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Structural Ordering (structural + ordering)
Selected Abstracts2,7-Carbazolenevinylene-Based Oligomer Thin-Film Transistors: High Mobility Through Structural Ordering,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2005N. Drolet Abstract We have fabricated organic field-effect transistors based on thin films of 2,7-carbazole oligomeric semiconductors 1,4-bis(vinylene-(N -hexyl-2-carbazole))phenylene (CPC), 1,4-bis(vinylene-(N,-methyl-7,-hexyl-2,-carbazole))benzene (RCPCR), N -hexyl-2,7-bis(vinylene-(N -hexyl-2-carbazole))carbazole (CCC), and N -methyl-2,7-bis(vinylene-(7-hexyl- N -methyl-2-carbazole))carbazole (RCCCR). The organic semiconductors are deposited by thermal evaporation on bare and chemically modified silicon dioxide surfaces (SiO2/Si) held at different temperatures varying from 25 to 200,°C during deposition. The resulting thin films have been characterized using UV-vis and Fourier-transform infrared spectroscopies, scanning electron microscopy, and X-ray diffraction, and the observed top-contact transistor performances have been correlated with thin-film properties. We found that these new ,-conjugated oligomers can form highly ordered structures and reach high hole mobilities. Devices using CPC as the active semiconductor have exhibited mobilities as high as 0.3,cm2,V,1,s,1 with on/off current ratios of up to 107. These features make CPC and 2,7-carbazolenevinylene-based oligomers attractive candidates for device applications. [source] Synthesis and Properties of Al-Ni-La Bulk Metallic Glass,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Juan Mu Al85.5Ni9.5La5 bulk metallic glass (BMG) with a size of 1,mm is synthesized for the first time through a two-step melt treatment. The treatment effectively removes the local structural ordering and high-temperature phases, as well as allowing a high cooling rate. The sample displays good mechanical properties. The compressive fracture strength is about 1180,MPa, which is higher than that of most Mg-based BMGs and Al alloys. [source] High-Performance Single Crystal Organic Field-Effect Transistors Based on Two Dithiophene-Tetrathiafulvalene (DT-TTF) PolymorphsADVANCED MATERIALS, Issue 37 2010Raphael Pfattner Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the ,-phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules. [source] FePt thin film irradiated with high energy ionsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007M. Jaafar Abstract The changes in structural and magnetic properties of FePt thin films due to the irradiation with high energy ions (Br7+ and Cl2+) were studied. From the hysteresis loops dominating in-plane anisotropy is derived, however, the samples present a minor out-of-plane component. The structure and the magnetic properties of the films can be tuned by selecting the appropriate irradiation parameters (different ions, energies and fluencies). For the irradiation parameters used in this study an in-plane anisotropy is favoured. Irradiation with Br7+ seems to induce minor changes in the structural ordering of the thin films, whereas the Cl2+ ions promote the amorphization of the surface of the films. In addition, a magnetic thin film patterned at the micrometer scale was obtained after irradiation through a micrometric mask. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] 3-Nitrophenol,4,4,-bipyridyl N,N,-dioxide (2/1): a DFT study and CSD analysis of DPNO molecular complexesACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Rodolfo Moreno-Fuquen The title 2:1 complex of 3-nitrophenol (MNP) and 4,4,-bipyridyl N,N,-dioxide (DPNO), 2C6H5NO3·C10H8N2O2 or 2MNP·DPNO, crystallizes as a centrosymmetric three-component adduct with a dihedral angle of 59.40,(8)° between the planes of the benzene rings of MNP and DPNO (the DPNO moiety lies across a crystallographic inversion centre located at the mid-point of the C,C bond linking its aromatic rings). The complex owes its formation to O,H...O hydrogen bonds [O...O = 2.605,(3),Å]. Molecules are linked by intermolecular C,H...O and C,H...N interactions forming R21(6) and R22(10) rings, and R66(34) and R44(26) macro-rings, all of which are aligned along the [01] direction, and R22(10) and R21(7) rings aligned along the [010] direction. The combination of chains of rings along the [01] and [010] directions generates the three-dimensional structure. A total of 27 systems containing the DNPO molecule and forming molecular complexes of an organic nature were analysed and compared with the structural characteristics of the dioxide reported here. The N,O distance [1.325,(2),Å] depends not only on the interactions involving the O atom at the N,O group, but also on the structural ordering and additional three-dimensional interactions in the crystal structure. A density functional theory (DFT) optimized structure at the B3LYP/6-311G(d,p) level is compared with the molecular structure in the solid state. [source] Spin-Crossover Physical Gels: A Quick Thermoreversible Response Assisted by Dynamic Self-OrganizationCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2007Tsuyohiko Fujigaya Abstract Iron(II) triazolate coordination polymers with lipophilic sulfonate counterions with alkyl chains of different lengths have been synthesized. In hydrocarbon solvents, these polymers formed a physical gel and showed a thermoreversible spin transition upon the sol,gel phase transition. The formation of a hydrogen-bonding network between the triazolate moieties and sulfonate ions, bridged by water molecules, was found to play an important role in the spin-crossover event. The spin-transition temperature was tuned over a wide range by adding a small amount of 1-octanol, a scavenger for hydrogen-bonding interactions. This additive was essential for the iron(II) species to adopt a low-spin state. Compared with nongelling references in aromatic solvents, the spin-crossover physical gels are characterized by their quick thermal response, which is due to a rapid restoration of the hydrogen-bonding network, possibly because of a dynamic structural ordering through an enhanced lipophilic interaction of the self-assembling components in hydrocarbon solvents. [source] | |||||||||||||