Conductivity of Al2(WO4)3–WO3 and Al2(WO4)3–Al2O3 Composites

Russian Journal of Electrochemistry - Composites of (1 – x)Al2(WO4)3–xWO3 and (1 – x)Al2(WO4)3–xAl2O3 are synthesized and their conductivity is studied as dependent on the...     

Raman and infrared spectra of GdTb (MoO4)3 single crystal in the region 250–1000 cm−1

Polarized Raman spectra (single crystal) at 300 K and infrared spectra (powder) at 300 and 85 K in the region 250–1000 cm⁻¹ of a binary molybdate of gadolinium and terbium have been recorded. Based on C_2ν symmetry, group theoretical analysis has been carried out and vibrational assignment is proposed. The observed symmetric stretching frequencies of the MoO²⁻₄ ion points to the absence of resonance vibrational interaction in this system.     

Investigation of nonstoichiometry and ferroelectric properties in the ternary system Li2OTa2O5(WO3)2 at 1250°C under atmospheric pressure

X-ray crystallographic studies conducted at atmospheric pressure have allowed determination of the limits of solid solutions with LiTaO₃ structure in the ternary system Li₂OTa₂O₅(WO₃)₂. Stoichiometry analysis has shown that the prevailing type of nonstoichiometry of these phases is simultaneous cationic and anionic deficits. Dielectric measurements carried out on the ceramic samples showed a decrease in the ferroelectric Curie temperature as the composition deviates from that of pure LiTaO₃.     

Yb3+:KY(WO4)2晶体生长与光谱性能

采用泡生法生长YbKYW晶体, 通过XRD分析确认所生长的晶体为β-YbKYW. TG-DTA测量结果表明, 晶体的熔点为1045 ℃, 相变温度为1010 ℃. 测得晶体红外光谱和拉曼光谱, 对其峰值所属振动的归属进行了指认, 并测量了晶体的吸收光谱和荧光光谱. 结果表明, YbKYW晶体在940, 980 nm附近有很强的吸收峰, 主峰980 nm处的吸收截面积为1.34×10-19 cm2;该晶体在990, 1010, 1030 nm附近都有较强的荧光发射峰, 其中最强发射峰1030 nm的发射线宽高达16 nm, 有望作为可调谐激光器的增益介质. 计算得其1030 nm受激发射截面积为3.1×10-20 cm2.     

The influence of medium on the stability of coordination compounds 4.The system In(tiron)~--NaClO_4-C_2H_5OH-H_2O

The stability constants of complex anion In(tiron)~-in mixed solvents of ethanol-water withweight percentages of ethanol being 0,5,15,25,35 and 50 have been measured spectrophotometricallyat 293 K,using NaClO_4 as supporting electrolyte with ionic strength ranging from 0.1 to 3.3mol·dm~(-3).The thermodynamic stability constants of In(tiron)~-in various mixed solvents have been obtained bya polynomial approximation equation based on Pitzer's theory.As a comparison,the traditionalDebye-Hückel equation has also been used to treat the same data.The results show that this polynomialapproximate method is obviously superior to the old one.It was discovered that there is a linear rela-tion between the thermodynamic stability constants of In(tiron)~-and the mole fraction of organiccomponent in mixed solvents or the reciprocal of dielectric constants of mixed solvents.The mediumeffect and the standard free energy of transfer,ΔG_(tr)~0,for the coordination reaction:In~(3+)+tiron~(4-)=In(tiron)~-,have also been discussed.     

Phase equilibria in the ternary system: MgONa2OP2O5: Partial system: Mg3(PO4)2Mg4Na(PO4)3Na4P2O7Mg2P2O7

The partial system Mg₃(PO₄)₂Mg₄Na(PO₄)₃Na₄P₂O₇Mg₂P₂O₇ in the ternary system MgONa₂OP₂O₅ was investigated using thermal and X-ray diffraction analyses and microscopy, and its phase diagram has been determined. In this range of composition, two binary phosphates occur: Mg₄Na(PO₄)₃ and Mg₆Na₈(P₂O₇)₅. The former melts incongruently (at 1155°C) and the latter does congruently (at 808°C). In the partial system of interest, the two sections Mg₄Na(PO₄)₃Mg₂P₂O₇ and Mg₄Na(PO₄)₃Mg₆Na₈(P₂O₇)₅ are studied, and their phase diagrams are established. The partial system is divided into three partial ternary systems in which two ternary eutectics and one ternary peritectic occur.     

Kinetics of decomposition of the liquid phase of the ternary system LiOH-H2O2-H2O in the presence of the solid phase of Li2O2 · H2O

The kinetics of decomposition of hydrogen peroxide in the liquid phase of the ternary system LiOH-H₂O₂-H₂O was studied in the presence the solid phase of Li₂O₂·H₂O and without it. The main kinetic parameters of the processes studied were determined.     

Investigation of phase equilibria in the Er2O3–Na2O–P2O5 system: the partial system ErPO4–NaPO3–Er(PO3)3

The partial system ErPO₄–NaPO₃–Er(PO₃)₃ of the Er₂O₃–Na₂O–P₂O₅ oxide system has been investigated by thermoanalytical methods and X-ray powder diffraction. On the basis of the obtained results the phase diagram of the partial system is proposed. The system is bounded by three subsystems: (i) ErPO₄–Er(PO₃)₃, (ii) Er(PO₃)₃–NaPO₃ and (iii) ErPO₄–NaPO₃. Their phase diagrams are proposed. In the Er(PO₃)₃–NaPO₃ subsystem an intermediate compound NaEr(PO₃)₄ occurs; it melts incongruently at 655 °C. It was found that ErPO₄ and NaEr(PO₃)₄ form a section which is a real system only in the subsolidus region (below 646 °C). Two ternary invariant points (one ternary peritectic and one ternary eutectic) occur in the investigated partial system ErPO₄–NaPO₃–Er(PO₃)₃.     

Thermal stability of In2(MoO4)3 and phase equilibria in the MoO3–In2O3 system

Thermal stability of a compound forming in a binary system MoO₃?CIn₂O₃ was investigated by DTA/TG, XRD and SEM methods in this study. For the first time, the diagram of phase equilibria established in the whole range of concentrations of this system's components has been constructed. The temperature and concentration ranges of the components of MoO₃?CIn₂O₃ system in which the compound In₂(MoO₄)₃ co-exists in solid state with MoO₃ or In₂O₃ or with the liquid were determined. The composition and melting point of the eutectic mixture consisting of In₂(MoO₄)₃ and MoO₃ were found.     

Dye laser circular dichroism and absorption of the optically active Na3(Nd( C4H4O5)3]·2NaClO4·6H2O single crystal

A cw dye laser circular dichroism (CD)/absorption apparatus is described and applied to the measurement of an optically active rare earth-organic ligand single crystal. The Nd³⁺ tris(diglycolate) complex in the NA₃ [Nd(C₄H₄O₅)₃]·2NaClO₄·6H₂O crystal has been investigated from 12 to 300 K. Absorption spectra at 300 K reveal hot bands from whose positions the crystalfield-split components of the ⁴I_9/2 ground state are deduced. These values are confirmed from the temperature dependence of the peak intensity of the 17184 cm⁻¹ circular dichroism band. The ''⁴I_9/2 state crystal field components are at 0, 20, 200, 320 and 450 cm⁻¹. A weak electron-phonon coupling exists between the Nd³⁺ ion and the crystal lattice modes.     

Studies of the rhenium oxygen bond—V. The vibrational spectra and force constant analysis of K3ReO2(CN)4, K2ReO2(13CN)4 and K3Re18O16O(CN)4 and some comments on the vibrational spectra of Re2O3(CN)84−

The i.r. spectra (4000-50cm⁻¹) and laser Raman spectra of solid K₃ReO₂(CN)₄, K₃ReO₂(¹³CN)₄ (99% ¹³C enriched), and K₃Re¹⁸O¹⁶O(CN)₄ (20% ¹⁸O enriched) have been measured. An assignment of the vibrational frequencies for the D_4h ion has been made. A normal coordinate analysis was carried out. The refined force constants, and potential energy distributions are tabulated. A symmetry factoring treatment of Re-O force constants has also been shown to be valid for the ReO₂(CN)³⁻₄ ion, and has been used for the Re₂O₃(CN)⁴⁻₈ ion.     

Synthesis of Sb(VO3)3 and study of ternary system xNH4VO3?+?(1???x)(NH4)2HPO4?+?Sb2O3

Sb(VO₃)₃ has been synthesized by interaction between NH₄VO₃ and Sb₂O_3. The compound crystallizes in monoclinic system with lattice parameters: a = 17.150; b = 15.940; c = 14.600 Å and angle ?? = 90.50°. The scanning electronic microscopy shows thin flat plates measuring ~20 ??m along with detritus material. The synthesis was simulated by thermal analysis and the final product identified by X-ray diffraction. Thermal analyses of the ternary system xNH₄VO₃ + (1 ? x)(NH₄)₂HPO₄ + Sb₂O₃ lead to the formation of Sb(VO₃)₃ and SbPO₄ at 500 °C. At high temperature (900 °C), SbVO₄, SbOPO₄, VO and SbP₅O₁₄ are formed. The data of thermal analysis match with the composition of intermediate and final products. No solid solutions containing simultaneously PO ₄ ^?3 and VO ₄ ^?3 ions have been found.     

The molecular and crystal structure of N-(4-n-butyloxybenzylidene)-4′-ethylaniline (4O.2) and N-(4-n-heptyloxybenzylidene)-4′-hexylaniline (7O.6)

Abstract

The molecular and crystal structure of N-(4-n-butyloxybenzylidene)-4′-ethylaniline (4O.2) and the homologue N-(4-n-heptyloxybenzylidene)-4′-hexylaniline (7O.6) have been solved (at room temperature) by direct methods. The crystals of both compounds belong to the triclinic system with space group P1 with two molecules per unit cell. 4O.2: a = 5·531(2), b = 7·592(3), c = 19·746(7) Å, α = 86·66(2), β = 88·15(2), γ = 90·29(2)° 7O.6: a = 5·420(2), b = 8·307(3), c = 28·057(7) Å, α = 91·69(2), β = 89·76(2), γ = 108·02(2)°. The structures were refined by full-matrix least-squares calculations to R = 0·036 for 2297 observed reflections for 4O.2 and to R = 0·037 for 2150 reflections for 7O.6. The conformations in the asymmetric units of the two compounds differ considerably: The planes of the two phenyl rings of 4O.2, forming the mesogenic core of the molecule, are twisted at 61·2° to each other and the butoxy group contains a gauche conformation. In contrast the heptoxy chain of 7O.6 forms an all trans-conformation which lies almost in one plane with the two coplanar phenyl rings. The hexyl group also exists in an extended form, in a plane which is rotated against the plane of the mesogenic unit. The packing in the crystalline state of the two homologues exhibits a layered structure along c*; in 4O.2 these layers are separated, but in 7O.6 they are interdigitated. The compensation of the dipole moments of the C?O?C and C?N?C bonds occurs similarly in both structures: molecular orientations parallel to the a, c-plane in which the long axes of the molecules points in the same direction are packed in antiparallel fashion along b*.     

An investigation of the polythermal diagram of the H2ONa2HPO4Na2SO4 system

The polythermal diagram of the ternary system H₂ONa₂HPO₄Na₂SO₄ has been established, setting up nine isotherms obtained between 0 and 25°C by conductimetric analysis. The solubility domains of the various solid phases have been determined. One eutectic, three stable and one metastable transitional transformations have been observed. Temperature and composition of the eutectic point have been obtained by thermal analysis at constant flow.     

Formation and structure of a Pd(I) complex: The crystal structure of (C5H8N2S)4Pd(II)Cl2·H2O and the ESR study of the X-irradiated single crystal

The crystal structure of tetrakis(tetrahydro-1H-pyrimidine-2-thione)palladium(II) dichloride monohydrate has been determined. X-irradiation of a single crystal, at liquid-nitrogen temperature, leads to formation of a paramagnetic species whose ESR study has been performed at 77 K. The g and ¹⁰⁵Pd-hyperfine tensors have been obtained. Their eigenvalues are consistent with the trapping of a d⁹ ion. Comparison of the eigenvectors with the crystallographic bond directions shows that the paramagnetic species results from the reduction of Pd(II) to Pd(I) which remains at the center of a square formed by four sulphur atoms.