tert-Butyl N-[N,N-bis­(2-chloro­ethyl)sulfamo­yl]-N-(2-chloro­ethyl)carbamate

The title compound, C11H21Cl3N2O4S, was produced as part of a development programme of a new synthetic route to chloro­ethyl­nitro­sosulfamides (CENS) with three chloro­ethyl moieties. These compounds possess structural features that confer potential biological activity and act as alkyl­ating agents. The packing is governed by four weak C—H⋯O inter­actions, forming an infinite three-dimensional network

Poly[tetraaqua-μ4-squarato-di-μ3-squarato-disam­arium(III)]

The structure of the title compound, [Sm2(C4O4)3(H2O)4]n, consists of infinite-chain structural units, built from edge-sharing samarium SmO7(H2O)2 polyhedra and linked via bis-monodendate squarate (sq1) groups. The chains extend along [100] in a zigzag mode and are interconnected by bis-chelating squarate (sq2) ligands into layers parallel to (101). Inter­layer hydrogen bonds strengthen the cohesion of the three-dimensional network. The samarium cation is coordinated by four O atoms from sq1 units and three O atoms from sq2 units, in addition to two water O atoms. The best representation of the samarium SmO7(H2O)2 polyhedron is distorted tricapped trigonal-prismatic. The sq1 ligand has one metal-free O atom and relates three Sm atoms in a bis-monodentate and chelation fashion, the second squarate, sq2, is strictly centrosymmetric and acts as a bis-chelating ligand

Specific trends in phosphate glass crystallization

This paper focusses on investigating and comparing the congruent crystallization of phosphate glasses with different degrees of polymerization. The study was performed both on powders, with different size fractions, and coarse particles which can be assimilated to bulk. From DSC experiments, corroborated by SEM analysis, it was demonstrated that LiPO3 crystallizes from surface whereas LiGe2(PO4)3 crystallizes in the whole volume. Sn2P2O7 presented both phenomena, the nucleation time lag being short enough to observe internal crystallization at the laboratory time scale. Using the non-isothermal Ozawa method, the kinetic parameters of the overall devitrification process were determined in terms of the Avrami exponent and of the activation energy for crystallization. The temperature of the maximum nucleation rate was calculated by using the nucleation adiabatic theory. For the achievement of this calculation, the heat capacity temperature dependence up to melting was determined from DSC experiments. The results were found in a good agreement with the SEM observation and the results of the non-isothermal crystallization study.acceptedVersionPeer reviewe

Bis(creatininium) tetra­chlorido­cadmate(II)

In the title compound, (C4H8N3O)2[CdCl4], the asymmetric unit comprises two creatininium cations and one tetra­chloridocadmate anion. Cd⋯O secondary bonding links one of the two imidazole rings and the anion into ion pairs. The free and bound cations form layers between which the [CdCl4]2− anions are sandwiched. The CdII atom adopts a distorted trigonal-bipyramidal geometry in which the Cd⋯O bond is axial. Inter­molecular N—H⋯Cl hydrogen bonds form a two-dimensional network parallel to (001) which ensures the junction between creatininium cations and [CdCl4]2− anions

3,4-Dimethyl­anilinium chloride monohydrate

The crystal structure of the title compound, C8H12N+·Cl−·H2O, consists of hydro­phobic layers of dimethyl­anilinium cations parallel to the bc plane alternated by hydro­philic layers of chloride anions and water mol­ecules. The layers are linked by N—H⋯O and N—H⋯Cl hydrogen bonds involving the ammonium groups of the cations. The cohesion of the ionic structure is further stabilized by O—H⋯Cl hydrogen-bonding inter­actions

Macroscopic and micro-structural aspects of the lithium metaphosphate glass crystallization

International audienceThe LiPO3 glass crytallization have been investigated according to isothermal and non-isothermal approaches by using various techniques such as thermal analysis, helium pycnometry, scanning electronic microcospy and X-ray powder diffraction. Different experimental procedures have been developed to determine the crystallized volume fraction. The different results are a good agreement and leadto a better comprehension at a "macroscopic" scale of this first order transition. In addition, from "ex-situ" X-ray powder diffraction experiments, the understanding of the diffraction line intensities as a function of the annealing time, at a fixed temperature, has revealed a new metastable crystalline form of LiPO3 (named alpha) stable over a short time range. Attempts for indexing led to a possible monoclinic system close to that reported in literature for the thermodynamical stable variety (named beta). The micro-structure of annealed samples has been discussed in terms of crystallite sizes and lattice micro-distorsions at a nanometer scale. This study based on diffraction line broadening analysis was carried out with the integral breadth method. Finally, from "in-situ" X-ray powder diffraction experiments, evidence was shown that the LiPO3 glass matrix crystallizes first in a metastable LiPO3-alpha form which, in turn, transforms into the beta form

Characterisation of a new NZP material prepared from reactive sintering of a phosphate based glass

International audienc

Synthesis, characterization and devitrification behaviour of an yttrium containing boroaluminate glass

International audienceThe glass forming region in the B2O3-Al2O3-Y2O3 composition diagram has been determined by a melting and quenching procedure at temperatures up to 1800°C. Different physical characteristics (density, coefficient of thermal expansion, glass transition and crystallization peak temperatures) have been determined for a 35B2O3-40Al2O3-25Y2O3 glass composition (in mol.%). By using a predictive model and some NMR structural data, different elastic moduli (Young's modulus, bulk modulus, shear modulus and Poisson's ratio) have been calculated. The devitrification behaviour has also been studied. Internal crystallization is the dominant mechanism and a new (Y, Al)BO3 ternary phase has been characterized by X-ray powder diffraction. The temperature and time nucleation dependence have been determined from DTA experiments as well as the crystallization kinetics (i.e. the Avrami exponent and the activation energy for crystal growth)

X-ray powder diffraction investigation of new oxynitride precursors: rare earth oxide compounds of fluorite- and sheelite-type structures in the Yb-(Zr,W)-O system

International audienceNanocrystallized oxide precursors of colored (oxy)nitrides related to the system Yb-(Zr-W)-O have been successfully prepared using a chimie douce process--the amorphous citrate route. The process involves first a formation of fine and homogeneous powdered solids obtained by calcination at 600 °C, a temperature much lower than that of the conventional solid-state method. At this stage, the X-ray diffraction patterns exhibit large line broadening effects. Finally, two well-crystallized and pure quaternary oxides have been readily obtained by heating and under annealing conditions at 850 and 900 °C for 12 h. For one of the patterns, all the X-ray diffraction lines can be easily indexed to a cubic phase with the fluorite structure conforming to the Fm3m space group [Yb2Zr1.21W0.41O6.65◻1.35 called C-phase: a=5.1864(2) Å]. The second phase adopts the sheelite-type structure [Yb2ZrWO8 called T-phase: space group I41/a, a=5.1584(5), and c=10.8246(6) Å]. By taking into account the present compositions determined by EDS measurements, Rietveld structure refinements produce final RB factors of 0.015 and 0.044, and Rwp factors of 0.069 and 0.089, respectively. In order to characterize the microstructure of the materials (crystallite size and lattice distortion) at the nanometer scale, a study based on diffraction line broadening analysis applying the whole pattern refinement method was also undertaken with confidence. The results show smooth angular variations of the values of FWHMs, indicating that the microstructural properties are isotropic for the cubic and tetragonal oxides. More precisely, the results indicate that whatever the profile fitting approach used ("profile matching" procedure and Rietveld method), the reliability factors Rwp are systematically better with a combined size strain than with zero strain considerations. The strain magnitudes observed for the C-phase-850 °C as well as for the T-phase-900 °C should be viewed as realistic strain