Papers by Keyword: Crystal Structure

Abstract: A compound of 9,9-dipropionitrilefluorene (C₁₉H₁₆N₂, Mr=272.34) was synthesized via nucleophilic addition reaction under microwave irradiation (500 w) within short reaction time (8 min), giving high yield of product (87%). Its structure was determined IR, ¹H NMR, MS, elemental analysis and X-ray diffraction. The crystal belongs to monoclinic, space group P2(1)/c with a = 21.8358(16),b = 8.9457(7), c = 15.9895(12) Å, β = 105.078(2)^o, V= 3015.8(4) Å3, Z=8, Dc= 1.200 g/cm3,μ=0.071 mm-1, F(000)=1152, R=0.0629 and wR = 0.0881 for 3155 observed reflection with I>2σ (I). X-ray analysis reveals that the three fused rings of the fluorene system are almost coplanar and the two propionitrile groups are completely perpendicular to the fused-ring system, the molecular is symmetrical.

Abstract: The synthesis and characterization of the magnetic materials of La0.8Ba0.2Mn (1-x)TixO3 system (x = 0 0.7) by mechanical alloying process have been performed. This magnetic material is prepared by oxides, namely La2O3, BaCO3, MnCO3 and TiO2. The mixture was milled for 10 h and then sintered at 1000 ° C for 10 h. The refinement results of x-ray diffraction pattern showed that the doping concentration (x < 0.5) was a single phase, which has a structure monoclinic (I12/a1) with lattice parameters a = 5.5169(5) Å, b = 5.5437(5) Å and c = 7.8553(7) Å, = 90o and 89.75(1) o, V = 240.25(4) Å3 and 6.345 gr.cm-3. The microstructure analysis showed that the particle shapes was polygonal with the varied particle sizes distributed homogeneously on the surface of the samples. We concluded that the maximum number of titanium atoms substituting manganese atom is around x ~ 0.43 without changing the structure of this system.

Abstract: SHS products in Cu/Sn films have been investigated. New BCC Cu/Sn phase has been found. The scheme which illustrates transition of the FCC-lattice of copper and a tin HCP-lattice to system of octahedrons of a new phase with BCC lattice has been offered

Abstract: The current work deals with experimental tests concerning the behaviour of different materials used in chemical industry when are exposed to diverse corrosions environments. During the research work four different metals have been tested, namely T₁₅NiCr₁₈₀, T₁₅MoNiCr₁₈₀, W4027 and W4059. The presented work is trying to classify the tested materials function to different chemical environment, different concentration of the environment, different temperature of the environment, and different expose time. Some of the substances which were considered as corrosion environment are: HNO₃, H₃PO₄, NaCl, NH₄Cl, C₂H₅OH, Petrol, NH₄NO₃, KNO₃, K₂CO₃, Na₂CO₃, KMnO₄, KOH and Ca (OH)₂. The concentration of the corrosion solutions varies between 1% and 96%. Tests have been done at room temperature and hot environment of 100°C. Time is playing an important role on evolution of the corrosion. For this reason the samples have been analyzed after 48, 336, 720 and 2160 hours of exposes to chemical agents. To understand the comportment of the subject metals when are used in industry, samples have been tested for longer period of time, respectively 1, 3, 6 and 12 months. After each selected period of time the metallic samples were analyzed and measured to quantify the effect of the environment on the corrosion speed.

Abstract: The coordination polymer, [Sm₂(HPyImDC)₂Ox (H₂O)₂·6H_2n [H₃PyImDC = 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid, Ox = oxalate], has been synthesized under hydrothermal conditions and characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 28.166(6), b = 6.9970(14), c = 16.655(3) Å, V = 2685.4(9) ų, Z = 4, D_c = 2.298 g/cm³, μ(MoKα) = 4.428 mm^-1, F(000) = 1852, the final R = 0.0412 and wR = 0.1010. The complex forms a three-dimensional (3D) framework structure.

Abstract: A new uranium-containing silicotungstate A-β-Na₁₄[Na₂(UO₂)₂(SiW₉O₃₄)₂]·43H₂O (1) was synthesized in an aqueous solution. The compound was characterized by elemental analysis and infrared spectra analysis. A single-crystal X-ray analysis was carried out on crystal (1) which crystallizes in triclinic system, space group p ī, with a = 13.386 Å, b = 13.506 Å, c = 16.183 Å, α = 85.337o, β = 73.608o γ = 64.833o and Z = 1. Polyanion (1) consists of two A-β-SiW₉ units which sandwich two uranium and two sodium ions, leading to a Keggin-type sandwich structure. The photoluminescent spectrum of (1) shows typical emission features of uranyl compounds.

Abstract: The Zn (II) complex [Zn (O₂CFcCO₂)(H₂O)₂]H₂O was synthesized with ferrocenedicarboxylic acid under mild conditions. Its crystal structure was characterized by elemental analysis, IR data and X-ray diffraction single crystal structure analyses. The Zn (II) coordination units are connected, forming one-dimensional chain. At the meanwhile, the luminescence properties and the electronic properties were determined.

Abstract: Two new Ce(III) coordination polymers formulated as Ce(bpdc)(Hbpdc)(DMF)2 (1) and [Ce2(bpdc)3(DMF)2(H2O)4]·2DMF (2) (H2bpdc = 2,2'-bipyridine-4,4'-dicarboxylic acid, DMF = N,N-Dimethyl formamide) have been synthesized under solvothermal condition and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic, space group C2/c with a = 2.2520(2), b = 1.17787(12), c = 1.16128(11) nm, α = 90, β = 95.5600(10), γ = 90°, V = 3.0658(5) nm3, Z = 4, Mr = 771.70, Dc = 1.672×10-9 g/cm3. Compound 2 crystallizes in triclinic, space group Pwith a = 1.00610(10), b = 1.17219(11), c = 1.36891(14) nm, α = 66.9340(10), β = 87.182(2), γ = 76.2570(10) °, V = 1.4411(2) nm3, Z = 1, Mr = 1371.25, Dc = 1.580×10-9 g/cm3. Both compounds exhibit 3D Ce(III)–organic frameworks. Furthermore, thermal stability and luminescent properties were also investigated. CCDC:(1)913670, (2)909563.

Abstract: The crystal structure of magnesium hydride affects the properties of magnesium for hydrogen storage. The crystal phase and dehydriding temperature of magnesium hydride from magnesium by high-energy ball milling under hydrogen atmosphere with anthracite carbon, which was prepared from anthracite coal by demineralization and carbonization, as milling aid was investigated. The HRTEM observation and XRD characterization showed that the Mg hydrided into nanocrystalline β-MgH₂ of tetrahedral crystal structure and γ-MgH₂ of orthorhombic crystal structure during milling under 1 MPa of hydrogen, and the γ-MgH₂ increased with the extension of milling time. The DSC analysis showed that the endothermic peak of γ-MgH₂ was 53 °C lower than that of β-MgH₂ in the material from 10 h of milling.

Abstract: Polycrystalline sample of the reduced barium titanate Ba₄Ti₁₂O₂₇ was prepared by solid state reaction in Ar atmosphere. The magnetic susceptibility was nearly temperature independent in the range of 75-300 K, suggesting the Van Vleck Paramagnetism. The temperature dependence of the electric conductivity does not obey any Arrhenius type behavior.