Analysis of oxygen shell splitting in hydrothermally grown single crystal ThO2(200)

Single crystals of ThO₂ have been synthesized using hydrothermal growth and studied using the X‐ray absorption fine structure (XAFS) technique. The extended X‐ray absorption fine structure (EXAFS) has been extracted from the XAFS and analyzed using a novel, computational Latin hypercube sampling method. The methodology not only confirms the expected space group and crystal structure, it also identifies the origin of a previously reported split O shell. Since EXAFS is a local order analysis technique, the O shell splitting is identified as an O atom occupying an interstitial site. This result is significant for examining O^2– transport in a ThO₂ matrix and corroborating research indicating partial Th 5f occupancy that is similar to hyper‐stoichiometric UO_2+x compounds. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Fluidized and vibrofluidized shallow beds of fresh leaves

The fluid dynamics behavior of shallow fluidized and vibrofluidized beds operating with fresh leaves was investigated with the aim of exploring drying applications in a modified conveyor belt (MCB) system,which may be operated in a fixedor fluidized-bed mode.Leaves of the specimens Duranta repens,Schinus molle,Coleus barbatus,Buxus sempervirens,and Bougainvillea spectabilis were tested with a range of sphericities from 0.063 to 0.213,bulk densities from 0.038 to 0.251 g/cm 3,apparent densities from 0.52 to ...     

Structural Characterization of Pb6Sb6Se17

The ternary selenide Pb₆Sb₆Se₁₇ was synthesized hydrothermally from the binaries (PbSe and Sb₂Se₃) and crystallizes in the orthorhombic space group Pbam (a = 15.835(3), b = 24.043(5), c = 4.134(2)Å, Z = 2). The main building blocks of the crystal structure are ribbons made of square pyramidal [(Pb,Sb)Se₅] groups running along [010].     

Enhancement of second harmonic generation efficiency: Growth and characterization of magnesium(II)-doped tetrakis(thiourea)nickel(II) chloride crystals

The influence of magnesium doping on the properties of tetrakis(thiourea)nickel(II) chloride crystals has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the alkaline earth metal are observed by scanning electron microscopy. The incorporation of Mg(II) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The crystal is further characterized by Kurtz powder technique and dielectric studies.     

Hydrothermal Synthesis and Single Crystal Structures of New Thorium Fluorides: A<Subscript>3</Subscript>Ba<Subscript>2</Subscript>Th<Subscript>3</Subscript>F<Subscript>19</Subscript> (A = Na,K, Rb)

Abstract  

A new family of mixed alkali–alkaline earth metal thorium fluorides based on the formulation A₃Ba₂Th₃F₁₉ (A = Na, K, Rb) has been synthesized and structurally characterized. The compounds crystallize in the cubic space group Im-3m with a = 12.1222 (14) and 12.3052 (14) ? for the K and Rb end members, respectively. This is only the second thorium fluoride reported as a single crystal structure to incorporate alkali and alkaline earth metals into the same structure. Crystals were obtained from the equimolar reaction of Ba(OH)₂·H₂O, ThF₄ and ABF₄ in a 2 M AF solution under hydrothermal conditions (545 °C and 1 kbar). Barium atoms substitute at the alkali metal sites and preferential site substitution is supported by the crystallographic analysis. Additional substitution at the alkali metal site has also been shown for K_2.2Na_0.8Ba₂Th₃F₁₉ and K_1.85Rb_1.15Ba₂Th₃F₁₉ using dissimilar alkali tetrafluoroborate and fluoride mineralizers in the reaction.     

Protonation and protolysis of [Fe4(CO)12(CCH3)]−

The reaction of [Fe₄(CO)₁₂(CCH₃)]^? with HSO₃CF₃ in CH₂Cl₂ solution yields the compound HFe₄(CO)₁₂(CCH₃), which was characterized chemically, spectroscopically and by single crystal X-ray diffraction. This compound retains the approximately tetrahedral 4-iron framework characteristic of the parent anion and protonation appears to have occurred on an FeFe bond. In neat HSO₃CF₃, infrared and NMR spectroscopic evidence indicates that another proton adds to the metal framework producing [H₂Fe₄(CO)₁₂(CCH₃]⁺. On long standing, this solution evolves CO, and H₂, and small amounts of CH₄ and C₂H₆. On the time scale of the experiments described here the latter two gases are obtained in an approximately $\text{1}\text{3}$ ratio. Deuterated acid leads to mixtures of the various isotopomers of CH₄ but the ethane is CD₃CH₃. Possible mechanisms for hydrocarbon production are discussed.     

Influence of transition metal doping on tris(thiourea)zinc(II) sulphate crystals

Optical, thermal and dielectric properties of Ni(II)-doped tris(thiourea)zinc(II) sulphate single crystals grown by slow evaporation solution growth technique has been investigated. The lattice parameters of the as-grown crystals were obtained by single crystal X-ray diffraction analysis. The modes of vibrations of different functional groups present were identified by FT-IR studies. The surface morphological changes are observed in the doped specimen. The structure and the crystallinity of the material were confirmed by powder X-ray diffraction analysis. The UV–vis optical absorption spectrum shows the lower optical cut-off at ∼284 nm and the crystals are transparent in the entire visible region. The relative second harmonic generation efficiency measurements reveal the enhancement of efficiency by doping with small quantities of Ni(II).