Polarized infrared and neutron scattering studies of α-Bi2O3

Studies on the lattice dynamics of -Bi₂O₃ have been performed including IR polarized reflectance spectra on single crystal, inelastic neutron scattering and specific heat measurements. Dispersion parameters and polarizations of IR-active phonons are presented and compared with neutron and specific heat data.     

Zn3V2O7(OH)2·2H2O and Zn3(VO4)2 3D microspheres as anode materials for lithium-ion batteries

Three-dimensional Zn₃V₂O₇(OH)₂·2H₂O microspheres have been successfully synthesized by a simple and facile liquid phase precipitation method without using any surfactants or additives. The as-prepared microspheres were constructed by two-dimensional nanosheets, which interconnected with each other through self-assembly. The influences of the aging time, reaction temperature, and pH value on the morphologies of the products were systematically investigated. Moreover, three-dimensional Zn₃(VO₄)₂ microspheres could be formed through calcination of the Zn₃V₂O₇(OH)₂·2H₂O precursor. The obtained Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ microspheres were further investigated as the anode materials of lithium-ion batteries. Electrochemical measurements showed that the Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ microspheres exhibited high discharge capacity and good cycle stability, indicating potential anode candidates in advanced rechargeable lithium-ion batteries. It should be noted that this is the first report on the Zn₃V₂O₇(OH)₂·2H₂O and Zn₃(VO₄)₂ three-dimensional microspheres as anode materials in lithium-ion batteries. The present work will greatly expand the range of anode choices and could assist long-term endeavors in developing high capacity anode materials for lithium-ion batteries.     

3D hierarchical Zn3(OH)2V2O7·2H2O and Zn3(VO4)2 microspheres: Synthesis,characterization and photoluminescence

Via a simple glycine-assisted hydrothermal route, large-scale 3D hierarchical Zn₃(OH)₂V₂O₇·2H₂O microspheres have been fabricated. Their purity, crystalline phase, morphologies and thermal stability were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform IR (FTIR), scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The SEM results indicate that the microspheres are self-assembled by numerous nanoflakes with mean thickness of 100 nm. Some factors influencing the morphologies of the Zn₃(OH)₂V₂O₇·2H₂O micro-/nanostructures have been systematically investigated, as well as quantity of glycine and the reaction time. The possible mechanism of the crystal growth and assembled procedure were also proposed. The as-prepared Zn₃(OH)₂V₂O₇·2H₂O can be transformed into Zn₃(VO₄)₂ with the similar morphologies by calcination in air at 600 °C. Furthermore, the photoluminescent properties of both Zn₃(OH)₂V₂O₇·2H₂O and Zn₃(VO₄)₂ were studied and exhibited different spectra.     

Electronic conductivity of Sr3-3xLa2x█x(VO4)2 solid solutions

The electronic conductivity of Sr_3-3xLa_2x█_x(VO₄)₂ solid solutions was measured at oxygen pressures from 10^-13 to 10⁵ Pa and temperatures from 1070 to 1270 K, and their band gap was determined as a function of composition. The activation energy (≏2.85 eV) and enthalpies of electron generation (≏4.2 eV) and migration (≏0.75 eV) were determined. A correlation between the band gap and electronic conductivity of the solid solutions was revealed     

控制NH4VO3分解及产物间反应制备VO2的研究

VO2是一种温感相变材料,68℃左右它从低温半导体相向高温金属相转变,同时其光学和电学性质发生突变.由于V与O之间可以形成任意化学配比的VxOy,,所以纯VO2的制备过程复杂难以控制.采用单一原料NH4VO3,在化学计量反应计算的基础上将其装入刚玉坩埚,置于特制的高压釜中,升温至1000K,反应60min,自然冷却得蓝黑色VO2样品.利用X射线衍射、扫描电镜和差示扫描量热法对样品进行表征与测试.结果表明,所制备的样品为VO2多晶粉末.粒度为几至几十微米,具有相变特性.相变温度为343.53K,相变过程是吸热过程,相变焓为43.75J/g.目前,该方法是合成VO2研究中最简单易行的方法.     

Ca3(VO4)2–LaVO4 Cation Conductors

Experimental data are presented on the electrical conductivity, ionic transference numbers, and phase transitions of Ca_{3 – x} La_2x/3(VO₄)₂ (0 x 1) vanadates, which are shown to be Ca ionic conductors. The highest Ca ion conductivity is found in Ca₂La_2/3(VO₄)₂ (palmierite structure) at low temperatures and in "-Ca₃(VO₄)₂ (whitlockite-like structure) at high temperatures. The mechanisms of Ca²⁺ transport are discussed.     

The thermal decomposition mechanism of iron(III) hydroxide carbonate to α-Fe2O3

The thermal decomposition mechanism of iron(III) hydroxide carbonate prepared through hydrolysis and oxidation of FeCO₃ is studied under both static and dynamic conditions. It is established that the precursor is decomposed to -Fe₂O₃ forming an intermediate phase, -FeOOH. Up to 523 K the structural transformations proceed with limited cation diffusion which leads to the pseudomorphic formation of Fe₂O₃ with large specific area.     

Crystal structure of a double Np(V) ammonium propionate, NH4[(NpO2)3(C2H5COO)4(H2O)]·3H2O

The structure of NH₄[(NpO₂)₃(C₂H₅COO)₄(H₂O)]·3H₂O was studied by single crystal X-ray diffraction. The single crystals were prepared by hydrothermal synthesis. In the structure, there are three crystallographically independent Np atoms with different equatorial surrounding. All of them have CN 7; the coordination polyhedron is a distorted pentagonal bipyramid. Each NpO ₂ ⁺ cation is bonded to four other cations, acting simultaneously as a bidentate ligand and a coordination center for two other dioxocations. The cation-cation interactions result in formation of trigonal-hexagonal cationic networks.     

Synthesis of Double Uranyl Phthalates of the M4[(UO2)4(μ3-O)2(C6H4C2O4)4] ⋅ nH2O Type with M = NH4, K, and Cs. Crystal Structure of K4[(UO2)4O2(C6H4C2O4)4] ⋅ 3H2O

Double U(VI) phthalates with NH ₄ ⁺ , K⁺, and Cs⁺ ions in the outer sphere were synthesized. The X-ray phase analysis shows that their structures are similar. Single crystals were prepared and the structure of K₄[(UO₂)₄(μ₃-O)₂(C₆H₄C₂O₄)₄] ? 3H₂O was solved. In the [(UO₂)₄O₂(C₆H₄C₂O₄)₄]^4? anions forming the main structural motif, each bridging oxygen atom μ₃-O combines one pentagonal and two hexagonal bipyramids, which, in turn, are combined in centrosymmetrical tetramers. The phthalate ions have coordination capacity equal to 3; each ligand coordinates U(1) in the bidentate fashion via one carboxy group and U(2) in the bidentate fashion to form a planar seven-membered chelate ring.     

Soft mechanochemical synthesis of MgFe2O4 nanoparticles from the mixture of α-Fe2O3 with Mg(OH)2 and Fe(OH)3 with Mg(OH)2

Abstract

The influence of long term soft milling of a mixture of (1) Mg(OH)₂ and α-Fe₂O₃ and (2) Mg(OH)₂ and Fe(OH)₃ powders in a planetary ball mill on the reaction synthesis of nanosized MgFe₂O₄ ferrites was studied. Soft mechanochemical reaction leading to formation of the MgFe₂O₄ spinel phase was followed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and magnetisation measurements. The spinel phase formation was first observed after 5 h of milling and its formation was completed after 15 h in case (2). The synthesised MgFe₂O₄ ferrite had a nanocrystalline structure with a crystallite size of about 10 and 15 nm respectively for cases (1) and (2). Measurements after 15 h of milling show magnetisation values of 15·23 and 10·14 J T^–1 kg^–1 respectively for cases (1) and (2).     

Hydrothermal synthesis of mixed phosphates of neodymium and alkaline metals (Me2O·Nd2O3·4P2O5)

The phase formation in the system Me₂O-Nd₂O₃-P₂O₅-H₂O (where Me = Li, Na, K, Rb and Cs) has been studied under hydrothermal conditions in the temperature and pressure range 300 to 700 C and 0.5 to 600 atm, respectively, using vitreous carbon glass liners. A composition diagram showing the possible fields of crystallization of different phases under equilibrium conditions is given. AB-diagrams of fields of crystallization of different phases in the system investigated are given. These diagrams are in correspondence with the theoretical composition diagram. The advantages and disadvantages of different methods employed in the growth of MeNd-phosphates are discussed. The crystals obtained were characterized by various methods.     

Conductivity of (NH4)3[CrMo6O24H6]·7H2O Treated by Nd Chemistry-Heated Diffused Permeation

Rare earth co-permeation of (N H4)3 [CrMo6 O24 H6]·7H2O was reported and the conductivity of (N H4)3 [CrMo6O24 H6]was improved by 6.734× 109 times. X-ray fluorescence spectrometry (XRF), thermogravimetry-differential thermal sample. Experimental results showed that Nd could be permeated into the body of this sample and the XRD patterns showed great difference between (NH4)3[CrMo6O24H6]·7H2O and permeated sample. The structure of (NH4)3[CrMo6O24H6]·7H2O was destroyed and new compound MoN perhaps formed.     

Ceramics Based on CaSO4⋅2H2O Powder Synthesized from Ca(NO3)2 and (NH4)2SO4

Inorganic Materials - Ceramics consisting of anhydrous calcium sulfate, CaSO4, after firing in the range 800–1000°C have been prepared from calcium sulfate dihydrate (CaSO4?2H2O)...     

[Mn(H2P2O7)3]3-引发淀粉-MMA-VAc接枝共聚反应的研究

以焦磷酸锰络阴离子[Mn(H2P2O7)3]3-为引发剂,采用溶液聚合的方法合成了淀粉-甲基丙烯酸甲酯-聚醋酸乙烯酯(S-MMA-VAc)接枝共聚物.用红外光谱(IR)及高效凝胶渗透色谱(HPGPC)对接枝共聚物的结构进行了表征.探讨了pH值、引发剂浓度、单体浓度、单体比例等因素对接枝率(G)和接枝效率(GE)的影响,获得了最佳的反应条件.同时发现,该反应中均聚物及MMA-co-VAc共聚物的生成不仅可由引发剂直接引发,还可能因淀粉自由基或淀粉接枝物自由基的链转移而引发.     

Synthesis of maghemite (γ-Fe2O3) nanoparticles by thermal-decomposition of magnetite (Fe3O4) nanoparticles

In this research work, we prepared γ-Fe₂O₃ nanoparticles by thermal-decomposition of Fe₃O₄. The Fe₃O₄ nanoparticles were synthesized via co-precipitation method at room temperature. This simple, soft and cheap method is suitable for preparation of iron oxide nanoparticles (γ-Fe₂O₃; Fe₃O₄). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer and differential scanning calorimeter (DSC). The XRD and FT-IR results indicated the formation of γ-Fe₂O₃ and Fe₃O₄ nanoparticles. The TEM images showed that the γ-Fe₂O₃ and Fe₃O₄ were spherical, and their size was 18 and 22 nm respectively. Magnetic properties have been measured by VSM at room temperature. Hysteresis loops showed that the γ-Fe₂O₃ and Fe₃O₄ nanoparticles were super-paramagnetic.     

[Mn(H2P2O7)3]3-引发淀粉与丙烯腈和AMPS接枝共聚

首次以[Mn(H2P2O7)3]3-为引发剂,研究了淀粉与丙烯腈和2-丙烯酰胺-2-甲基丙磺酸(AMPS)接枝共聚反应,并用红外光谱和元素分析法证明了接枝共聚物的存在,并考察了皂化后接枝产物的吸水性随反应条件的变化.结果显示,最适宜的反应条件为单体中AMPS的摩尔百分含量为5%;单体/淀粉的摩尔比为1.5;[Mn(H2P2O7)3]3-浓度2.0×10-3 mol/L;反应温度30 ℃.     

Cobalt-mediated synthesis of 2-(4-pyridyl)benzimidazole. x-ray structures of Co[2-(4-pyridyl)benzimidazole]2(H2O)2(NO3)2 and [Co(isonicotinate)(4-pyridiniumcarboxylate)(H2O)(NO3)]∞

We have observed an unusual example of cobalt-mediated cyclization of 4-pyridinecarboxaldehyde and 2-nitroaniline to afford 2-(4-pyridyl)benzimidazole under hydro(solvo)thermal conditions. Reaction of Co(NO₃)₂·6H₂O with 4-pyridinecarboxaldehyde and 2-nitroaniline in ethanol at 120°C gave a cobalt(II) coordination compound, Co[2-(4-pyridyl)benzimidazole]₂(H₂O)₂(NO₃)₂, 1. In contrast, when the hydro(solvo)thermal reaction was carried out between Co(NO₃)₂·6H₂O and isonicotinic acid in the presence of 2-nitroaniline at 110°C, a one-dimensional Co(II) coordination polymer with the formula of [Co(isonicotinate)(4-pyridiniumcarboxylate)(H₂O)(NO₃)]_∞, 2, resulted. The X-ray single crystal structures of both 1 and 2 are described. Interestingly, the isonicotinic acid in 2 exists as a 4-pyridiniumcarboxylate tautomer, and the pyridinium hydrogen atom forms a very strong hydrogen bond to the carboxylate oxygen of the 4-pyridiniumcarboxylate on an adjacent metal center. 1 forms a three-dimensional polymeric network through hydrogen bonding interactions, while 2 exists as a 2-D bilayer polymeric network through hydrogen bonding interactions.     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: The inclusion compounds [Y(H2O)3]2 (C6Cl2O4)3·6.6H2O and [Y(H2O)3]2 (C6Br2O4)3·6H2O

Single crystal of [Y(H₂O)₃]₂ (C₆Br₂O₄)₃·6H₂O and [Y(H₂O)₃]₂ (C₆Cl₂O₄)₃·6.6H₂O were grown in aqueous silicagel. The compounds are in principle isostructural. In Y chloranilate one additional water site is occupied as verified by X-ray single crystal structure analysis. Y³⁺ is nine-coordinated by three water molecules and six oxygen atoms of the bischelating (C₆X₂O₄)²⁻ ions (XCl, Br). The coordination polyhedron is an only slightly distorted tri-capped trigonal prism. The connection of Y³⁺ with the dianions leads to infinite, corrugated layers. The layer stacking yields cage-like cavities in which water molecules are accomodated. Hydrogen bonds interlink adjacent layers. Further hydrogen bonds involve the entrapped water molecules. DSC measurements indicated a complicated dehydration process which caused right at the start destruction of the single crystals.