Vapour-liquid equilibria in the ternary mixtures N2---CH4---C2H6 and N2---C2H6---C3H8

A systematic study was performed with mixtures consisting of N₂, CH₄, C₂H₆ and C₃H₈, to investigate experimentally phase equilibria and caloric properties and to test the accuracy of thermodynamic correlations. The first part of this Paper reports results of T---p---x---y measurements on ternary systems in the range 20 < p < 120 bar and 140 < T < 220 K. The results are compared with data calculated by generalized equations of state.     

Formation of rod-crystals on CuInSe2 thin films by SILAR method using CH3-(CH2)11-C6H4-SO3Na surfactant

The formation of rod-crystals was observed on CuInSe₂ thin films prepared by successive ionic layer adsorption and reaction (SILAR) method using sodium dodecylbenzene sulfonate (SDBS) as directing agent. Rod-crystals appeared on the surface of CuInSe₂ thin film when adding SDBS into cationic precursor solution. FESEM, EDS, XRD and HRTEM were used to characterize the rod-crystals. The length of rod-crystals has a proportional relationship with SDBS amounts in the given scope of 0.001-0.01 mol/L. The stoichiometry of rod was close to 1:1:2 of CuInSe₂, and rod growth of partially preferential orientation along [112] was observed. The growth of rod could be explained by steric hindrance effects of SDBS adsorbed on the inorganic deposit surface.     

Synthesis and crystal sructure of a new dihydrogenomonophosphate (4-C2H5C6H4NH3)H2PO4

Chemical preparation, crystal structure, calorimetric, and spectroscopic investigations are given for a new organic-cation dihydrogenomonophosphate, (4-C₂H₅C₆H₄NH₃)H₂PO₄ in the solid state. This compound crystallizes in the orthorhombic space group Pbca with the following unit cell parameters: a=8.286(3) Å, b=9.660(2) Å, c=24.876(4) Å, Z=8, V=1991.2(7) Å³, and D_X=1.442 g cm⁻³. Crystal structure was solved with a final R=0.054 for 3305 independent reflections. The atomic arrangement coaled described as H₂PO₄⁻ layers between which are located the 4-ethylanilinium cations.     

Phase equilibria in the liquid ternary system [Y(NO3)3(TBP)3]-[UO2(NO3)2(TBP)2]-C14H30 at different temperatures

The phase diagrams of the ternary system [Y(NO₃)₃(TBP)₃]-[UO₂(NO₃)₂(TBP)₂]-tetradecane in the temperature range 298.15–333.15 K were constructed. These diagrams contain the field of homogeneous solutions and the field of separation into two liquid phases (I, II). Phase I is enriched in [Y(NO₃)₃(TBP)₃] and [UO₂(NO₃)₂(TBP)₂], and phase II is enriched in tetradecane. With increasing temperature, the two-phase fields contract. The critical points of the ternary liquid systems depend on temperature. In the two-phase systems, [UO₂(NO₃)₂(TBP)₂] is preferentially distributed in phase I, although the binary system [UO₂(NO₃)₂(TBP)₂] tetradecane is homogeneous over the entire temperature range. Original Russian Text ? V.A. Keskinov, V.V. Lishchuk, A.K. Pyartman, 2007, published in Radiokhimiya, 2007, Vol. 49, No. 5, pp. 417–419.     

Hydrothermal phase equilibria studies in Ln2O3H2O systems and synthesis of cubic lanthanide oxides

Phase diagrams for the systems Ln₂O₃H₂O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu and Y) studied at 5000 to 10,000 psi and temperature range of 200–900°C, show that Ln(OH)₃ hexagonal and LnOOH monoclinic are the only stable phases from Nd to Ho. The cubic oxide phase (CLn₂O₃) is stable for systems of Er, Tm, Yb and Lu, with no evidence of its equilibrium in the systems of lighter lanthanides. Using strong acids, HNO₃ and HCOOH, as mineralisers the cubic oxides could be stabilised from Eu down to Lu. Solid solution phases of CeO₂Y₂O₃ and Eu₂O₃Y₂O₃ have also been synthesised with HNO₃ as mineraliser, since these compounds have promising use as solid electrolyte and phosphor materials respectively.     

N2 O-C2 H4预混气体火焰的传播特性

运用标准k-ε模型,对N₂O-C₂H₄预混气体在水平半封闭管道内火焰传播过程进行了数值模拟,得到了火焰锋面结构、传播速度、出口压力和燃烧区的气流速度随时间的变化规律。研究结果表明,管道内预混火焰传播过程分为3个阶段:点火初期的平面火焰传播阶段、Tulip火焰传播阶段和指形火焰传播阶段;火焰传播速度呈指数增长,管道出口处压力和气流速度均呈现出先增大后减小的趋势。同时,采用高速摄影系统、压力传感器、有机玻璃管等装置对预混气体的火焰加速进程和压力演变过程进行了验证,实验结果与数值模拟结果一致。     

Synthesis of New Crystalline Pu(V) Compounds from Solutions: VI. Malonates Co(NH3)6[PuO2C3H2O4]2A · nH2O, A = HCOO, CH3COO, C2H5COO, and C3H3O4

New crystalline compounds of the general composition Co(NH₃)₆[PuO₂L]₂A · nH₂O, where L = CH₂(COO)₂ and A = HCOO, CH₃COO, C₂H₅COO, and HL, were prepared by adding a small excess of Co(NH₃) ₆ ³⁺ ions to freshly prepared neutral Pu(V) malonate solutions containing single-charged organic anions. The complexes are sparingly soluble in water and fairly stable when stored in air; they have a similar structure. Previously unknown double Np(V) malonates Co(NH₃)₆[NpO₂L]₂A · nH₂O, where A = HCOO, CH₃COO, and C₂H₅COO, isostructural with the corresponding Pu(V) compounds, were also prepared. The IR spectra of the new compounds were measured, and their behavior at heating was examined. __________ Translated from Radiokhimiya, Vol. 47, No. 5, 2005, pp. 423–426. Original Russian Text Copyright ? 2005 by Krot, Bessonov, Charushnikova, Grigor'ev, Makarenkov     

掺Er3+的20PbF2-20GaF3-15InF3-20CdF2-15ZnF2-10SnF2玻璃系统的上转换发光性质研究

制备了掺Er3+的20PbF2-20GaF3-15InF3-20CdF2-1 5ZnF2-10SnF2玻璃系统,研究了Er3+离子含量的变化对玻璃上转换发光性能的影响,探讨了761nm激发下玻璃上转换发光的机理.结果表明,在761nm激发下,可以观察到很强的408nm紫色荧光,并且同时观察到了545nm和523nm的绿色荧光.为掺稀土重金属氟化物玻璃应用于短波长上转换激光器提供了依据.     

Study of the solid-liquid equilibria in the LiPO3-Y(PO3)3 binary system

The LiPO₃-Y(PO₃)₃ system has been studied for the first time. Microdifferential thermal analysis (μ-DTA), infrared spectroscopy (IR) and X-ray diffraction were used to investigate the liquidus and solidus relations. The only new compound observed within this system is LiY(PO₃)₄, melting incongruently at 1104 K. An eutectic appears at 4±1 mol% Y(PO₃)₃ at 933 K. LiY(PO₃)₄ crystallizes in the monoclinic system C_2/c with a unit cell: a=16.201(4) Å, b=7.013(2) Å, c=9.573(2) Å, β=125.589(9)°, Z=4 and V=884.5 Å³, which is isostructural to LiNd(PO₃)₄. The infrared absorption spectrum indicates that this salt is a chain polyphosphate.     

Tetragonal-(Zr,Co)O2 solid solution: Combustion synthesis, thermal stability in air and reduction in H2, H2-CH4 and H2-C2H4 atmospheres

The synthesis of Co²⁺-stabilized zirconia by the nitrate/urea combustion route is investigated. Using seven times the so-called stoichiometric urea proportion allows to obtain for the first time the Zr_0.9Co_0.1O_1.9 solid solution fully stabilized in tetragonal form. The thermal stability in air and the reduction in H₂, H₂-CH₄ and H₂-C₂H₄ atmospheres are studied. The carbon forms obtained upon reduction are investigated. Reduction in H₂-CH₄ produces many carbon species including short carbon nanofibers, nanoribbons, hollow particles often forming bamboo structures, carbon-encapsulated Co particles and carbon nanotubes. Reduction in H₂-C₂H₄ produces 15-30 nm nanofibers.     

Structural characterization and AC conductivity of bis tetrapropylammonium hexachlorado-dicadmate, [N(C3H7)4]2Cd2Cl6

Synthesis, crystal structure, vibrational study, ¹³C, ¹¹¹Cd CP-MAS-NMR analysis and electrical properties of the compound [N(C₃H₇)₄]₂Cd₂Cl₆, are reported. The latter crystallizes in the triclinic system (space group , Z = 2) with the following unit cell dimensions: a = 9.530(1) Å, b = 11.744(1) Å, c = 17.433(1) Å, α = 79.31(1)°, β = 84.00(1)° and γ = 80.32(1)°. Besides, its structure was solved using 6445 independent reflections down to R = 0.037. The atomic arrangement can be described by alternating organic and inorganic layers parallel to the plan, made up of tetrapropylammonium groups and Cd₂Cl₆ dimers, respectively. In crystal structure, the inorganic layer, built up by Cd₂Cl₆ dimers, is connected to the organic ones through van der Waals interaction in order to build cation-anion-cation cohesion. Impedance spectroscopy study, reported in the sample, reveals that the conduction in the material is due to a hopping process. The temperature and frequency dependence of dielectric constants of the single crystal sample has been investigated to determine some related parameters to the dielectric relaxation.     

The influence of sucrose on the crystallization behaviour in the system CaO-SiO2-C12H22O11-H2O under hydrothermal conditions

Hydrothermal synthesis in the presence of sucrose has been carried out at 200 °C and autogeneous pressure in the system CaO-SiO₂-C₁₂H₂₂O₁₁-H₂O to investigate the influence of C₁₂H₂₂O₁₁ on phase formation and the crystal habit of calcium silicate hydrates (CSH-phases). A sucrose/lime ratio of 0.5 was utilized in all experiments and the reactivity of the SiO₂ source was varied using educts of different grain size of ∼40 mesh and >230 mesh. CaO/SiO₂ concentration ratios of 0.5 and 0.8 have been selected, the latter with respect to the composition of the important CSH-phase 11 Å tobermorite. The results were compared with experiments under similar but sucrose-free conditions. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX-analysis) as well as Fourier transform infrared spectroscopy (FTIR-spectroscopy) have been applied for analyses.A retarding effect of sucrose on CSH-phase formation has been observed. Only minor amount of CSH without regular morphology was observed instead of typically fibrous 11 Å tobermorite formed in the sucrose-free system. Sucrose altered the reaction mechanism in the CSH-system and hydrothermal process started with rapid reaction of sucrose and lime. The further course of crystallization was dominated by an extended precipitation of calcium carbonate and small amounts of calcium oxalate hydrate. Formation of these stable hydrothermal decomposition products of saccharated lime is strongly suppressing the CSH-crystallization.     

Hydrothermal phase equilibria in Ln2O3-H2O-CO2 systems for Tm,Yb and Lu

Phase diagrams for Tm₂O₃-H₂O-CO₂. Yb₂O₃-H₂O-CO₂ and Lu₂O₃-H₂O-CO₂ systems at 650 and 1300 bars have been investigated in the temperature range of 100–800°C. The phase diagrams are far more complex than those for the lighter lanthanides. The stable phases are Ln(OH)₃, Ln₂(CO₃)₃.3H₂O (tengerite phase), orthorhombic-LnOHCO₃, hexagonal-Ln₂O₂CO₃. LnOOH and cubic-Ln₂O₃. Ln(OH)₃ is stable only at very low partial pressures of CO₂. Additional phases stabilised are Ln₂O(OH)₂CO₃and Ln₆(OH)₄(CO₃)₇ which are absent in lighter lanthanide systems. Other phases, isolated in the presence of minor alkali impurities, are Ln₆O₂(OH)₈(CO₃)₃. Ln₄(OH)₆(CO₃)₃ and Ln₁₂O₇(OH)₁₀,(CO₃)₆. The chemical equilibria prevailing in these hydrothermal systems may be best explained on the basis of the four-fold classification of lanthanides.     

Crystal Structure of (H3O)2[(UO2)2(SeO4)3(H2O)2](H2O)3.5

Crystals of (H₃O)₂[(UO₂)₂(SeO₄)₃(H₂O)₂](H₂O)_3.5 were prepared from aqueous solutions by evaporation. The crystal structure [monoclinic system, space group P2₁/m, a = 11.9402(11), b = 13.6452(14), c = 13.7271(12) Å, β = 109.436(7)°, V = 2109.1(3) ų] was solved by the direct method and refined to R ₁ = 0. 048 (wR ₂ = 0. 082) for 3677 reflections with |F _hkl |F _hkl |. The structure consists of [(UO₂)₂(SeO₄)₃(H₂O)₂]₂₋ layers arranged parallel to the (010) plane. The layers are formed by uranium and selenium coordination polyhedra sharing common vertices and are linked with each other by hydrogen bonds through the H₂O and H₃O⁺ groups arranged between the layers. __________ Translated from Radiokhimiya, Vol. 47, No. 5, 2005, pp. 412–414. Original Russian Text Copyright ? 2005 by Krivovichev, Kahlenberg.     

Evidence for the non-existence of a bragg reflection superlattice in K2Pt(CN)4Br0.3·3H2O and K2Pt(CN)4Cl0.3·3H2O

An extensive and careful search for superlattice reflections in K₂Pt(CN)₄Br_0.3·3H₂O and K₂Pt(CN)₄Cl_0.3·3H₂O has yielded no evidence for an enlarged cell. Six individual crystals obtained via different preparative methods, from solutions at several pH values from 2 to 10, and subjected to a variety of conditions of temperature and humidity have been examined. All samples gave identical cells and nearly identical diffraction patterns. Two samples gave a single weak non-integral 00l neutron reflection which is not explainable by order contamination or double diffraction.     

Formation of nanoparticles and nanorods in a N2-C2H4-H2 atmospheric pressure dielectric barrier Townsend discharge

In the present publication, the effect of the addition of H₂ in an atmospheric pressure Townsend Dielectric Barrier Discharge in an atmosphere of N₂-C₂H₄ is examined with an emphasis put on the evaluation of the surface chemistry and growth mechanisms. Scanning Electron Microscopy, Atomic Force Microscopy, X-Ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy were used to characterize the coatings. For all H₂ concentrations, films obtained present high N/C ratio (∼ 0.8) with high NH_x and nitrile content. However, when H₂ is added in the discharge, nanoparticles/nanorods are formed imbedded in a smooth film. The average size of the nanorods is 100-200 nm in diameter with length from 1 to 10 μm. A growth mechanism is proposed to explain the formation of the nanorods on the surface of the coating in the presence of H₂.     

Crystal structures, thermal analysis and IR investigations of (C4H14N2O)SO4 and (C4H14N2O)SO4·H2O

Crystals of 2(2-ammonium ethyl ammonium)ethanol sulfate monohydrate: (C₄H₁₄N₂O)SO₄·H₂O abbreviated as AEESM, and 2(2-ammonium ethyl ammonium)ethanol sulfate: (C₄H₁₄N₂O)SO₄ abbreviated as AEES, have been prepared and grown at room temperature. These materials have the following unit cell dimensions (C₄H₁₄N₂O)SO₄·H₂O: a = 16.116(6), b = 7.411(3), and c = 15.750(6) Å; (C₄H₁₄N₂O)SO₄: a = 8.1142(2), b = 10.6632(4), c = 9.9951(4) Å, and β = 99.433(3)°. Their space groups are Pbca and P2₁/c, respectively. The structures of these compounds have been determined by single-crystal X-ray data analysis. The AEESM structure is built up from infinite inorganic chains parallel to the b axis linked via Ow-H?O hydrogen bonds. These chains are interconnected by organic groups so as to build layers perpendicular to the c direction. The structure of AEES consists of a three-dimensional network of H-bonds connecting all its components. In the present work the crystal structures, thermal behavior and IR analysis of these two new compounds are described.     

Low-temperature syntheses in the system K2OAl2O3GeO2H2O

Four crystalline phases have been synthesized in the system K₂OAl₂O₃GeO₂H₂O from over 250 runs carried out at 90, 150 and 225°C: KH₃Ge₂O₆ (GC), KAlGeO₄ (GL), an unidentified phase, GM, and GH, the germanic analogue of phillipsite. No additional phase has been obtained from mixed KNa gels. Partial results on the effect of the initial water content on the crystallization are given.     

Hydrothermal Crystallization in the Systems La2(CO3)3 ? 6H2O-CaCO3(BaCO3)-R-H2O (R = Na2CO3, K2CO3, NaHCO3, KHCO3, NaCl, NH4Cl, CO(NH2)2)

Crystallization in the systems La₂(CO₃)₃ ⋅ 6H₂O-CaCO₃(BaCO₃)-R-H₂O (R = Na₂CO₃, K₂CO₃, NaHCO₃, KHCO₃, NaCl, NH₄Cl, CO(NH₂)₂) was studied under hydrothermal conditions (400–450°C). The solid reaction products were found to contain LaOHCO₃ and NaLa(CO₃)₂. Detailed thermal decomposition schemes were proposed for these phases, and their lattice parameters were refined. __________ Translated from Neorganicheskie Materialy, Vol. 41, No. 11, 2005, pp. 1366–1372. Original Russian Text Copyright ? 2005 by Nikol'skaya, Dem'yanets.     

Liquid-vapor equilibria in the AsCl3-HCl-H2O system

The liquid-vapor equilibria in the AsCl₃-HCl-H₂O system have been studied by a flow method at high hydrogen chloride concentrations (above 20 wt %) over the entire arsenic trichloride solubility range at temperatures from 25 to 105°C and a pressure of 1.013 MPa. The composition effects on the parameters of the liquid-vapor equilibria have been assessed, and the conditions for the most effective recovery of arsenic trichloride from hydrochloric acid solutions by distillation were established.