Crystal structure of NH3(CH2)2NH3BiCl5·2H2O

The ethylenediammonium pentachlorobismuthate(III) dihydrate salt is monoclinic with the following unit cell dimensions: a = 10.902(8)Å, b = 7.926(6)Å, c = 15.199(6)Å, = 96.40(1)°, space group P2₁/n with Z = 4. The structure shows a layer arrangement parallel to the axis: planes of the [Bi₂Cl₁₀]^4– bioctahedra alternate with planes of [NH₃(CH₂)₂NH₃]²⁺ dications. The [Bi₂Cl₁₀]^4– bioctahedra are connected through O(W)–H··· Cl hydrogen bonds, so that infinite unidimensional chains of composition [Bi₂Cl₁₀(H₂O)₂] _n ^4n– are formed in the structure parallel to the axis. These chains are themselves interconnected by means of the N–H···Cl bonds originating from the [NH₃(CH₂)₂NH₃]²⁺ entities, forming a three-dimensional network.     

Synthesis,crystal structure and dielectric properties of C6H18N2SbCl5

The result of the X‐ray diffraction, differential scanning calorimetry and dielectric studies on a new crystal material C₆H₁₈N₂SbCl₅ is presented. The new organic–inorganic compound has been synthesized and characterized by the X‐ray diffraction method at 296(2) K. It crystallizes in the monoclinic P21/n space group. The cell dimensions are: a = 5.8617(1) Å, b = 15.7069(2) Å, c = 16.6693(2) Å, β = 97.627(1)° and Z = 4. The crystal structure consists of a discrete ionic layer of (C₆H₁₈N₂)²⁺ cations and [SbCl₅]^2? anions linked via simple and bifurcated N―H · · · Cl hydrogen bonds. DSC analysis shows that this compound undergoes a phase transition at about (384 ± 2) K. AC and DC conductivities, complex dielectric permittivity ε*(ω) and complex electrical modulus M*(ω) were respectively studied as temperature and frequency functions. The combined data support each other and confirm the existence of a structural phase transition at about 384 K. Moreover, the temperature dependence of the DC conductivity and relaxation frequency followed the Arrhenius relation. The frequency dependence of the real part of the AC conductivity in both phases follows the Jonscher's universal dynamic law: . The behavior of s(T) with temperature suggests that the hopping over barrier model (CBH) and the small polaron tunneling mechanism (SPTM) prevail in phases I and II, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

On the sensitivity analysis of porous material models

Porous materials are used in many vibroacoustic applications. Different available models describe their behaviors according to materials' intrinsic characteristics. For instance, in the case of porous material with rigid frame, and according to the Champoux–Allard model, five parameters are employed. In this paper, an investigation about this model sensitivity to parameters according to frequency is conducted. Sobol and FAST algorithms are used for sensitivity analysis. A strong parametric frequency dependent hierarchy is shown. Sensitivity investigations confirm that resistivity is the most influent parameter when acoustic absorption and surface impedance of porous materials with rigid frame are considered. The analysis is first performed on a wide category of porous materials, and then restricted to a polyurethane foam analysis in order to illustrate the impact of the reduction of the design space. In a second part, a sensitivity analysis is performed using the Biot–Allard model with nine parameters including mechanical effects of the frame and conclusions are drawn through numerical simulations.     

X-ray,optical, vibrational,electrical, and DFT study of the polymorphic structure of ethylenediammonium bis iodate α-C2H10N2(IO3)2 and β-C2H10N2(IO3)2

The interaction of ethylenediamine with iodic acid by the slow evaporation method at room temperature gives rise to the crystals of α-C₂H₁₀N₂(IO₃)₂ and β-C₂H₁₀N₂(IO₃)₂ denoted as α-EBI and β-EBI, respectively. The acentric crystal structures of both polymorphs that consist of [C₂H₁₀N₂]²⁺ cations and [IO₃]^? anions connected together by N–H…O hydrogen bonds are discussed and compared. The optical properties of both polymorphs were determined using UV-vis diffuse reflectance spectroscopy (DRS) showing a wide transparency windows. The DFT calculations using the mixed B3PW91/[6–31?+?(d, p), LanL2Dz] basis set of optimized geometries, dipole moment (μ), polarizability (α), first static hyperpolarizability (β), and population analysis were also reported. The experimental and theoretical IR and Raman spectra were compared, and the careful and complete assignment of the vibrational motions of both compounds was undertaken with the aid of potential energy distribution (PED) analysis. DSC and AC conductivity analysis revealed that α-C₂H₁₀N₂(IO₃)₂ and β-C₂H₁₀N₂(IO₃)₂ undergo a first-order phase transition around 360 K. The electrical σ_tot (ω, T) conductivity obeyed to Jonscher’s power law and the temperature dependence of the S(T) parameter showed that the electrical conductivity of both polymorph phases might be treated using the correlated barrier hopping (CBH) model.