High-pressure effect on inverse spinel LiCuVO_4:X-ray diffraction and Raman scattering

The effect of external quasi-hydrostatic pressure on the inverse spinel structure of LiCuVO4 was studied in this paper. High-pressure synchrotron X-ray diffraction and Raman spectroscopy measurements were carried out at room temperature up to 35.7 and 40.3 GPa, respectively. At a pressure of about 20 GPa, both Raman spectra and X-ray diffraction results indicate that LiCuVO4 was transformed into a monoclinic phase, which remained stable up to at least 35.7 GPa. Upon release of pressure, the high-pressure phase returned to the initial phase. The pressure dependence of the volume of low pressure orthorhombic phase and high-pressure monoclinic phase were described by a second-order Birch-Murnaghan equation of state, which yielded bulk modulus values of B0 = 197 （5） and 232（8） GPa, respectively. The results support the empirical suggestion that the oxide spinels have similar bulk modulus around 200 GPa.

Powder x-ray diffraction and Rietveld analysis of (C_(2)H_(5)NH_(3))_(2)CuCl_(4)

Structural properties of the organic-inorganic hybrid(C_(2)H_(5)NH_(3))_(2)CuCl_(4) have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 occurs at T_(4)= 240 K, which results in a paraelectric–ferroelectric phase transition. The release of the Jahn–Teller distortion with increasing temperature toward T_(4) is revealed by the structural analysis.

X-ray Powder Diffraction Pattern of Bi_4(SiO_4)_3

In cooperation with figure-of-merits the Rietveld analysis can appraise both angular and intensity data of powder diffraction. In this work, X-ray diffraction pattern of Bi4(SiO4)3 was redetermined with intensity figure-of-merits, which qualify agreement between observed and calculated relative intensities. F30 is 158.90 (0.0059, 32), intensity figure of merit Rint is 8.7, I20(17), 8.0. The values of figure-of-merits show that the data of JCPDS cards are distorted. Both the experimental and calculated peak positions and heights are listed in detail.

Study of Oxidation Kinetics in Air of Zircaloy-4 by <i>in Situ</i>X-Ray Diffraction

The zircaloy-4 is an alloy of zirconium, which has a very weak thermal neutron absorption, satisfactory mechanical properties and good corrosion resistance at high temperature. For these reasons, zircaloy-4 is used as a material of cladding fuel rod of nuclear reactors. In this environment, it is submitted to different severe conditions of temperature and pressure. The objective of this work is to study the oxidation kinetics of zircaloy-4 in air by the X-ray diffraction technique. The experiments were realized in a “HTK1200” furnace installed as a sample holder in the diffractometer at different temperatures;25°C, 350°C, 500°C, 830°C and 1000°C. The results show that the monoclinic and the tetragonal phases are formed at 350°C temperature. The volume fraction of these phases increased with the temperature until 1000°C where the α phase disappears completely. For simulating the case of loss-of-coolant-accident (LOCA), we have done x-ray diffraction of Zry-4 samples water quenched at 1050°C with different ageing times at this temperature. At 10 seconds and more, there is an important evolution of monoclinic and tetragonal zirconias, which leads to the degradation of zircaloy-4 properties.

Properties and characterization of 1-methy-4,5-dinitroimidazole

X-ray diffraction （XRD）, differential scanning calorimeter （DSC） and impact sensitivity instrument were used to characterize the properties of 1-Methyl-4, 5-dinitroimidazole （MDNI）. Furthermore, specific heat capacity, thermal kinetic parameters, thermal decomposition reaction rate constant, critical explosion temperature and the drop height for impact initiation of MDNI were calculated and analyzed. The results show that MDNI is well-crystallized. The melting point of MDNI is about 74 ℃, and the specific heat capacity of MDNI is 9. 314 4 J/（g · K） and 10. 596 0 J/（g · K） when the temperature is 60 ℃ and 90 ℃, respectively. The apparent activation energy and pre-exponential factor of MDNI are calculated as 81.62 kJ/mol and 6. 78×10^7 s^-1 , respectively. The relationship between thermal decomposition reaction rate constant of MDNI and temperature is logk=7.83-4268.11/T. The critical temperature of MDNI thermal explosion is 234. 86℃. The drop height for impact initiation of MDNI is 95.3 cm.

Corrosion Behaviours of Copper Alloy in Solutions Containing Na_2SO_4 and NaCl with Different Concentrations

Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCI, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCI shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.

Synthesis and Crystal Structure of(Z)-2-Methyl-5,6-dihydrobenzo[d]thiazol-7(4H)-one O-Prop-2-yn-1-yl Oxime Derivatives

Compound（Z）-2-methyl-5,6-dihydrobenzo[d]thiazol-7（4H）-one O-prop-2-yn-1-yl oxime, C11H12N2 OS, as a synthetic precursor of cytotoxic triazoles has been prepared and characterized by NMR spectra. Meanwhile, the crystal of IV was obtained and determined by X-ray single-crystal diffraction. Crystal data： monoclinic system, space group P21/c, a = 9.725（9）, b = 8.068（7）, c = 14.452（13）A, β = 98.68（2）°, V = 1120.9（17）A3, Z = 4, F（000） = 464, Dc = 1.305 g/cm^3, μ = 0.263 mm^-1, R = 0.0457 and w R = 0.1298 for 11511 independent reflections（Rint = 0.0709） and 2289 observed ones（I 〉 2σ（I））.

Synthesis,spectroscopic characterization and thermal studies of some lanthanide(Ⅲ) nitrate complexes with a hydrazo derivative of 4-aminoantipyrine

A heterocyclic ligand synthesized by the coupling of diazotized 4-aminoantipyrine with acetylacetone reacted with lanthanide(Ⅲ) nitrate to form complexes of the type [Ln(HAAP)2(NOз)з] where, Ln=La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), or Gd(Ⅲ) and HAAP=3-{[2-(N-1-phenyl-2,3-dimethylpyrazol-3-in-5-on-4-yl)]hydrazone}pent-2,3,4-trione. The ligand and metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, UV-Visible, infrared, far infrared and proton NMR spectral data. The spectral data revealed that the ligand existed in the hydrazo form and coordinated to the metal ion without deprotonation in a neutral tridentate manner, through carbonyl oxygen of pyrazolone ring, hydrazo nitrogen and carbonyl oxygen of the acetylace-tone moiety. The molar conductance values adequately supported their non-electrolytic nature. The ligand and the praseodymium(Ⅲ) complex were subjected to X-ray diffraction studies. Thermal decomposition behavior of the lanthanum(Ⅲ) complex was also examined.

Synthesis and Electrochemical Behavior of Electroactive Bistetrathiafulvalene-attached Thiacalix[4]arene Assemblies

Tetrabromoalkylthiacalix[4]arenes（1a and 1b） reacted with excess bis（tetraethylammonium）-bis（1,3- dithiole-2-thione-4,5-dithiol）zincate（2） to give thiacalix[4]arene-thiones（3a and 3b） in the presence of Na2S. Two novel bistetrathiafulvalene-attached thiacalix[4]arene assemblies（5a and 5b） formed via triethyl phosphite-mediated cross-coupling of thiacalix[4]arene-thiones（3a and 3b） and 4,5-biscyanoethylthio-1,3-dithiole-2-one（4）. All the four new compounds were characterized by 1H NMR, 13C NMR, IR, MS spectra and elemental analysis. Meanwhile, the structures of thiacalix[4]arene-thiones（3a and 3b） were identified by X-ray analysis. In addition, the cyclic voltammograms of the resulting thiacalix[4]arenes containing electroactive TTF units（5a and 5b） were provided.

Calculating Hamiltonian parameters for Yb^(3+) in a low-symmetry lattice site,and fitting the structure and levels of Yb^(3+) :TaO_4 (= Gd,Y,and Sc)

An iterative method is used to find the values of the Hamiltonian parameters for Yb^3＋ in a given low-symmetry crys- talline site. Samples of Yb^3＋ ：RETaO4 （RE = Gd, Y, and Sc） were prepared and their structures were determined. Based on the obtained structural data, their orbital-spin parameters and crystal field parameters were fitted by the superposition model （SM）. Using the crystal field parameters obtained by the SM fitting as the initial parameters, the Hamiltonian parameters were fitted iteratively. The calculated and experimental energy levels for Yb^3＋：RETaO4 are consistent, and the maximal mean-root-square deviation is only 2.84 cm^- 1, indicating that the method is effective to determine the Hamiltonian parameters of Yb^3＋ in low-symmetry crystalline sites.

Synthesis and Crystal Structure of Picrates of 3,5-Diamino-1,2,4-triazole

The title compound C2N5H6＋C6N3O7H2-was synthesized by the reaction of 3,5-diamino-1,2,4-triazole and picric acid in the mixture of ethanol and water solution.Single crystals suitable for X-ray measurement were obtained at room temperature.The structure was characterized by elemental analysis and IR and determined by X-ray diffraction analysis.Crystallographic data：C8N8H8O7,Mr = 328.22,monoclinic,space group C2/c with a = 22.815（2）,b = 4.8086（5）,c = 22.564（2）,β = 93.976（2）°,V = 2469.6（4）3,Dc = 1.766 g/cm3,Z = 8,μ = 0.156 mm-1,F（000） = 1344,the final R= 0.0309,wR= 0.0864.

Compression behavior and phase transition of β-Si_3N_4 under high pressure

The compressibility and pressure-induced phase transition of β-Si3N4 were investigated by using an angle dispersive x-ray diffraction technique in a diamond anvil cell at room temperature. Rietveld refinements of the x-ray powder diffraction data verified that the hexagonal structure（with space group P63/m, Z = 2 formulas per unit cell） β-Si3N4 remained stable under high pressure up to 37 GPa. Upon increasing pressure, β-Si3 N4 transformed to δ-Si3N4 at about 41 GPa. The initial β-Si3N4 was recovered as the pressure was released to ambient pressure, implying that the observed pressureinduced phase transformation was reversible. The pressure–volume data of β-Si3N4 was fitted by the third-order Birch–Murnaghan equation of state, which yielded a bulk modulus K0= 273（2） GPa with its pressure derivative K0= 4（fixed）and K0= 278（2） GPa with K 0= 5. Furthermore, the compressibility of the unit cell axes（a and c-axes） for the β-Si3N4 demonstrated an anisotropic property with increasing pressure.

Spontaneous volume magnetostriction of Dy_2AlFe_(12)Mn_4 compound

The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Dy2AlFe12Mn4 compound from 229 to 280 K by X-ray dilatometry. The coefficient of the average thermal expansion is α^- =-3.8×10^-5 K^-1. The magnetostrictive deformations from 105 to 270 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 6.2 × 10^-3 to near zero with the temperature increasing from 105 to 270 K, the spontaneous linear magnetostrictive deformation λc along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane at the same temperature except close to 249 K.

Synthesis,Crystal Structure and Cytotoxic Activities of 1-(Prop-2-yn-1-yl)-7,8-dihydro-1H-benzo[d][1,3]-thiazine-2,5(4H,6H)-dione Derivatives

The important synthetic precursor（Ⅲ）, 1-（prop-2-yn-1-yl）-7,8-dihydro-1Hbenzo[d][1,3]thiazine-2,5（4H,6H）-dione（C（11）H（11）NO2S）, was prepared through a three-component reaction, which was further transferred into cytotoxic triazoles by alkylation and ＂click＂ synthesis in satisfactory yields of 87%^95%. Their structures were characterized by IR, H-RESI-MS and NMR analysis. Meanwhile, the crystal of Ⅲ was obtained and determined by X-ray single-crystal diffraction. Crystal data： orthorhombic system, space group P212121, a = 5.189（4）, b = 8.661（6）, c = 23.498（17） A, V = 1056.2（13） A^3, Z = 4, F（000） = 464, Dc = 1.392 g/cm^3, μ =0.284 mm^-1, R = 0.0637 and wR = 0.1668 for 8182 independent reflections（R（int） = 0.1580） and 2166 observed ones（I 〉 2σ（I））.

Synthesis and Crystal Structure of 4-(4,6-dimethoxyl -pyrimidin-2-yl)-3-thiourea Carboxylic Acid Methyl Ester

The title compound 4-（4,6-dimethoxylpyrimidin-2-yl）-3-thiourea carboxylic acid methyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at the room temperature. The structure was characterized by elemental analysis and IR and determined by X-ray diffraction analysis＇ Crystallographic data： C9H12N4O4S, Mr = 272.29, monoclinic, space group C2/m with a = 1.6672（3）, b = 0.66383（12）, c = 1.1617（2） nm, β = 109.275（2）°, V = 1.2136（4） nm^3, Dc = 1.490 g/cm^3,μ = 0.281 mm^-1, F（000） = 568, Z = 4, R1 = 0.0341and wR2 = 0.1042.

Synthesis and Crystal Structure of 2-(1-Naphthalenylamino)-4-thiazolidinone

The compound 2-（1-naphthalenylamino）-4-thiazolidinone was synthesized by the reaction of 1-（naphthalene-1-yl）thiourea with ethyl chloroacetate in an ionic liquid, and its structure was characterized by IR, 1H NMR and single-crystal X-ray diffraction. The crystal of the title compound belongs to monoclinic, space group P21 /c with a=10.0081（3）, b=14.5312（4）, c=7.8739（2） , β=99.425（3）°, Z=4, V=1129.64（5）3 , Dc=1.425 g/cm3 , μ=0.269 mm-1 , F（000）=504, the final R=0.0519 and wR=0.1507. X-ray analysis indicated that the five-membered ring is essentially planar in this molecule, and intermolecular hydrogen bonds N（1）-H（1）…N（2）, C（3）-H（3）…O（1）, C（4）-H（4）…O（1） and C（12）-H（12a）…O（1） were observed. π-π Stacking interactions contribute to the stability of the structure. DSC-TG analysis showed that the title compound experienced a phase change at 190 ℃ and began to decompose above 240 ℃.

First-order character of the displacive structural transition in BaWO_4

Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode （RUM） provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in SaWO4： a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO4, which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaOs polyhedrons to the small displacive distortion of rigid WO4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds.

Synthesis of TiN/a-Si_3N_4 thin film by using a Mather type dense plasma focus system

A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM）. The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness （root-mean-square）.

Synthesis and Characterization of a New Barium Aluminoborate, Ba2Al4B6O17

A new barium aluminoborate, Ba2Al4B6O17, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601(5), b = 9.1835(6), c = 10.6574(7) ?, a = 95.050(6)°, b = 111.569(5)°, g = 90.280(6)°, V = 811.71(9) ?3, Z = 2, Mr = 719.46, Dc = 2.944 g/cm3, μ = 5.127 mm-1, F(000) = 660, R = 0.0361 and wR = 0.0855 for 3846 observed reflections and 262 variables. This compound represents a new structure that features a three-dimensional [Al4B6O17]n4n- framework constructed by AlO4 tetrahedra, BO3 triangles, and B2O54-groups composed of two corner-sharing BO3 triangles, with intersecting open channels accommodating Ba2+ cations. It melts incongruently at 849 ℃. The existence of BO3 groups is confirmed by FT-IR and Raman spectra. The insulating nature with an optical band gap of about 3.50 eV is revealed by UV-VIS diffuse reflectance spectrum. Band structure calculations indicate that it is an indirect band material.

Synthesis, Crystal Structure and Antiproliferative Activity of 2-(((5-(((5,7-Dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidin-2-yl)thio)methyl)-4-phenyl-4H-1,2,4-triazol-3-yl)thio)methyl)-4Hchromen-4-one Methanol Solvate

The novel crystal of the title compound 2-（（（5-（（（5,7-dimethyl-[1,2,4]triazolo-[1, 5-a]-pyrimidin-2-yl）thio）methyl）-4-phenyl-4H-1,2,4-triazol-3-yl）thio）methyl）-4H-chromen-4-one methanol solvate（C27H25N7O3S2, Mr = 559.66） has been prepared and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to the monocline system, space group P21/c with a = 11.9879（9）, b = 14.0743（10）, c = 15.9706（11）A, β = 98.509（2）°, V = 2664.9（3）A3, Z = 4, Dc = 1.395 g/cm^3, F（000） = 1168, μ = 0.116 mm-1, MoKa radiation（λ = 0.71073）, R = 0.0652, and wR = 0.1425 for 5220 observed reflections with I 〉 2σ（I）. X-ray diffraction analyses reveal that the molecule adopts a C-shape. The planes of the benzopyrone and triazolopyrimidine were nearly parallel to each other, with a dihedral angle of 1.21（3）°. Intramolecular and intermolecular hydrogen bonds together with π-π interations are found to exist in the structure. The results of MTT assay indicate that the title compound displays excellent antiproliferative activity against two human cancer cell lines.