Electrical Conductivity and Crystal Structure of Pure and SrCO3-doped K2CO3

Electrical conductivity of pure and SrCO₃ doped potassium carbonate has been investigated in the temperature range between 350 and 800 °C. Sintered carbonate mixtures were analysed by X-ray powder diffraction techniques at room temperatures. The conductivity of SrCO₃ doped K₂CO₃ increases nearly linear up to 10 mol.% and decreases in the range between 20 and 50 mol.% continously. X-ray diffraction patterns do not show changes up to 10 mol.% SrCO₃ in the host lattice. The compound K₂Sr(CO₃)₂ was found for samples containing 15–50 mol.% SrCO₃. The lattice constants of hexagonal crystals which are isotypic with K₂Ca(CO₃)₂ are a₀ = (534 ± 1) pm and c₀ = (1352 ± 2) pm.     

Interplay between phase formation mechanisms and magnetism in the Sr2FeMoO6–δ metal‐oxide compound

Double perovskites with the structural formula A₂BB′O_6±δ, especially the strontium ferromolybdate Sr₂FeMoO_6–δ, have attracted a lot of attention due to their unique magnetic and electrical properties and a possible application in spintronic devices. However, a strict correlation between the functional characteristics of Sr₂FeMoO_6–δ and its synthesis technology has been lacking up to date. Thus, we have studied in the present work the crystallization kinetics of Sr₂FeMoO_6–δ using reagents with different pre‐history as well as the structural and magnetic properties of the obtained compounds. Differences in the crystallization kinetics as well as higher magnetic inhomogeneity of Sr₂FeMoO_6–δ synthesised from a mixture of MoO₃, Fe₂O₃, SrCO₃ in comparison with the compound synthesised from the SrFeO_2.5 and SrMoO_4–y precursors have been found and interpreted. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hierarchical strontium carbonate submicron spheres self‐assembled under hydrothermal conditions

Uniform hierarchical strontium carbonate (SrCO₃) submicron spheres bearing detectable cavities on the surfaces and porous structures within the body were efficiently obtained, by a facile hydrothermal treatment (190 °C, 12 h) of the room temperature precipitate derived from Na₂CO₃ and SrCl₂ solution. MgCl₂ and ethylene diamine tetraacetic acid (EDTA) disodium salt were used as the additives. The as‐obtained submicron spheres were self‐assembled by crystalline SrCO₃nanoparticles under hydrothermal conditions. The present hydrothermally synthesized hierarchical SrCO₃ submicron spheres would enlarge the potentials of SrCO₃ micro‐/nanostructures in the hierarchical architectures and porous materials family for further applications in the fields of catalysis, composites, adsorbents, and devices, etc. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interactions between YBa2Cu3O7-x and K2Co3

The interactions between YBa₂Cu₃O_7-x and K₂CO₃ have been studied using thermochemical methods, isothermal annealing of diffusion pairs, optical microscopy, X-ray diffraction, and microprobe analyses. The experiments have shown existence of solubility of YBa₂Cu₃O_7-x or its constituents in both solid and liquid K₂CO₃. The barium ions are preferably dissolved in K₂CO₃, whereas potassium cations do not enter massively into the bulk of the YBa₂Cu₃O_7-x-phase. A eutectic-type phase diagram is supposed for the system K₂CO₃–YBa₂Cu₃O_7-x. The so called “green phase” Y₂BaCuO₅ and a K–Cu–O compound have been found in the contact zone at 813 °C while a “black phase” layer with nominal composition Y_1.6Cu_2.8O_5.4 has grown at 707 °C.     

The Hydrothermal Effect on Crystal Development and Electrical Conductivity of Li2CO3

Lithiumcarbonat was treated hydrothermally in the range of temperature from 80 °C to 600 °C. The Li₂CO₃-crystals of the starting material were monoclinic with the unit cell a = 8.39 Å, b = 5.00 Å, c = 6.21 Å, β = 114.5° and the space group C2/c (Zemann). During the increase of temperature the habit of the Li₂CO₃-crystals changed in the ranges of higher temperatures that they could be described as pseudocubic. In parallel with this development the electrical conductivity of the crystals also changed.     

Growth,Morphology, Structure and Properties of Na3BaCl5 2H2O Crystals

Single crystals of Na₃BaCl₅ 2H₂O were obtained from saturated aqueous solutions at two different temperatures (27° C and 32° C). The crystal size increases with increasing temperature. The crystals obtained were subjected to a systematic morphological, X-ray and thermal analyses. The study of as-grown crystal morphology and surface morphology of Na₃BaCl₅ 2H₂O crystals clearly indicate the requirement of a slow rate of evaporation at temperatures 27 to 28° C, moderate supersaturation in order to obtain high quality single crystals of Na₃BaCl₅ 2H₂O. The X-ray diffraction studies give the following cell parameters for the title compound: monoclinic, P21/n, a = 8.5773(9), b = 9.5502(4), c = 5.2873(3) A, β =92.069°, V = 432.8 A³, Z = 2. The study of TGA curves indicate the occurrence of dehydration process at around 200° C and not the decomposition of the compound. Similarly, the low temperature DSC study indicates a thermal anomaly at 267 K, and the high temperature DSC study (323 K to 873 K) indicates the transition from dihydrate to monohydrate and in turn anhydrous state at 454.6 K for Na₃BaCl₅ 2H₂O crystals. Thus both the TGA and DSC curves conclude that the Na₃BaCl₅ 2H₂O crystals contain two molecules of water of crystallization and its molecular formula is Na₃BaCl₅ 2H₂O.     

Crystal structure investigation of [Mn(3-CH3C5H4N)2(N3)2(H2O)2]

The crystal structure of the title compound has been determined by single crystal X-ray diffraction methods. [Mn(3-CH₃C₅H₄N)₂(N₃)₂(H₂O)₂] crystallizes in the space group P 1 with a = 7.444(2) Å, b = 7.691(2) Å, c = 8.926(3) Å, α = 99.82(3)°, β = 108.80(2)°, γ = 114.99(2)° and Z = 1. Least squares refinement gave a R value of R_w = 0.046 for 1414 observed reflections. The manganese atom in the title complex is octahedrally coordinated by two oxygen atoms of the water molecules and four nitrogen atoms; two N-atoms are the end atoms of azide groups and the other two nitrogen atoms belong to the 3-methylpyridine molecules. The polyhedra are linked via hydrogen bonds between the water molecules and the azide groups.     

Thermoanalytical and X-ray Studies of Rapidly Solidified K2CO3

Molten K₂CO₃ was rapidly solidified, and investigatcd using DSC, X-ray analysis and infrared spectra. All thermoanalytical investigations have been carried out in the temperature interval from 20 to 450 °C. The sorption of water by the anhydrous potassium carbonate is the reason for appearance of K₂CO₃ · 1.5 H₂O in the specimens. The desorption processes occur in two stages usually. The enthalpics of desorption were estimated to be about 23000 J/mol. The polymorphic phase transitions of K₂CO₃ were studied and compared with literature data.     

Crystal and Molecular Structure of mer-Co(4-CH3C5H4N)3(N3)3

The crystal structure of mer-Co(4-CH₃C₅H₄N)₃(N₃)₃has been determined by single crystal X-ray methods at 300 K. The compound crystallizes in the monoclinic space group C 2/c, a = 19.087(6), b = 16.769(4), c = 15.845(4) Å, β = 119.04(2)°, V = 4434(2) ų, M_r = 464.42. Z = 8, D_x = 1.391 Mgm⁻³, F(000) = 1920, λ (MoKα) = 0.71069 Å, μ = 0.802 mm⁻¹. The cobalt(III) ions are octahedrally coordinated to three azide groups and to three 4-methyl-pyridine molecules to form isolated coordination polyhedra.     

Refinement of the crystal structures of low-rare-earth and “typical” burbankites by the Rietveld method

The crystal structures of two samples of burbankite from the Khibiny massif, namely, low-rare-earth burbankite (Na_1.82Ca_1.02Y_0.02)_2.86(Sr_2.32Ba_0.43Ca_0.17La_0.06Ce_0.02)_3.00(CO₃)₅ from pectolite metasomatites and burbankite of the characteristic composition (Na_2.22Ca_0.65Y_0.03)_2.97 × × (Sr_2.10Ba_0.33Ce_0.23Ca_0.15La_0.12Nd_0.05Pr_0.02)_3.00(CO₃)₅ from alkaline hydrothermolites, were refined by the Rietveld method. The experimental data were collected on an ADP-2 diffractometer (λCuK _α radiation, Ni-filter; 15.00° < 2θ < 155.00°; 2θ scan with steps 0.02°; the exposure time per step, 15–20 s; the number of (α₁ + α₂) reflections 556–570). All the calculations were performed using the WYRIET program (version 3.3) in the sp. gr. P6₃ mc. For low-rare-earth burbankite: a = 10.5263(1) Å, c = 6.5392(1) Å, R _P = 3.52, R _wp = 4.49, R _B = 4.10, and R _F = 4.11. For burbankite from alkaline hydrothermolites: a = 10.5313(1) Å, c = 6.4829(1) Å, R _P = 2.54, R _wp = 3.23, R _B = 3.06, and R _F = 3.44. The structures were refined using the anisotropic thermal parameters of cations.     

Synthesis and Crystal Structure of a Pure Inorganic Network Based Tetra-Sodium Capped Sandwich-Type Polyanion

Abstract  

The synthesis and single-crystal structure of a Na-salt compound Na₁₀[Co₄(OH₂)₂(AsW₉O₃₄)₂]·32H₂O (1) was reported. Compound 1 crystallizes in triclinic system, space group P−1, with the lattice parameters: a = 11.6040(10) ?, b = 12.9361(13) ?, c = 17.396(2) ?, α = 97.4120(10)°, β = 106.8590(10)°, γ = 111.867(2)° and Z = 1. Compound 1 consists of a pure inorganic network based on tetra-sodium capped sandwich-type anionic clusters [Co₄(OH₂)₂(AsW₉O₃₄)₂]¹⁰⁻ bridged through Na–OH₂ subunits. The thermogravimetric and electrochemistry measurements had also been studied.     

Second harmonic generation properties of Ca3(O3C3N3)2 ‐Sr3(O3C3N3)2 solid solutions

Solid solutions of the second harmonic generation (SHG) materials Ca₃(O₃C₃N₃)₂ (CCY) and Sr₃(O₃C₃N₃)₂ (SCY) were prepared via exothermic solid state metathesis reactions from appropriate amounts of the corresponding metal chlorides and potassium cyanate at 525 °C. The change in SHG intensity caused by the successive cation substitution is reported. Differential thermal analyses are used to explore the SCY–K(OCN) phase diagram as a medium for the growth of SCY crystals.     

Crystal and molecular structure of the chiral compound 4–(2–methylbutyloxy)phenyl–4–(2-propenyloxy)-benzoate,C21H24O4

The enantiomeric [(S)-(–)-MBP3B] and the racemic form [(±)-MBP3B] of the title compound with the formula C₃H₅O–C₆H₄–CO₂–C₆H₄–OC₅H₁₁ were studied by single crystal analysis at room temperature. (S)-(–)-MBP3B crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 7.835(3) Å, b = 11.093(6) Å, c = 44.820(3) Å and 8 molecules per unit cell. The structure was determined from 966 reflections with intensities > 3σ. The refinement with isotropic temperature factors leads to R = 0.094. The crystals of the racemic form are monoclinic, space group P2₁/a with a = 7.899(5) Å, b = 11.046(6) Å, c = 22.845(12) Å, β = 99.28(3)°, Z = 4.1236 diffractometer data (I > 3σ) were refined by least-squares methods with anisotropic temperature factors for the non-H atoms to R = 0.070. The packing arrangement for both forms shows a layer-like structure with very similar packing coefficients, k = 0.7085 for the pure enantiomer and k = 0.7014 for the racemic form.     

Growth and characteristic of Sr3Tb(BO3)3 crystal

A new borate single crystal of Sr₃Tb(BO₃)₃ with dimension Ф20×25 mm² has been grown by the Czochralski method. The grown crystal was characterized by DTA–TGA, FTIR and X-ray powder diffraction analysis. The results showed the crystal with [BO₃]^3? is congruently melting at 1351.35 °C which belongs to hexagonal structure. The hardness of Sr₃Tb(BO₃)₃ crystal is 422.5 VDH, and is equal to 5.0 moh. The thermal expansion coefficients were determined to be 2.08×10^?5/°C along (1 0 0) direction and 7.43×10^?6/°C along (0 0 1) direction and the transmission spectrum was measured in 320–1800 nm at room temperature. The magnetic properties of the single crystal were studied which showed its paramagnetism and magnetic anisotropy. The specific Faraday rotation of single crystal was measured at room temperature in 532, 633, and 1064 nm wavelength. The Verdet constants and magneto-optical figures of merit were investigated. The primary emphasis is laid to explore a new magneto-optical material, all the magneto-optical properties of Sr₃Tb(BO₃)₃ are comparing to the ones of TGG.     

X-ray diffraction analysis of (Ph2PO)2

The title compound (Ph2PO)2 is analyzed by single crystal X-ray diffraction analysis. The crystals are monoclinic, space group P2(1)/n with a = 9.5112(19) Å, b = 11.161(2) Å, c = 9.5487(19) Å, α = 90°, β = 91.65(3)°, γ = 90°, V = 1013.2(3) ų, Z = 2, F(₀₀₀) = 420, Dc = 1.319 g cm^–3, μ = 0.232 mm^?1, the final R = 0.0818, and wR = 0.2259. A total of 7954 reflections were collected, of which 1758 were independent (R_int = 0.0542). In the crystal packing diagram, intermolecular C—H···O hydrogen bonds stabilize the solid state of the title compound.     

Addition effects of bismuth oxide on Samaria-doped ceria based lithium carbonate composite electrolytes for intermediate temperature-solid oxide fuel cells

ABSTRACT

The effect of amounts (3, 5, 10, 20 wt%) of Bi₂O₃ on the sintering characteristics and porosity of Samaria-doped Ceria (SDC) based Lithium carbonate has been evaluated. The density had a maximum as high as 98.5% of theoretical density at 800°C with only 1wt%Li₂CO₃ and 3 wt%Bi₂O₃. The composite electrolytes showed high ion conductivity at evaluated temperatures. Composition and calcination temperature were found to affect the morphology and conductivity of the composite electrolytes greatly. The total conductivity closed to 3 orders of magnitude greater than pure SDC at operating temperature of 900°C and 3.5 orders of magnitude greater than pure SDC at operating temperature of 600°C. Especially, the best sample containing 3 wt% Bi₂O₃ sintered at 800°C for 2 h which had an ionic electrical conductivity of 0.17S cm^?1. According to fuel cell performance, these composite electrolytes are chemically stable, which is an attractive prospect in intermediate temperature solid oxide fuel cell applications.     

A Novel Coordination Structure of Dichromates Bonding to Copper (II): [Cu(bipy)2(Cr2O7)] · 2 H2O

Dark-green multimetal compound crystal [Cu(bipy)₂(Cr₂O₇)]· 2 H₂O was obtained from aqueous solution of Cu(NO₃)₂, K₂Cr₂O₇ and bipyridine. The crystal structure was determined by X-ray crystallography: triclinic P1 , a = 7.716(3) Å, b = 9.656(3) Å, c = 15.517(5)Å, α = 77.41(3)°, β = 81.04(3)°, γ = 82.33(3)°, Z = 2. In this compound, two chromium atoms and a copper atom are linked by two oxo bridges (Cu(II) O Cr(VI) O Cr(VI)). The copper coordination polyhedron corresponds to a five-coordinated distorted trigonal bipyramid.     

Crystallization studies by thermometric methods (II). Calorimetric determination of chrystallization kinetics of sodium sulfate and sodium carbonate decahydrates

A calorimetric method was applied for the determination of crystallization kinetics of vibrationally mixed suspensions of Na₂SO₄ · 10 H₂O and Na₂CO₃ · 10 H₂O at 25°C with supersaturations up to 0.083 and 0.119 g hydrate/g free water, resp. The characteristic dimension of crystals was 0.125–0.63 mm.     

The precipitation of aluminium hydroxocarbonates powders from aqueous solution: Precipitate compositions and precipitation mechanisms

A series of aluminium hydroxocarbonate hydrates were prepared by precipitation from aluminium nitrate solution, with five sodium hydrogen carbonate-sodium carbonate solutions of different pH, at ambient temperature. The course of precipitation was monitored by pH measurement and the final precipitate compositions were determined by chemical analysis, infra-red spectrophotometry, X-ray diffraction and thermal analysis. Precipitation generally occurred through three stages, primary precipitation of materials with low carbonate content at low pH with evolution of carbon dioxide, their dissolution to form hydroxcarbonato anions and then secondary reprecipitation of the final products at higher pH. These materials were mixtures of polyhydroxoaluminium carbonate hydrates of general composition Al_n(OH)_3n-2CO₃ · hH₂O (where n = 2, 4, 6 and h = 6–8); their CO₃ content increased with increasing pH and carbonate anion content of the precipitant solution.     

Second harmonic generation in Na3Gd2(BO3)3 crystals

Na₃Gd₂(BO₃)₃ crystals with dimensions up to 22 × 20 × 5 mm³has been grown from NaBO₂ flux by the top‐seeded solution growth (TSSG) method for the first time. Differential scanning calorimetry (DSC) result shows that Na₃Gd₂(BO₃)₃ melts incongruently. The infrared spectrum indicates that Na₃Gd₂(BO₃)₃ contains characteristic triangular [BO₃]^3– groups responsible for the nonlinear optical effect. For the as‐grown crystal, the transmittance exceeds 80% in the wavelength range of 315 nm to 2670 nm, and the UV cutoff wavelength is 207 nm. The damage threshold is 0.47 GW cm^–2 at 1064 nm. Moreover, Na₃Gd₂(BO₃)₃ crystal exhibits an optical second harmonic generation effect which is 1.3 times as large as that of KH₂PO₄ (KDP). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)