Superconductivity in the Organic Charge Transfer Salts: (TMTSF)2X and (TMTTF)2X

Abstract

We report pressure dependent studies of the a-axis resistivity as a function of temperature for several members of the isostructural families of organic charge transfer salts, (TMTSF)₂X and (TMTTF) ₂X. For a typical (TMTSF)₂X material the low temperature metal-insulator transition seen at 1 bar is suppressed above some critical pressure, P_c, where a superconducting transition is observed near 1 K. We find a correlation between P_c and the ambient pressure c lattice parameter which reflects the anion size. The (TMTTF) _cX salts exhibit very different ambient pressure behaviour but we find that with the application of sufficiently high pressures (～30 kbar) their behaviour resembles that seen in the (TMTSF)₂X family but at lower pressures. In particular we find evidence of a possible superconducting transition near 4 K in (TMTTF)₂Br at 25 kbar. At this pressure the conductivity near 4 K is extremely high with a value approaching 10⁶ (Ωcm)^?1 and the resistivity ratio is about 400.     

Role of Dimensionality in Dimerized Two-Band Systems

Abstract

We have studied the ground state properties of Pd(dmit)₂ salts using an effective dimer model. This model describes low-energy excitations of the two-band Hubbard model and is derived by a strong coupling expansion. Dimensionality of the Fermi surface, density-of-states singularity, and magnetic frustration in the dimer model are simultaneously controlled by substituting the cation.     

Structural Analysis of the Layered Compounds Cu x TiS2

Abstract

A structural analysis of single crystals of the layered compounds Cu _x TiS₂ (x=0. 0.21 and 0.38), which were prepared by the iodine transport and the electrochemical methods, has been performed by X-ray diffraction. The displacement parameters of Ti and S atoms along the c axis are larger than those along the a axis. It is understood that the intra-layer bonding between Ti-Ti and S-S atoms is stronger than the inter-layer bonding between Ti-and S-layers. Both distances between Ti-and S-layers and between Cu-and S-layers are enlarged without changing the structure of the mother phase after intercalating Cu atoms.     

Crystal Structure and Vibrational Spectra of Erbium Trisodium Bis(Cyclotriphosphate) Nonahydrate,ErNa<Subscript>3</Subscript>(P<Subscript>3</Subscript>O<Subscript>9</Subscript>)<Subscript>2</Subscript> · 9H<Subscript>2</Subscript>O

Abstract The cyclotriphosphate salt, ErNa₃(P₃O₉)₂ · 9H₂O, has been characterized by single-crystal X-ray diffraction [hexagonal, space group , with unit cell parameters of a = b = 30.8451(14), c = 12.8063(8) ?; Z = 18]. The structure consists of alternating layers of [P₃O₉]³⁻ groups, ErO₈ dodecahedra, Na(1)O₆ and Na(2)O₇ polyhedra linked together by water molecules. The P₃O₉ rings are grouped along the c-axis in a P₃O₉–ErO₈ arrangement thereby producing broad, hexagonal channels of diameter of 6.65 ? with a side dimension of 3.907 ?. The absence of coincidences for the majority of the IR and Raman bands observed for the cyclotriphosphate salt is in accord with the centrosymmetric structure of the material. The vibrational spectra have been interpreted on the basis of factor group effects. Graphical abstract We report the crystal structure and vibrational spectra of erbium trisodium bis(cyclotriphosphate)nanohydrate salt ErNa ₃ (P ₃ O ₉ ) ₂ · 9H ₂ O H. Assaaoudi, M. Ijjaali, A. Ennaciri, I. S. Butler* and J. A. Kozinski Crystal structure and vibrational spectra of erbium trisodium bis(cyclotriphosphate) nonahydrate,ErNa₃(P₃O₉)₂ · 9H₂O. Projection of the coordination polyhedra of ErNa₃(P₃O₉)₂ · 9H₂O down the c axis     

Crystal and Molecular Structures of Di-1-Adamantylthiophosphinic Chloride, <Emphasis Type="Italic">P</Emphasis>,<Emphasis Type="Italic">P</Emphasis>-Diphenyl-<Emphasis Type="Italic">N</Emphasis>-Benzyl Phosphinothioic- and Selenoic- Amides

Abstract  Synthesis and X-ray structural determination of three phosphorus compounds are reported. (3b) is monoclinic P2(1)/c with a = 11.852(1), b = 12.825(1), c = 12.445(1) ?, β = 103.693(1)o; (4a) and (4b) are monoclinic P2(1)/n with a = 12.1422(16), b = 9.0860(12), c = 14.845(2) ?, β = 96.498(3)o for (4a), and a = 12.2714(16), b = 9.2812(12), c = 14.800(2) ?, β = 97.176(2)o for (4b). They all exhibit distorted tetrahedral geometry about the P atom. Ph₂P(X)NHC₇H₇ (X=S (4a) and X=Se (4b)) show typical P–S and P–Se double bond distances and P–N single bonds, while P–S bond in 1-Ad₂P(S)Cl (3b) is comparable to P–S single bonded probably due to the largeness of 1-adamantyl groups. Graphical Abstract  Synthesis and X-ray structural determination of 1-Ad₂P(S)Cl (3b), Ph₂P(S)NHC₇H₇ (4a) and Ph₂P(Se)NHC₇H₇ (4b) are reported.      

Photocatalytic properties of TiO2/ZnO thin film

ABSTRACT

TiO₂, ZnO and ZnO/TiO₂ thin films have been prepared by radio frequency magnetron sputtering method under different temperatures. Their photo catalytic activities have been investigated. The structural of the thin films were characterized by X-ray diffraction and Raman spectroscopy. The photo catalytic activities of TiO₂ and ZnO/TiO₂ samples were evaluated by the photo decomposition of methylene blue. We note that the structural proprieties of the thin films showed a perfect crystallization along the (002) for ZnO, Rutile (110) for TiO₂ and Anatase (101) for TiO₂. The experimental results show that the bilayer ZnO/TiO₂ were the most efficient photo catalysts compared to the layer of TiO₂. This increased catalytic effect can attributed to the interface between the ZnO layer and the TiO₂ one, which modify significantly the chemical potential of the bilayer.     

Advanced nanostructure Ti0.7In0.3O2 support enhances electron transfer to Pt: Used as high performance catalyst for oxygen reduction reaction

ABSTRACT

The slow rate of the oxygen reduction reaction (ORR) and the instability of Pt based catalysts are two of the most important issues which must be solved in order to make proton exchange membrane fuel cells (PEMFCs) a reality. Here, we present a new approach by exploring robust non-carbon Ti_0.7In_0.3O₂ used as a novel functionalised co-catalytic support for Pt. This approach is based on the novel nanostructure Ti_0.7In_0.3O₂ support with “electronic transfer mechanism” from Ti_0.7In_0.3O₂ to Pt that can modify surface electronic structure of Pt, owing to a shift in the d-band centre of the surface Pt atoms. The 20 wt% Pt/Ti_0.7In_0.3O₂ catalyst shows high activity than that of that of the commercial 20 wt% Pt/C (E-TEK). Our data suggest this enhancement is a result of both the electronic structure change of Pt upon its synergistic interaction with Ti_0.7In_0.3O₂ and the inherent structural and chemical stability and the corrosion-resistance of the Ti_0.7In_0.3O₂ in acidic and oxidative environments.     

Crystal structure of 5-(p-methoxyphenylamino)indane and AM1 calculations on N-arylamines derivatives, precursors of phenothiazine drugs

The structural determination by X-ray crystallography of the titled N-arylamine 4a, as well as AM₁ calculations on a series of derivatives (4b–c, 5a–c), are reported. The compound 4a is monoclinic P2₁/c with a = 7.656(3), b = 23.655(5), c = 7.686(9) Å, = 112.59(6)°, V = 1285.2(2) ų and Z = 4. This structure has been used as a template for the building of some others derivatives used for AM₁ calculations. The results show that the cyclization position on the aromatic rings, which can lead to two regioisomers, depends on the nature of the benzylic substituants.     

Recent developments in the MOVPE growth of low H content ZnSe-based compounds and heterostructures

The origin of unintentional hydrogen (H) incorporation during metalorganic vapour phase epitaxy (MOVPE) of ZnSe-based compounds is reviewed and discussed. Hydrogen enters in MOVPE-grown ZnSe as a result of alkyls surface reactions, effectively passivating intentional nitrogen (N) acceptors in p-doped ZnSe during the fabrication of blue-light emitting diodes and laser diodes. The existence of a marked trade-off between the proclivity of common Se alkyls to incorporate H and their thermal stability is pointed out. Current strategies to overcome this process limitation are then described along with results achieved and technological drawbacks. The use of a novel class of VI-group alkyl precursors of the form R₂X₂ [where X=Se, S and R is an ethyl (Et) or methyl (Me) radical] is proposed as an alternative solution. These alkyls allow a reduction of H incorporation in ZnSe-based materials, whilst retaining the low temperatures required for the growth of device quality wide band-gap II–VI compounds. Dimethyldiselenide (Me₂Se₂) and diethyldisulphide (Et₂S₂) allow the pyrolytic MOVPE growth of Zn(S)Se compounds below 400 °C. Mass spectrometry fragmentation experiments performed on the alkyl molecular ions allowed to investigate their relative bond strengths and likely decomposition paths. The reduced thermal stability of these alkyls is attributed to a weakening of the XC bonds in the R₂X₂ molecule induced by the stronger XX bond. Secondary ion mass spectrometry (SIMS) analysis showed that as-grown ZnSe have [H]≈(1–3)×10¹⁷ cm⁻³, i.e. among the lowest ever reported for MOVPE-grown layers. The functional validation of the new S and Se alkyls is completed by the structural and optical characterisation of Zn(S)Se-based heterostructures grown on (100)GaAs. High-resolution X-ray diffraction studies are presented along with cathodoluminescence (CL) measurements and compared to what reported in the literature. The epilayer structural properties compare well with that of molecular beam epitaxy and MOVPE grown Zn(S)Se heterostructures. CL spectra of ZnSe epilayers appear of good quality, with pronounced band-edge emissions and reduced deep level contributions. Specific emissions in the spectra of ZnS and ZnSe confirm the occurrence of several impurities in the layers, whose origin can be in part attributed to the yet insufficient purity of the novel alkyls.     

A novel Zn(II) coordination polymer based on tetra-carboxylates ligand and N-donor ligand: synthesis,structure and photocatalytic properties

Abstract

Novel film polymeric composites based on the non-photoconducting polyvinyl butyral with heterometallic complexes (NH₄)_4n{[Cu(en)(H₂O)][P₂Mo₅O₂₃]}_n·3.5nH₂O (1) and (NH₄)_2n{[Cu(en)₂][Cu(en)(H₂O)][P₂Mo₅O₂₃]}_n·3nH₂O (2) [en?=?ethylenediamine] have been prepared. Both compounds are similar and contain Strandberg anions [P₂Mo₅O₂₃]^6– linked to Cu-diamine species. The main structural difference between complexes is the presence of additional bridging [Cu(en)₂] fragments in 2, which provide an extra connectivity between the neighboring polyoxometalates. However, the different saturations and relaxation times of the photoresponse, as well as different activation energies, are shown. The variability of the photoconducting properties can be explained by the influence of a chain rigidity on the transport of non-equilibrium charge carriers.     

Synthesis and structure of 4,7,13,16-tetraoxa-1,10-diaza-5,6-benzocyclooctadeca-11,18-dione monohydrate

4,7,13,16-tetraoxa-1,10-diaza-5,6-benzocyclooctadeca-11,18-dione, C₁₆H₂₂N₂O₆·H₂O, (3) was synthesized under thermal conditions, starting from ,-diamine (1) and ,-diester (2). The hydrate of compound (3) was investigated in the solid state by X-ray structural analysis. Crystal data: monoclinic system, space group P2₁/c,a=12.342(4) Å,b=15.978(7) Å,c=8.960(3) Å, =96.72(3)°,Z=4. The structure was solved by direct methods and refined to finalR=0.056,R _w=0.069 for 1962 observed reflections. The structure exhibits internal hydrogen bonds between the etheral O(16) atom and the neighboring amide group. The water molecule connects diamide molecules by one strong hydrogen bond with carbonyl oxygen, and four weak hydrogen bonds with the amide groups and etheral oxygen atoms.     

The split network analysis for exploring composition-structure correlations in multi-component glasses: I. Rationalizing bioactivity-composition trends of bioglasses

We present a strategy, referred to as “split network” analysis, for assessing the average network polymerization (r_F) and mean number of bridging oxygen (BO) atoms (N?_BO^F) for each individual network former F in multi-component oxide-based glasses, primarily targeting those involving Al, B, P and Si. This requires a priori knowledge about the parameters {r_F, N?_BO^F} of all network builders, but one, whose values are deduced by the split network procedure. We illustrate split-network concepts for establishing composition/structure/bioactivity correlations in Na-Ca-Si-P-O glasses. The cooperating influences on the bioactivity from the average polymerization degree of the silicate network and the amounts of orthophosphate and sodium ions are discussed.     

TMTSF2X Salts. Preparation,Structure and Effect of the Anions

The preparation of the TMTSF molecule and some of its properties are reviewed. The preparation of metallic and superconducting TMTSF X salts is described and some structural aspects are discussed, with emphasis of possible order-disorder transitions when X is a non-centrosymmetric anion. Preliminary results for TMTSF₂ TeF₅ which remain conducting to at least 5 K are presented.     

Structural Phase Transition of an Intercalation Compound Mn1/4NbS2

Abstract

A structural phase transition of an intercalation compound Mn_1/4NbS₂ has been investigated by X-ray diffraction at high temperatures. The lattice parameter c exhibited a discontinuous change at 640K. The superlattice reflections observed below 640K disappeared suddenly above 640K. The phase transition at 640K took an aspect of the first-order phase transition. The precise structure analyses were performed at various temperatures above and below the phase-transition temperature. It was revealed that Mn atoms were arranged in disorder in the high-temperature phase, while the Mn atoms were ordered forming the 2a ₀ × 2a ₀ × c ₀ superlattice in the low-temperature phase. The Nb and S atoms around the ordered Mn atoms slightly shifted from the high-symmetry position in the low-temperature phase. The order parameters were the degree of order of the Mn atoms and the degree of displacement of the Nb and S atoms.     

X-Ray Diffuse Scattering Study of Some (TMTSF)2X and (TMTTF)2X Salts

X-ray diffuse scattering experiments on the superconducting salts (TMTSF)₂X with X = PF₆, AsF₆ and ClO₄ reveal no charge density wave instability, in contrast with the poorly conducting (TMTTF)₂PF₆ salt. New structural phase transitions coinciding with conductivity anomalies are found in (TMTSF)₂NO₃, (TMTSF)₂ReO₄, and (TMTTF)₂ClO₄. It is suggested that they correspond to order-disorder transitions involving the non-centrosymmetric counter ions. Relationships between these structural instabilities and superconductivity are also discussed.     

Synthesis and Crystal Structure of the Fluorite-Related Ruthenate, Trilanthanum Ruthenium Septaoxide La3RuO7

Abstract Single crystals of the lanthanum-containing ruthenate, trilanthanum ruthenium septaoxide, La₃RuO₇, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Cmcm with a = 11.2077(6) ?, b = 7.4531(4) ?, and c = 7.6042(4) ? and is a member of a well-known family of compounds with the general formula Ln₃MO₇. Graphical abstract Synthesis and crystal structure of the fluorite-related ruthenate, trilanthanum ruthenium septaoxide La ₃ RuO ₇ William R. Gemmill, Mark D. Smith and Hans-Conrad zur Loye* Single crystals of La₃RuO₇ were isolated from a high-temperature KCl flux and characterized by single crystal X-ray diffraction. A view of the crystal structure approximately along [001] of La₃RuO₇ and displacement ellipsoids drawn at 50% probability level. The vertex-sharing RuO₆ octahedra are shown in blue, La³⁺ are shown in yellow, and O²⁻ are shown in red.      

Transport and Electrochemical Properties of Bi2Sr2CaCu2O8 Superconductors

Abstract

Electrical conductivity and thermoelectric power measurements (77–300K) of both the pure and electrochemically doped with lithium Bi₂Sr₂CaCu₂O₈ system, are presented. Clear correlation between transport and electrochemical properties of Li_xBi₂Sr₂CaCu₂O₈ was shown.     

Structural and optical properties of TiO2:SnO2 thin films prepared by sol gel method

ABSTRACT

TiO₂:SnO₂ thin films were deposited on glass substrates, by using sol gel spin coating method with different ratio (3%, 5% and 7%) at 3200 rpm, to study their effect on different properties of TiO₂: SnO₂ thin films. The structural and optical properties of films have studied for different ratio. These deposited films have been characterized by various methods such as X-Ray Diffraction (XRD), Ultra Visible spectroscopy. The (XRD) can be used to identify crystal structure of as deposited films. The Transmission spectra have shown the transparent and opaque parts in the visible and UV wavelengths.     

Pharmaceutical Salts of Fluoroquinolone Antibacterial Drugs with Acesulfame Sweetener

Novel organic salts of norfloxacin and ciprofloxacin with artificial sweeteners such as saccharin and acesulfame were prepared. The two salts 1 and 2 were characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Finally, the crystal structures were solved by single crystal X-ray diffraction data and the structures were analyzed in terms of supramolecular synthons. In norfloxacin acesulfamate 1, two norfloxacin cations and two acesulfame anions form an eight membered cyclic tetramer supramolecular synthon. The salt, ciprofloxacin acesulfamate 2, has a similar structure as salt 1. This study contributes the importance of crystal engineering and supramolecular chemistry to the pharmaceutical applications in terms of interactions and structural correlations in the design of new solid phases.

Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.     

Synthesis and structure of 4,7,13-trioxa-1,10-diaza-5,6-benzocyclopentadecane monohydrate

4,7,13-T4ioxa-1,10-diaza-5,6-benzocyclopentadecane, C₁₄H₂₂N₂O₃·H₂O (7) was synthesized by reduction of macrocyclic diamides (3) or (6). The compound crystallized in the orthorhombic space group Pbca witha=9.361(3),b=9.175(3),c=37.152(11) Å. The structure was solved by direct methods and refined to anR value of 0.048 and wR of 0.038 for 1875 reflections. The molecule itself is internally hydrogen bonded by N–H...O connections. In the crystal structures water molecules form hydrogen bonds with amine nitrogen atoms of adjacent molecules.