for x=0 Comprising the Fast Lithium-Ion Conductors Li8SnP4 (x=0.5) and Li14SnP6 (x=1)

The targeted search for suitable solid-state ionic conductors requires a certain understanding of the conduction mechanism and the correlation of the structures and the resulting properties of the material. Thus, the investigation of various ionic conductors with respect to their structural composition is crucial for the design of next-generation materials as demanded. We report here on Li₅SnP₃ which completes with x=0 the series Li_10+4xSn_2−xP₆ of the fast lithium-ion conductors α- and β-Li₈SnP₄ (x=0.5) and Li₁₄SnP₆ (x=1). Synthesis, crystal structure determination by single-crystal and powder X-ray diffraction methods, as well as ⁶Li, ³¹P and ¹¹⁹Sn MAS NMR and temperature-dependent ⁷Li NMR spectroscopy together with electrochemical impedance studies are reported. The correlation between the ionic conductivity and the occupation of octahedral and tetrahedral sites in a close-packed array of P atoms in the series of compounds is discussed. We conclude from this series that in order to receive fast ion conductors a partial occupation of the octahedral vacancies seems to be crucial.     

Kinetics of phase transition and thermal stability in Se80?x Te20Zn x (x?=?2, 4, 6, 8, and 10) glasses

Se_80?x Te₂₀Zn _x (x?=?2, 4, 6, 8, and 10) glasses have been prepared using conventional melt quenching technique. The kinetics of phase transformations (glass transition and crystallization) have been studied using differential scanning calorimetry (DSC) under non-isothermal condition at five different heating rates in these glasses. The activation energy of glass transition (E _t), activation energy of crystallization (E _c), Avrami exponent (n), dimensionality of growth (m), and frequency factor (K _o) have been investigated for the better understanding of growth mechanism using different theoretical models. The activation energy is found to be highly dependent on Zn concentration. The rate of crystallization is found to be lowest for Se₇₀Te₂₀Zn₁₀ glassy alloy. The thermal stability of these glasses has been investigated using various stability parameters. The values of these parameters were obtained using characteristic temperatures, such as glass transition temperature T _g, onset crystallization temperature T _c, and peak crystallization temperature T _p. In addition to this, enthalpy-released during crystallization has also been determined. The values of stability parameters show that the thermal stability increases with the increase in Zn concentration in the investigated glassy samples.     

水热法制备富锂型Li_(2+4x)Mn_(0.6+2x)Ni_(0.6-6x)Cr_(0.8)O_4及其结构与电化学特性

采用水热法制备了系列富锂尖晶石型正极材料Li2+4xMn0.6+2xNi0.6-6xCr0.8O4(x=1/30,1/20,1/15,1/12),通过X射线衍射(XRD)、电感耦合等离子体-原子发射光谱(ICP-AES)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FTIR)、拉曼光谱、循环伏安(CV)和充放电测试等手段对其结构及电化学性能进行表征.结果表明,所制备的系列材料为富锂型高电压尖晶石结构正极材料,该系列样品在4.7 V左右有放电平台.x=1/15和x=1/12时,样品中的Cr为+3价,没有观测到Cr6+.随着x值的增大,样品中Li离子与过渡金属离子的混排减小,样品的充放电比容量逐渐增大,且2.7 V处的放电平台容量也增加.当x=1/12时,样品具有较好的充放电比容量和倍率特性,首次放电比容量为107.3 mA·h/g,20次循环后容量保持率为84.9%.     

Germanium selenophosphates: the incommensurately modulated 1/∞[Ge(4-x)P(x)Se12(4-)] and the molecular [Ge2P2Se14]6-

The new germanium selenophosphates K(4)Ge(4-x)P(x)Se(12) (1) and Rb(6)Ge(2)P(2)Se(14) (2) are reported. The former is a one-dimensional metastable compound synthesized using the polychalcogenide flux method that crystallizes in the monoclinic space group P2(1)/c with lattice parameters a = 6.7388(7) ?, b = 13.489(1) ?, c = 6.3904(6) ?, and β = 91.025(8)°. At a glance, a mixed Ge(4+)/P(5+) tetrahedral site and disordered Se position are found among the corner sharing tetrahedra that make up the polymeric anion. After careful examination, the structure was found to be incommensurately modulated and a single q-vector of q = 0.4442(6)a* + 0.3407(6)c* was determined after annealing single crystals below their decomposition point for 30d. The latter compound contains the new discrete molecular anion [Ge(2)P(2)Se(14)](6-) and crystallizes in P1 with lattice parameters a = 7.2463(8) ?, b = 9.707(1)?, c = 11.987(1)?, α = 79.516(9)°, β = 89.524(9)°, and γ = 68.281(9)°. Both compounds are semiconductors with band gaps of 1 and 2 being 1.9 eV and 2.2 eV, respectively.     

Magnetic phase transformation induced by electrochemical lithium intercalation in Li1 + x EuTiO4 and Li2 + 2x Eu2Ti3O10 (0 ≤ x ≤ 1) compounds

Ion exchange of Li for Na in the layered compounds NaEuTiO₄ and Na₂Eu₂Ti₃O₁₀ transforms the (NaO)₂ rock-salt layers into Li₂O₂ antifluorite layers. Li can be inserted reversibly into the Li₂O₂ layers to reduce the Eu³⁺ to Eu²⁺, not the Ti(IV) to Ti(III). An internal electric field perpendicular to the layers is reduced by Li insertion; this field induces a ferroic displacement of the Ti(IV) toward the alkali-ion layers that is eliminated as the internal electric field vanishes in Li_2?+?2x Eu₂Ti₃O₁₀ with x?≈?1. The spins of the (EuO)₂ and the (EuTiO₃)₂ bilayers of Li_1?+?x EuTiO₄ and Li_2?+?2x Eu₂Ti₃O₁₀ with x?≈?1 order at low temperature into ferromagnetic Eu–Eu chains that form a 2D ferromagnetic spiral spin configuration in zero magnetic field. The M-H curve shows zero coercivity and zero remanence, but the M of a polycrystalline sample rises to 4 μ_B/Eu in an H?=?1 T and approaches saturation above 5 μ_B/Eu in 5 T.     

喷雾干燥法制备Li_(1.2)Mn_(0.4+x)Ni_xCr_(0.4-2x)O_2及其结构与电化学特征

利用喷雾干燥法合成了富锂三元正极材料Li1.2Mn0.4+xNixCr0.4-2xO2(x=0,0.05,0.10,0.15,0.20,以下简称为SD1~SD5),并利用XRD,XPS,ICP,TEM,SEM等手段对材料进行结构,元素价态,形貌及电化学性能等方面的表征。SD1~SD5系列样品都具有层状结构,其所含的Cr元素为Cr6+和Cr3+共存,而Ni元素价态为+2.5价,Mn元素为+4价。SD1~SD4样品中由于存在非晶态的Li2CrO4,导致样品表现出强烈的吸湿性。这个问题可通过水洗处理来解决,且水洗处理对于改善该系列材料的电化学性能有明显的效果。SD1~SD5系列样品中,SD1与SD4样品电化学性能较好,以20 mA.g-1的放电电流密度,在4.8~2.0 V电压区间内,首次放电比容量分别为247和220 mA.h.g-1,经过20次充放电循环后,容量保持率分别为73%和78%。高温条件下SD1和SD4样品的首次放电比容量分别增大为256和237 mA.h.g-1,经过20次充放电循环后容量保持率分别为83%和99%。将充放电电压扩展为5.0~2.0 V时,SD4样品首次放电比容量可以达到307 mA.h.g-1。     

Ca2+xLa8-x(SiO4)6O2-0.5x的合成及其导电机理

Ca2+xLa8-x(SiO4)6O2-0.5x的合成及其导电机理;溶胶凝胶法;硅酸盐氧基磷灰石;空位导电机理;电化学阻抗谱     

Cu(phen)2+2和Cu(bpy)2+2与6-巯基嘌呤、腺嘌呤相互作用的研究

在ｐＨ为７．０的磷酸盐缓冲溶液中，用荧光光谱、紫外光谱、电化学及紫外光谱电化学等方法研究了铜配合物与６－巯基嘌呤、腺嘌呤的相互作用．结果表明，Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤发生了相互作用，但作用程度不同．根据荧光光谱实验数据计算出Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤的配位比均为１∶１；它们与６－巯基嘌呤作用的配位常数分别为２．２３×１０４Ｌ／ｍｏｌ和６．１１×１０４Ｌ／ｍｏｌ；与腺嘌呤作用的配位常数分别为１．９５×１０４Ｌ／ｍｏｌ和５．１２×１０４Ｌ／ｍｏｌ．电化学实验也获得了相近的结果．这为解释Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与ＤＮＡ的作用机理及作用部位提供了有益的信息     

Bioresorbable carbonated hydroxyapatite Ca10−xNax(PO4)6−x(CO3)x(OH)2 powders for bioactive materials preparation

The purpose of this work was to find and investigate a correlation between the carbonate ion content in crystalline lattice and defect structure, and solubility of the materials; finally, to prepare the materials under study for in vitro tests. Various techniques, such as XRD, FTIR, TEM, FESEM/EDX, TG/DTA, AES (ICP), wet chemical analysis, Ca-ionometry, microvolumetric analysis of evolved CO₂, BET adsorption, were applied to determine the efficiency of carbonate substitution, and to quantify the elemental composition, as well as to characterize the structure of the carbonated hydroxyapatite and the site(s) of carbonate substitution,. It was shown that AB-type substitution prevails over other types with the carbonate content increase. According to in vitro tests, the bioactivity of the samples is correlated with the carbonate content in carbonate-doped hydroxyapatite due to accumulation of defects in carbonated hydroxyapatite nanocrystals.      

Two-step hydrothermal synthesis of submicron Li(1+x)Ni(0.5)Mn(1.5)O(4-δ) for lithium-ion battery cathodes (x = 0.02, δ = 0.12)

A facile two-step hydrothermal method is developed for the large-scale preparation of lithium nickel manganese oxide spinel as a cathode material for lithium ion batteries. In the reaction, nickel is introduced in a first step at neutral pH, followed by lithium insertion under base to form a product having composition Li(1.02)Ni(0.5)Mn(1.5)O(3.88). The X-ray diffraction pattern and Raman spectroscopy of the synthesized material support a cubic Fd3m structure in which Ni and Mn are disordered on the 16d Wyckoff site, necessary for good cycling characteristics. XP spectroscopy and elemental analysis confirms that Mn remains reduced in the final product (Z(Mn) = 3.82) and that two different chemical environments for Ni exist on the surface. SEM imaging shows a primary particle size of ~200 nm, and galvanostatic cycling of the material vs. Li(+/0) gives a reversible gravimetric capacity of ~120 mA h g(-1) at 1 C rate (147 mA g(-1)) with reversible cycling up to 1470 mA g(-1), supported by rapid Li(+) diffusion. The capacity fade at 1 C is substantial, 17.3% over the first 100 cycles between 3.4 and 5.0 V. However, when the voltage limits are altered, the capacity retention is excellent: nearly 100% when cycled either between 3.4 and 4.4 V (where oxygen vacancies are not electrochemically active) or 89% when cycled between 4.4 and 5.0 V (where the Jahn-Teller active Mn(4+/3+) couple is not accessed).     

THE CRYSTAL STRUCTURE OF A NOVEL TETRANUCLEAR SILVER CLUSTER COMPLEX Ag_4(α-C_(10)H_7CS_2)_4(Py)_4·2Py

The title compound has been synthesized by the reaction of α-dithionaphthoic acidwith AgNO_3 in an organic solvent. The single crystals were obtained by recrystallizingfrom pyridine. We obtained two kinds of crystal with different colours (A and B), usingdifferent ratios of silver nitrate and α-dithionaphthoic acid (1:2,1:4) in the reactions. The structures of the two kinds of crystal were determined by a single-crystal X-raydiffraction analysis. The crystal (A) belongs to monoclinic space group C_(2h)~5-P2_1/a withunit cell parameters: a = 22.822(4) A, b = 12.803 (4) A, c = 24.444 (7) A, β = 103.90 (2)°V = 6933.14 A~3, Z = 4. The crystal (B) belongs to monoclinic space group C_(2h)~6-C2/c witha = 29.150 (2) A, b = 12.799 (3) A, c = 24.413 (2) A, β = 130.56 (4)°, V = 6914.38 A~3,Z = 4. Both crystals (A) and (B) have the same molecular configuration, but they havedifferent symmetry. In crystal (B), the molecule possesses a C_2 symmetry. This paperreports the structure determination and parameters o     

THE SYNTHESIS AND CRYSTAL STRUCTURE OF A NOVEL MOLYBDENUM-COPPER-SULFUR CLUSTER COMPOUND [(CH_3CH_2 )_4N]_2 [(μs-S)CusS_6(S_2)_6Mo_6O_6].DMF

The synthesis and crystal structure of a novel molybdenum-copper cluster compound with [(μs-S)Cus] core is reported. It was prepared from Cu2Br2 upon reaction with molybdenum sulfur compound [CH3CH2)4N]2[Mo2O2S2-(S2)(S4)]. The title compound crystallizes in the monoclinic system space group Cc with cell dimensions: a=21.320(5), b=21.869(3), c=13.029(5)A,β=118.28(1)°,Z=4, V=5349A3 and Dc=2.48 g.m-3. The structure has been determined by Patterson and Fourier methods and then refined by the least squares method to a final R of 0.053. There are some distortions from octahedron in configuration of the [(μs-S)Cu6]6 core with three weak Cu-Cu bonds.     

锂离子电池正极材料Li(1-2x)MgxMnPO4/C的合成与表征

采用溶胶凝胶法合成前驱体,再在空气气氛中分别于400℃、500℃和600℃下焙烧,得到锂离子电池正极材料(1-2x)MgxMnPO4/C(0≤x≤0.1);利用X射线衍射分析、环境扫描电镜分析、恒流充放电、阻抗测试等分析了产物的结构、形貌和电化学性能.结果表明,合成的(1-2x)MgxMnPO4/C颗粒呈球形,具有橄榄...     

Thermal studies on Li(CH3CN)4PF6 and Li(C4H10O2)2PF6 complexes by the TG–DTA–MS and DSC

Journal of Thermal Analysis and Calorimetry - Li(CH3CN)4PF6 and Li(C4H10O2)2PF6 complexes are important intermediates created in the synthetic process of high-purity LiPF6 electrolyte via...     

SYNTHESIS,CHARACTERIZATION, AND CRYSTAL STRUCTURE OF A NOVEL DECAVANADATE Mg(H2O)6(C6H14N2)2V10O28·8H2O

Journal of Structural Chemistry - A novel decavanadate salt Mg(H2O)6(C6H14N2)2V10O28·8H2O is obtained by the reaction of vanadium oxide and 1,4-diazabicyclo [2.2.2] octane (DABCO). The title...     

How Do G–Se Nonbonded and Y–Se Through π -Bond Interactions Determine the Structures of 8-G-1-( p-YC6H4Se)C10H6?

Abstract

Structures of 8-G-1-( p-YC ₆ H ₄ Se)C ₁₀ H ₆ (G = H (1), SeMe (2), Cl (3), and Br (4)) bearing various Y are determined by the X-ray crystallographic analysis. While Y dependence in the structures originates from the through π interaction between n _p (Se) and n _p (Y), G dependence is based on the nonbonded n _p (G)…σ*(Se–C) 3c–4e interaction. QC calculations reveal that the specific stability appears when the π 2c–4e is distorted (Möbius type stability).