Strontium hexabromodicadmate(II) octahydrate

The ternary system SrBr₂–CdBr₂–H₂O was investigated at room temperature. The title phase, SrCd₂Br₆·8H₂O, has been isolated from this system and its structure determined by single‐crystal X‐ray diffraction. The structure consists of infinite double chains of CdBr₆ octahedra and chains of Sr(H₂O)₉ polyhedra packed along the b axis. The interaction between these two isolated chains occurs through O—H⃛O and O—H⃛Br hydrogen bonds. The structure is compared with that of SrCd₂Cl₆·8H₂O.     

Synthesis and characterizations of new morphological ZnO and Ce-doped ZnO powders by sol–gel process

ZnO micro-tori and cerium-doped hexangulars ZnO have been prepared by the sol–gel method under methanol hypercritical conditions of temperature and pressure. X-ray diffraction (XRD) measurement has revealed the high crystalline quality and the nanometric size of the samples. Scanning electron microscopy (SEM) has shown that the ZnO powder has a torus-like shape while that of ZnO:Ce has a hexangular-like shape, either standing free or inserted into the cores of ZnO tori. Transmission electron microscopy (TEM) has revealed that the ZnO particles have sizes between 25 and 30 nm while Ce-doped ZnO grains have diameters ranging from 75 nm to 100 nm. It is demonstrated from photoluminescence (PL) spectra at room temperature that the introduction of cerium in ZnO reduces the emission intensity lines, particularly the ZnO red and green ones.     

Investigations of the half-metallic behavior and the magnetic and thermodynamic properties of half-Heusler CoMnTe and RuMnTe compounds: A first-principles study

First-principles spin-polarized density functional theory （DFT） investigations of the structural, electronic, magnetic, and thermodynamics characteristics of the half-Heusler, CoMnTe and RuMnTe compounds are carried out. Calculations are accomplished within a state of the art full-potential （FP） linearized （L） augmented plane wave plus a local orbital （APW ＋ lo） computational approach framed within DFT. The generalized gradient approximation （GGA） parameterized by Perdew, Burke, and Ernzerhof （PBE） is implemented as an exchange correlation functional as a part of the total energy calculation. From the analysis of the calculated electronic band structure as well as the density of states for both compounds, a strong hybridization between d states of the higher valent transition metal （TM） atoms （Co, Ru） and lower valent TM atoms of （Mn） is observed. Furthermore, total and partial density of states （PDOS） of the ground state and the results of spin magnetic moments reveal that these compounds are both stable and ideal half-metallic ferromagnetic. The effects of the unit cell volume on the magnetic properties and half-metaliicity are crucial. It is worth noting that our computed results of the total spin magnetic moments, for CoMnTe equal to 4 ~tB and 3 p-B per unit cell for RuMnTe, nicely follow the rule μ2tot = Zt - 18. Using the quasi-harmonic Debye model, which considers the phononic effects, the effecs of pressure P and temperature T on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and heat capacity for these compounds are investigated for the first time.     

H2-broadening,shifting and mixing coefficients of the doublets in the ν2 and ν4 bands of PH3 at room temperature

The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν₂ and ν₄ bands of PH₃ perturbed by H₂ have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH₃), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν₂ and ν₄ bands of PH₃ perturbed by hydrogen (H₂) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A₁ and A₂ doublet lines with quantum numbers K = 3n,?(n = 1,?2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.     

Potassium cerium(III) bis­(sulfate) monohydrate,KCe(SO4)2·H2O

The crystal structure of potassium cerium(III) bis­(sulfate) monohydrate, KCe(SO₄)₂·H₂O, is built up from irregular independent SO₄ tetra­hedra, CeO₉ polyhedra in the form of distorted tricapped trigonal prisms and K⁺ ions. Hydrogen bonding between the free water mol­ecule and sulfate groups supplement the ionic bonds characteristic of the rest of the structure.     

Prediction study of the structural,elastic, electronic and optical properties of the antiperovskite BiNBa3

We use an ab initio full-potential linear muffin-tin orbital method within the local density approximation (LDA) to study the structural, elastic, electronic and optical properties of the antiperovskite BiNBa₃. The calculated lattice parameter is in good agreement with previous calculations. The elastic constants and their pressure dependence are calculated; we found a linear dependence of elastic stiffness on the pressure. We estimated the Debye temperature of this compound from the average sound velocity. We also present results of the effective masses for the electrons in the conduction band (CB) and the holes in the valence band (VB). To complete the fundamental characteristics of this compound we have analyzed the optical properties.     

Activated sulfahydantoin as Boc-glycine enolate equivalent: highly diastereoselective α-hydroxyalkylation and application to the synthesis of aldopentonate analogues

N-Boc-activated sulfahydantoin can be seen as glycine enolate equivalent. It appeared as a convenient starting material for the stereocontrolled preparation of threonine homologues through an alkaline syn aldolization involving a Boc migration. The methodology allowed the one-pot preparation of constrained analogues of polyoxamic acid.