Structural Conditionality of the Ionic Conductivity of MTiORO<Subscript>4</Subscript> (M = K,Rb; R = P,As) Single Crystals

The ionic conductivity σ_||c along the crystallographic axis c and the structural imperfection of the lattices of KTiOPO₄, RbTiOPO₄, and RbTiOAsO₄ single crystals with low defect concentration, grown by the high temperature solution growth technique, have been investigated by impedance spectroscopy and X-ray diffraction analysis. Isomorphic substitutions of Rb⁺ ions for conduction K⁺ cations in MTiOPO₄ crystals decreases the σ_||c value, whereas the substitution of As⁵⁺ ions for framework P⁵⁺ cations in RbTiORO₄ crystals increases the σ_||c value. The σ_||c values at 573 K are found to be 1.0 × 10^–5, 5.7 × 10^–6, 2.0 × 10^–6, and 3.3 × 10^–5 S/cm for the KTiOPO₄, RbTiOPO₄ {100}, RbTiOPO₄ {201}, and RbTiOAsO₄ crystals, respectively (the growth zone of the crystalline boule from which the samples were cut is indicated in braces).     

Ionic Conductivity of KTiOPO<Subscript>4</Subscript> Single Crystals Grown by Flux Crystallization under Different Conditions

The ionic conductivity of three KTiOPO₄ crystals grown from high-temperature solution–melts in combination with the Czochralski technique under different conditions has been investigated. The first crystal was obtained at a cooling rate V_g = 0.2–0.5 mm/day and a ratio of potassium and phosphorus concentrations in the solution–melt [K]/[P] = 2. The other two crystals were grown at a much higher velocity (V_g = 3–7 mm/day) from solution–melts with [K]/[P] = 1.5 and 1. It is shown that the crystal grown upon slow cooling at [K]/[P] = 2 has the lowest ionic conductivity: σ_||c = 1.0 × 10^–5 and 3 × 10^–11 S/cm at 573 and 293 K, respectively.     

Structure and properties of niobium-doped potassium titanyl phosphate crystals

A series of potassium titanyl phosphate crystals, KTiOPO₄, with various concentrations of niobium dopant has been grown, and some of their physical properties and structural characteristics have been studied. The incorporation of a small amount of niobium results in considerable changes in the electrical conductivity of KTP: Nb crystals and the temperature of the ferroelectric phase transition. Thus, the presence of 3–4 at. % of niobium results in an increase of conductivity by more than an order of magnitude, whereas T _C decreases from 930 to 620°C. The X-ray diffraction study of the crystals has been performed at room temperature; the neutron diffraction analysis was made at temperatures of 20, 330, and 730°C. It was revealed that two crystallographically independent positions are statistically (by 90%) occupied by potassium cations, which results in the concentration of potassium atoms in the structure higher than it was expected from the condition of preservation of crystal electroneutrality. At high niobium concentrations, the monoclinic compound of the composition K₂TiNb₂P₂O₃ is formed.     

Naphthaceno[5,6-cd]-1,2-dithiole,C18H10S2

C₁₈H₁₀S₂,M=290.34, monoclinic,P2₁,a=20.556(5),b=15.843(3),c=3.963(1) Å,β=92.79(2)° at 18°C,Z=4,D _x =1.496 g cm^?3,μ(Cu Kα)=3.53 mm^?1. Full-matrix least-squares refinement resulted in a final conventionalR value of 0.036 for 2030 observed reflections. The average C-S bond distance is 1.747(16) Å, the S-S bond length is 2.074(1) Å. The torsion angles at the disulfide group are close to zero, at 3.5 and 0.8°. The carbon frameworks are nearly planar, and closely approximate symmetrymmm. Bond distances are comparable with those in related molecules.     

The molecular and crystal structure of 2-oxo-1-pyrrolidine-acetamide

C₆H₁₀N₂O₂, P1 , a = 6,607(2) Å, b = 8,538(2) Å, c = 6,392(2) Å, α = 102,43(2)°, β = 91,11(2)°, y = 79,82(2)°, V = 349,1 ų, Z = 2, D_m = 1,36 g × cm⁻³, D_x = 1,35 g × × cm⁻³, MoKα radiation, λ = 1.71069 Å, μ(MoKα) = 1.11 cm⁻¹. The structure was solved by direct methods. The parameters were refined by full matrix least squares technique to a final R = 0.088 for 834 reflections with ∥F₀∥ > 4σ(F₀). The dihedral angle between the least-squares plane through the pyrrolidine ring and that through the acetamide group is 90.4°. The N H … O hydrogen bonds connect molecules to form bands parallel to the z axis.     

Effect of rhodium incorporation in KTiOPO4 single crystals grown from self‐flux

The presence of an impurity like rhodium in the platinum crucible used for the growth of KTiOPO₄ (KTP) single crystals can have severe consequences in the performance of devices made from these crystals. In the present study the effect of rhodium incorporation has been investigated. Rhodium‐incorporated KTP crystals have a lower ionic conductivity (1.3 × 10^–7 S/cm at 100 kHz) than pure KTP crystals (3.5 × 10^–6 S/cm at 100 kHz) along the c‐axis. And the optical absorption in the green‐wavelength regime leads to a detrimental effect on their SHG performance. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The molecular structures of two furanoheliangolides

The heliangolide-class sesquiterpene lactone 8β-angeloyloxy-9α-acetoxycalyculatolide, C₂₂H₂₆O₈,1, crystallizes in orthorhombic space groupP2₁2₁2₁ witha=12.455(3),b=12.601(3),c=14.023(5) Å,V=2200(1)Å,³ Z=4.R=0.059 for 1735 observed data. The 11,13-dihydro-11α, 13-epoxyatripliciolide-8β-angelate, C₂₀H₂₂O₇. 1/2 H₂O,2, crystallizes as the hemihydrate with two molecules in the asymmetric unit in triclinic space groupP1 witha=9.422(1),b=9.559(1),c=12.358(3) Å, α=101.62(2)°, β=91.30(2)°, γ=117.80(1)°,V=955.6(7)ų,Z=2.R=0.046 for 3607 observed data. In both, the 10-membered rings adopt approximate chair-boat conformations. Their conformations are typical for heliangolides. The methyl group C14 is α, while the C-15 has a β-orientation. The α-methylene-γ-lactone istrans-fused at C6 and C7 with H6 β and H7 α. In compound2, the epoxide at C11–C13 has an α orientation.     

Synthesis and Crystal Structure of 5,7,12,13b,13c,14-Hexahydro-1,4,-dibromo-8,11-dimethoxy-13b,13c-bis(ethoxycarbonyl)-6H,13H-5a,6a,12a,13a-tetra azbenz[5,6]azuleno[2,1,8-ija]benz[f]azulene-6,13-dione

The title compound has been synthesized by the reaction of 4 with 1,4-dimethoxybenzene. The yielded product 5 was investigated with X-ray crystallographic, NMR, EI-MS, and IR techniques. The crystal belongs to a monoclinic system, space group P2₁/c with unit cell parameters a = 12.7790(17) Å, b = 21.565(3) Å, c = 12.2544(16) Å, α = 90°, β = 107.014(2)°, γ = 90°, V = 3229.3(7) Å³, Z = 4, D_c = 1.661, M_r = 807.32, μ = 2.732 mm^?1, F(000) = 1632, R₁ = 0.0540 and wR₂ = 0.0989.     

The Simultaneous Presence of Different Varieties of Intermolecular Hydrogen Bonds in a New Layer-Type Anionic Host Lattice Built of Thiourea,Fumaric Acid and Fumarate Anion

A new inclusion complex (n-C₄H₉)₄N⁺C₄H₃O ₄ ^?  · C₄H₄O₄ · (NH₂)₂CS has been prepared and characterized by X-ray crystallography. Crystal data: space group P \( \overline 1 \), a = 8.799(2) Å, b = 9.590(1) Å, c = 18.684(4) Å, α = 89.63(1)°, β = 79.56(1)°, γ = 79.74(1)°, V = 1525.2(5) ų, Z = 2, R ₁ = 0.0562 and wR = 0.1033. In the title compound, thiourea molecules, fumaric acid and fumarate anions are joined together by typical O–H···O, N–H···O and N–H···S, plus weak C–H···O and C–H···S, hydrogen bonds to generate a hydrogen-bonded layer corresponding to the (100) family of planes. The tetra-n-butylammonium cations are orderly arranged in a sandwich-like packing mode between the stacked layers. The simultaneous presence of different varieties of intermolecular hydrogen bonds is an interesting feature of the title compound.     

Exploration on nano-composite fumed silica-based composite polymer electrolytes with doping of ionic liquid

Fumed silica (SiO₂)-based composite polymer electrolytes were prepared by means of solution casing technique. Horizontal attenuated total reflectance-Fourier Transform Infrared (HATR-FTIR) study shows the complexation between polymer matrix and SiO₂. The highest ionic conductivity of (4.11 ± 0.01) × 10^? 3 Scm^? 1 is achieved upon inclusion of 8 wt.% of SiO₂. Three different regions have been observed in the frequency dependence–ionic conductivity study. The conductivity rises sharply with frequency at low frequency regime. It is followed by a frequency independent plateau region and sharp decrease in the conductivity at high frequency range. The dielectric permittivity (ε^') and dielectric loss (ε^") are decreased with increasing the frequency. This phenomenon is mainly attributed to the electrode polarization effect. The formation of electrical double layer has been proven in these dielectric permittivity studies. This indicates the non-Debye properties of the nano-composite polymer electrolytes.     

Crystal Structures of Diphosphinated Chromium Fischer Amino Carbenes

The crystal structures of four new diphosphinated chromium Fischer amino carbenes with the compositions fac-[(P-P)(CO)₃Cr=C(NR₂′)(R)] (R = Me, NR₂′ = pyrrolidino, P-P = dppe, 1; R = Me, NR₂′ = pyrrolidino, P-P = dppp, 2; R = Me, R′ = Me, P-P = dppe, 3; R = Me, R′ = Me, P-P = dppp, 4) have been determined at 243 K. Compound 1 crystallizes in the monoclinic system, space group P2₁ /n with a = 12.1597(11) Å, b = 20.1556(17) Å, c = 14.0557(12) Å, β = 114.163(3)°, V = 3143.0(5) Å³, and Z = 4. Compound 2 crystallizes in the triclinic system, space group P ? 1 with a = 7.4424(3) Å, b = 10.8830(5) Å, c = 20.6040(9) Å, α = 100.9880(10)°, β = 91.7650(10)°, γ = 97.6610(10)°, V = 1620.90(12) Å³, and Z = 2. Compound 3 crystallizes in the monoclinic system as a mono-solvate of d⁵-pyridine, space group P2₁ /c with a = 11.485(2) Å, b = 22.825(5) Å, c = 14.092(3) Å, β = 108.53(3)°, V = 3502.7(12) Å³, and Z = 4. Compound 4 crystallizes in the orthorhombic system, space group P2 ₁ 2 ₁ 2 ₁ with a = 8.359(3) Å, b = 15.364(6) Å, c = 23.784(9) Å, V = 3055(2) Å³, and Z = 4. Steric repulsions with the diphosphine ligand favor a conformation with the amino moiety directed away from the diphosphine backbone in 1–4.     

Ionic conductivity of binary fluorides of potassium and rare earth elements

The ionic conductivity s of KYF₄ and K₂RF₅ single crystals (R = Gd, Ho, Er) and KNdF₄ and K₂RF₅ ceramic samples (R = Dy, Er) has been studied in the temperature range of 340–500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare earth elements were synthesized by the hydrothermal method (temperature 480°C, pressure 100–150 MPa) in the R₂O₃–KF–H₂O systems. The σ values of tetraf luorides are 3 × 10^–5 S/cm (KYF₄ single crystal) and 3 × 10^–6 S/cm (KNdF₄ ceramics) at 435°C. A K₂ErF₅ single crystal with σ = 1.2 × 10^–4 S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K₂HoF₅ single crystals, σ_∥c/σ_⊥c = 2.5, where σ_∥c and σ_⊥c are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction.     

Structure of antitumor agents 2-acetylpyridinethiosemicarbazone hemihydrate and 2-acetylpyridinethiosemicarbazone hydrochloride

The structures of two antitumor agents, 2-acetylpyridinethiosemicarbazone hemihydrate (1), C₁₈H₁₁N₄O_0.5S, colorless,M _r 203.3, monoclinic,P2₁ lc,a=16.713(3),b=9.460(2),c=12.642(2) Å, β=97.60(1)°,V=1981.2(6) ų,Z=8,R=0.054,R _w =0.085 and 2-acetylpyridinethiosemicarbazone hydrochloride (2), C₁₈H₁₂N₄SCl, yellow,M _r =230.7, monoclinic,P2₁ ln,a=7.676(2),b=7.889(1),c=17.452(4), Å, β=100.96(2)°,V=1037.5(4) ų Z=4,R=0.041,R _w =0.076, have been determined. Both compounds exhibit an E configuration(S atomtrans to the N atom of the hydrazine group). Three hydrogen bonds link the two crystallographically independent molecules in a pairwise fashion in the hemihydrate. An intramolecular N?H...Cl bond lends extra conformational stability to the hydrochloride salt.     

X-ray crystal structure of dichloropicric acid

Dichloropicric acid is orthorhombic, space groupP2₁2₁2₁; at 24°a=5.672(3),b=8.044(3),c=22.491(7) Å,D _x=1.929(2) g-cm^?3,V=1026(1) ų,Z=4. The phenolic OH group is intramolecularly hydrogen bonded to one of theortho nitro groups with an O...O distance of 2.524(5) Å. As a consequence, this nitro group is twisted out of the plane of the benzene ring by only 20.1° in spite of crowding by the adjacent chlorine atom which is only 2.764(3) Å from the O atom in the nitro group. The two non-hydrogen bonded nitro groups have twist angles of 73.9 and 84.1°. There is no evidence of intermolecular hydrogen bonding with any adjacent dichloropicric acid molecule.     

Electrical characterizations of silver chalcogenide glasses

We present a study of the electrical properties of silver chalcogenide glasses ‘40AgI’–30Ag₂S–30GeS₂, 45AgI–27.5Ag₂S–27.5GeS₂ and 50AgI–25Ag₂S–25GeS₂ in the 77–400 K temperature and the 20 Hz to 1 MHz frequency ranges. In our temperature range, a large variation of the real permittivity is observed, in relation with an electrodes polarization effect. As the amount of silver iodide increases in the Ag₂S–GeS₂ matrix, the glass transition temperature and the activation energies decrease, the electrical conductivity increases and reaches 4 Ω⁻¹ m⁻¹ at room temperature for the glass with 50% AgI. The study of the conductivity shows a behavior due to a high ionic conductivity, thermally activated with E_dc = 0.21 eV, E₁ = 0.075 eV (40AgI–30Ag₂S–30GeS₂, 45AgI–27.5Ag₂S–27.5GeS₂), E_dc = 0.17 eV, E₁ = 0.055 eV for 50AgI–25Ag₂S–25GeS₂. For these glasses, we have seen three conductivity regimes. The first two terms are thermally activated. The third term cannot be actually clearly identified because either it is thermally activated with a very low activation energy and frequency dependent, or it is almost non-thermally activated and frequency dependent.     

Ion transport studies in CuI-doped silver borovanadate glassy system

In the present report, ionic transport properties and microstructural investigations of superionic materials in a cost-effective glassy system xCuI–(100 ? x)[2Ag₂O–0.7V₂O₅–0.3B₂O₃], where x = 30, 40, 45, 50 and 60, have been described. The temperature dependent electrical conductivity studies were carried out by ac impedance analysis. The microstructure of the materials studied by SEM indicated the presence of dispersed CuO and AgI micro-crystals in the silver oxysalt glass matrix. High room temperature electrical conductivity of 3.58 × 10^?3 S cm^?1 and low activation energy of 0.24 eV were obtained for the best conducting composition. The ac impedance data were analyzed using impedance and modulus formalisms. These materials show extremely high t_i value of 0.999 and the ionic conductivity is apparently due to Ag⁺ ions only. The use of two glass formers helped to form materials with higher T_g, higher thermal stability and better ionic transport properties.     

Crystal structure of the new radical cation salt (<Emphasis Type="Italic">DOET</Emphasis>)<Subscript>4</Subscript>[Fe(CN)<Subscript>5</Subscript>NO]<Subscript>1.25</Subscript>(C<Subscript>6</Subscript>H<Subscript>5</Subscript>Cl)<Subscript>0.75</Subscript>

A new radical cation salt based on 4,5-(1,4-dioxanediyl-2,3-dithio)-4′,5′-ethylenedithiotetrathiafulvalene (DOET) with the photochromic anion [Fe(CN)₅NO]^2?, namely, (DOET)₄[Fe(CN)₅ NO]_1.25(C₆H₅Cl)_0.75, is synthesized. Single crystals of this salt are studied using X-ray diffraction [a = 10.398(2) Å, b = 11.168(2) Å, c = 18.499(4) Å, α = 103.14(3)°, β = 92.80(3)°, γ = 106.02(3)°, V = 1996.3(7) ų, space group \(P\bar 1\), and Z = 1]. In the structure, radical cation layers alternate with anion layers along the c axis. The centrosymmetric dimers are formed by DOET radical cations in the donor layer with packing of the β type. Like the vast majority of DOET-based salts, the new salt possesses semiconductor properties.     

Reduction of bulk and interface defects by network self-organizations in gate dielectrics for silicon thin film and field effect transistors (TFTs and FETs,respectively)

Studies of binary chalcogenide alloys have established that the onset of network rigidity is generally delayed by a network self-organization resulting in an intermediate phase with significant deviations from mean-field chemical bonding. In Ge_xSe_1−x, the onset of local chemical bonding rigidity occurs for a mean-field coordination, r_c = 2.4 at x = 0.2, but percolation of stress resulting in network rigidity is delayed until r_c = 2.52. This paper demonstrates that low levels of electrically active defects in gate dielectrics for (i) thin film transistors (TFTs) in liquid crystal displays (LCDs), and (ii) aggressively-scaled metal- oxide-semiconductor field effect transistors (MOSFETs) are derived from similar network self-organizations that occur for a narrow range of dielectric compositions. The dielectrics of this article are non-crystalline (nc-) Si_xN_yH_z alloys in which a chemical self-organization occurs during deposition at 300 °C, and nc-(SiO₂)_x(Si₃N₄)_y(ZrO₂)_z alloys in which it occurs during post-deposition annealing at ∼900 °C. For each of these alloys, the values of x, y and z, are approximately 0.3, 0.4 and 0.3.     

Crystal structure of the antidepressant noxiptyline hydrochloride (5-dimethylaminoethyloximino-5H-dibenzo[a,d]-cyclohepta-1,4-diene hydrochloride)

The crystal structure of noxiptyline hydrochloride C₁₉H₂₃N ₂ ⁺ OCl^? (5-dimethylaminoethyloximino-5H-dibenzo[a,d]cyclohepta-1,4-diene hydrochloride), is monoclinic:P2₁/c, a=15.894(5),b=9.116(2),c=13.755(4) Å,β=113.00(7)°,Z=4. It has been determined by application of a multisolution direct method procedure, and refined by full-matrix least squares to a conventionalR of 0.056 for 1674 counterreflections (to 2Θ=44°, MoKα radiation). The noxiptyline molecule adopts a folded boat conformation with dihedral angle between benzo-group planes of 129.3°, and the atypical dimethylaminoethyloximino side chain adopts agauche-gauche distribution about the O-C_β and C_α-C_β bonds. The only intermolecular approach less than van der Waals distances is the hydrogen bond between the amine nitrogen atom and the chloride ion.     

Synthesis,Spectroscopic and Crystal Structure Analysis of <Emphasis Type="Italic">N</Emphasis>-[imidazolidin-2-ylidene]-5-(thien-2-yl)[1,3,4]thiadiazole-2-amine

The crystal structure of the title compound has been determined. The compound crystallizes in the monoclinic space group P2₁/c with a = 5.9885(2) Å, b = 14.7345(4) Å, c = 12.3719(4) Å, β = 96.655(5)°, V = 1084.31(8) Å³, z = 4. An intramolecular N–H···N hydrogen bond forms a pseudo-six-membered ring with graph set S ¹ ₁(6). The crystal structure is stabilized by intermolecular interactions of the type N–H···N and C–H···N. The packing motifs in accordance with Etter’s analysis are R ² ₂(8) corresponding to N–H···N dimer and that generated by the chain is C(7).