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1.
Crystals of the low temperature phase β-Ba3Y(BO3)3 have been synthesized by the flux method. The structure of the title compound crystallizes in the hexagonal system, space group P63cm with the following parameters: a = 9.416(3), c = 17.536(8) A, V= 1346.6(8) A3, Ba3YB3Og,Mr = 677.36, Z = 6, Dc = 5.012 g/cm3, λ(MoKα) = 0.71073 A,μ = 19.409 mm- 1, Flack parameter =0.02(3), F(000) = 1764, R = 0.0714 and wR = 0.1696 for 1076 observed reflections with Ⅰ> 2σ(Ⅰ).The compound contains two sets of YO6 octahedra, four sets of BaO9 polyhedra and three sets of BO3 planar triangles. 相似文献
2.
The effect of nanoclay on the phase-separation behavior of poly(methyl methacrylate)/poly(vinyl acetate)(PMMA/PVAc) blends has been mainly investigated by small-angle laser light scattering. It is found that the effect of clay on the thermodynamics and kinetics of phase-separation for PMMA/PVAc blends seems inconsistent. The kinetics phaseseparation rate decreases, while the thermodynamics parameters, cloud points Tc and delay time tD of isothermal phaseseparation also decrease, and the variation amplitude depends on the matrix composition. The affinity of clay to PMMA results in the composition difference between the border layer and the polymer matrix and further causes the concentration fluctuation at the early stage of phase separation to reduce Tc and tD. On the other hand, the decrease of phase-separation rate is caused by the mechanical barrier effect of clay on the macromolecular diffusion of blend matrix. Hence, such seemingly counterintuitive results on the thermodynamics and kinetics of phase-separation are attributed to different dominant factors. 相似文献
3.
The title compound cis-1,2-dicyano-1,2-bis(2-methyl-4-bromo-3-thienyl)ethane has been synthesized and structurally characterized by X-ray single-crystal diffraction method. Crystal data: triclinic, space group P1^1, Z = 2, C14H8Br2N2S2, Mr = 428.16, a = 6.9410(5), b = 11.0150(9), c = 11.1760(8) A, α = 70.3390(10),β = 76.1860(10), γ = 79.5490(10)°, V= 776.59(10) A^3, Dc = 1.831 g/cm^3, μ(MoKα) = 5.478 mm^-1, F(000) = 416, R = 0.0487 and wR = 0.1453 for 2456 observed reflections with I 〉 2σ(/). X-ray analysis reveals that the two thiophene rings are significantly twisted with an average dihedral angle of 57.45°. The molecule adopts a photo-active antiparaUel conformation and the distance between the two reactive C atoms of thiophene rings is 3.465(8)A. These structural elements which exhibit a suitable geometry are extensively explored for photochromic behavior in the crystalline state. 相似文献
4.
<正>This paper reports the growth,X-ray diffraction and spectroscopy of Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal.A Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal with dimensions ofφ20×45 mm~3 has been grown by the Czochralski method.Nd~(3+):Sr_3Gd_2(BO_3)_4 crystal belongs to the orthorhombic system,space group Pnma(D_(2h))with a=0.7401,b=1.604 and c=0.8755 nm.The absorption and emission spectra of Nd~(3+):Sr_3Gd_2(BO_3)_4 were investigated.The absorption cross sectionσ_a is 3.11×10~(-20)cm~2 at 808 nm. The absorption transition at 808 nm has an FWHM of 14 nm.The luminescence lifetimeτ_f is 51.7 us.The emission cross sectionσ_e at 1064 nm wavelength is 1.09×10~(-19)cm~2. 相似文献
5.
Growth and Characterization of γ—Nd^3+:LaSc3(BO3)4Crystal 总被引:1,自引:0,他引:1
INTRODUCTIONLaser-diode(LD) pumped solid-state lasers have a variety of applications in the fields of military, industry, medical treatment and scientific researches due to the advantages of high stability, compactness, high efficiency and long lifetime, and this area has become one of the hot points in the laser field. As a result, research on new materials with improved spectral properties for diode pumping is of increasing interest again. A new high efficient diode-laser-pumped solid-s… 相似文献
6.
The crystal structure of the title compound (Z)-5-fluoro-3-(phenyl((5-(pyridin-3- ylmethyl)thiophen-2-yl)amino)methylene) indolin-2-one (C25H18FN3OS, Mr = 427.50) has been prepared and determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group P212121 with a = 5.931(1), b = 12.413(1), c = 28.102(2) A, V= 2090.4(3) A3, Z = 4, Dc = 1.358 g/cm3, F(000) = 888, μ= 0.186 mm-1, MoKa radiation (2 = 0.71073), R = 0.041 and wR = 0.105 for 4567 observed reflections with I 〉 2σ(I). X-ray diffraction analysis reveals that the indole and thiophene rings are not coplanar with a dihedral angle of 46.26(5)°. Intramolecular and intermolecular N-H'..O hydrogen bonds together with C-H...π interations can be observed in the lattice. 相似文献
7.
In the present work, the PLLA mesophase formation and its kinetics at the advent of a chain mobility accelerator (polyethylene glycol (PEG)) are investigated by wide angle X-ray diffraction (WAXD) and time-resolved Fourier transform infrared spectroscopy (FTIR). It is interestingly found that the presence of PEG could accelerate the formation of PLLA mesophase notably due to the enhanced chain mobility, giving rise to a substantially reduced half time (t0.5) of PLLA mesophase formation from 129 min to 8 min. The Avrami exponents (n) for the kinetics of mesophase formation are -0.5 for neat PLLA and 1 for PLLA/PEG, respectively, indicating that 1D-rod growth through heterogeneous nucleation occurs during formation of PLLA mesophase. Tensile testing demonstrates that PLLA mesophase could increase the tensile strength and modulus but decrease the elongation at break. 相似文献
8.
LI Wen-Ming WANG Jian-Guo ② GUO Wan-Cheng LI Zheng-Ming SONG Hai-Bin 《结构化学》2008,27(6):691-696
The title compounds (S)-methyl-2-(4-R-phenylsulfonamido)-3-(1H-indol-3- yl)propanoate (R = H (1), Cl (2)) have been synthesized and their crystal structures also have been determined by X-ray single-crystal diffraction. Compound 1 (C18H18N2O4S) belongs to orthorhombic, space group P212121 with a = 9.6348(14), b = 11.1517(17), c = 16.412(3) A, V = 1763.4(5) A^3, Mr = 358.40, Z = 4, De = 1.350 g/cm^3,/t = 0.209 mm^-1, F(000) = 752, R = 0.0348 and wR = 0.0714. Compound 2 (CI8H17ClN2O4S) crystallizes in orthorhombic, space group P212121 with a = 9.3128(14), b = 10.9655(16), c = 17.783(3) A, V = 1815.9(5) A^3, Mr = 392.85, Z = 4, De = 1.437 g/cm^3, p = 0.352 mm^-1, F(000) = 816, R = 0.0389 and wR = 0.0845. The absolute structure Flack parameters X of compounds 1 and 2 are -0.03(8) and -0.06(7), respectively. X-ray analysis reveals that the crystal structures of these two compounds both involve two intermolecular N-H…O hydrogen bond's. 相似文献
9.
A novel coordination polymer of [Zn(4-CPOA)(Phen)(H2O)]n (C21H16N2O6Zn,1,4-CPOA = 4-carboxylato-phenoxyacetate dianion and Phen = 1,10-phenanthroline) has been synthesized and characterized by elemental analysis,IR,TG,PL and single-crystal X-ray diffraction. The crystal crystallizes in the triclinic system,space group of P1 with a = 9.622(3),b = 9.631(3),c = 11.526(4)A,α = 67.719(5),β = 71.203(5),γ = 83.552(6)o,V = 935.5(5) A^3,Z = 2,Dc = 1.625 g/cm^3,μ = 1.357 mm^-1 and F(000) = 468. The Zn(II) ion is surrounded by three carboxylate O atoms from two different 4-CPOA groups,two N atoms from the Phen ligand and one water molecule,forming a distorted octahedral coordination configuration. The Zn(II) ions were alternately interlinked by carboxylate groups of 4-CPOA with chelating bisbidentate and monodentate modes into a one-dimensional zigzag chain having an intrachain distance of ca. 9.631(1) . Under the direction of supramolecular recognition and attraction,the adjacent chains yield a double-stranded chain through π-π stacking between the phen ligands,which was further expanded into a 2-D framework via strong C–H–π interaction (ca. 2.95(1) ) between the 4-CPOA ligands and into a 3-D supramolecular network by strong hydrogen bond between terminal water molecule and carboxyl group. TG/DTG shows that its chain skeleton is thermally stable up to 419 oC and the blue fluorescent emission of the complex was determined at 471 nm in a solid state with its long decay lifetime of 1.83 ns. 相似文献
10.
A new polyoxomolybdate compound,namely {[MnII(L)(4,4?-Hbipy)(H2O)2]2 [Mo5O15(PO4)2]}.2H2O 1(L = 3-(2-pyridyl)pyrazole,4,4'-Hbipy = protonated 4,4'-bipyridine),was designed and synthesized under hydrothermal conditions.Single-crystal X-ray diffraction analysis result reveals that the [Mo5O15(PO4)2]6-cluster in compound 1 links to two MnII cations via the oxygen of PO43-,which is further coordinated by one 3-(2-pyridyl)pyrazole,one 4,4'-Hbipyridine,and two water molecules. 相似文献
11.
Time-resolved infrared spectroscopy has been used to study the melt crystallization behavior of poly(3-octylthiophenes) (P3OT), which is a typical conductive polymer among the family of poly(3-alkylthiophenes) (P3ATs). It is found that, during the isothermal crystallization process at high temperature, the alkyl side chains of P3OT always keep in disordered state, whereas the ordering packing of conjugated backbone takes place. In order to reveal the structural changes and the crystallization kinetics corresponding to the main-chain ordering process, two spectral regions that associated with π–π stacking and the effective conjugation length of P3OT have been analyzed in detail. The characteristic IR bands of crystalline and amorphous phase are identified in each spectral region. Moreover, a simple spectral method has been proposed to calculate the evolution of crystallinity during the isothermal crystallization process of P3OT. Of particular note, the distinct one-dimensional growth kinetic of P3OT crystal has been revealed by Avrami analysis. 相似文献
12.
The morphology and mechanical properties of poly-(3-octylthiophene) P3OT films thin has been studied by scanning force microscopy techniques. On these films we find self-assembled layered structures that appear regardless of the preparation conditions, that is, spin-coating or drop-casting, of the solvent concentration or of the type of substrate. Using the drop-casting method for sample preparation these layered structures are hardly visible due to the high surface roughness, while using spin-coating these structures are the main topographic feature on the surface. These structures have typically one or two layers, even though occasionally up to four layers have been observed. Each layer has a height of 4-5 nm, which is associated to crystalline P3OT domains and lay on the polymer film. The size of these structures increases with increasing concentration of the P3OT in the solvent. We find well differentiated morphological, electrostatic as well as mechanical properties for the self-assembled structures as compared to the rest of the polymer film. Finally, the growth rate of these structures has been studied. 相似文献
13.
K. Levon E. Chu K.-S. Ho T. K. Kwei J. Mao W.-Y. Zheng J. Laakso 《Journal of Polymer Science.Polymer Physics》1995,33(4):537-545
The mixing of electrically conducting polymers in the undoped state with flexible polymers has been limited due to the stiffness of the delocalized coplanar backbone. The substitution with alkyl side chains has resulted in the distortion of the aromatic rings in the backbone with an increase of the flexibility. The alkyl substituents also prevent the thiophene back-bones from packing together, thus making blending with other polymers promising. We have investigated the phase behavior of poly(3-octylthiophene) (P3OT) with a flexible polymer, poly(ethylene-co-vinylacetate) (vinylacetate composition 20%, EVA20), and defined a miscibility window based on melting point data, on cloud point measurements, and on analysis by optical microscopy. The miscible region has been studied by UV-VIS and CPMAS NMR spectroscopies. A UV absorption in the visible region originates from a π-π * transition in the delocalized structure of P3OT, and a change in the length of the conjugated segment in the backbone results in a shift of this absorption. A gradual solvatochromatic shift of P3OT in the solid state with dilution was observed in the miscible region. T1 relaxation times for the methylene carbons in solid state show a gradual change in the relaxation process as a function of composition. © 1995 John Wiley & Sons, Inc. 相似文献
14.
V. V. Kurdakova N. G. Antonov V. V. Malev V. V. Kondrat’ev 《Russian Journal of Electrochemistry》2006,42(4):299-305
The results of a study of poly(3-octylthiophene) films with the aid of an electrochemical quartz microbalance are presented. The effect of the nature of the electrolyte anion on the determined weights of mobile species that are transported through the film/electrolyte interface is discussed. The obtained results point to a substantial role played by the solvent transport in the course of the electrode reaction. The results concerning the influence exerted by the electrode material on the observed regularities are presented. 相似文献
15.
U. León-Silva M. E. Nicho J. G. González-Rodríguez J. G. Chacón-Nava V. M. Salinas-Bravo 《Journal of Solid State Electrochemistry》2010,14(6):1089-1100
The effect of thermal annealing of poly(3-octylthiophene) (P3OT) coatings on the corrosion inhibition of stainless steel in
an NaCl solution was investigated. P3OT was synthesized by direct oxidation of the 3-octylthiophene monomer with ferric chloride
(FeCl3) as oxidant. P3OT films were deposited by drop-casting technique onto 304 stainless steel electrode (304SS). 304SS coated
with P3OT films were thermally annealed during 30 h at different temperatures (55°C, 80°C, and 100°C). The corrosion resistance
of stainless steel coated with P3OT in 0.5 M NaCl aqueous solution at room temperature was investigated by using potentiodynamic
polarization curves, linear polarization resistance, and electrochemical impedance spectroscopy. The results indicated that
the thermal treatment at 80°C and 100°C of P3OT films improved the corrosion resistance of the stainless steel in NaCl solution;
the speed of corrosion diminished in an order of magnitude with regard to the 304SS. In order to study the temperature effect
in the morphology of the coatings before and after the corrosive environment and correlate it with corrosion protection, atomic
force microscopy and scanning electron microscopy were used. Morphological study showed that when the films are heated, the
grain size increased and a denser surface was obtained, which benefited the barrier properties of the film. 相似文献
16.
17.
Stefopoulos AA Chochos CL Prato M Pistolis G Papagelis K Petraki F Kennou S Kallitsis JK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(28):8715-8724
Facile routes for the synthesis of hybrid materials consisting of regioregular poly(3-octylthiophene)s covalently attached to single-wall carbon nanotubes are presented for the first time. These materials are easily processable using common organic solvents, and at the same time combine the properties of regioregular poly(3-alkylthiophene)s with those of single-wall carbon nanotubes. Moreover, studies of the properties of these materials have provided strong evidence for an electron transfer from the regioregular poly(3-octylthiophene) to the single-wall carbon nanotube. 相似文献
18.
Mercedes Vázquez Johan Bobacka Ari Ivaska 《Journal of Solid State Electrochemistry》2005,9(12):865-873
Potentiometric ion sensors were prepared from the conjugated polymer poly(3-octylthiopene) (POT). The influence of additional
membrane components, including silver 7,8,9,10,11,12-hexabromocarborane (AgCB11H6Br6) and potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (KTpFPB) as lipophilic salts, and [2.2.2]p,p,p-cyclophane as silver ionophore, was studied. The membrane components were dissolved in chloroform and membranes were prepared
by solution casting on glassy carbon disk electrodes. For comparison, POT-based potentiometric sensors were also prepared
by galvanostatic electrosynthesis of POT from the 3-octylthiophene monomer. All the POT-based ion sensors fabricated by solution
casting show Nernstian or slightly sub-Nernstian response to Ag+, even those based only on POT without any additional membrane components. The potentiometric response of electrochemically
polymerized POT depends on the film thickness and the doping anion incorporated in the conducting polymer during polymerization.
It is of particular importance that chemically synthesized undoped POT (without any additives) shows a sensitive and selective
potentiometric response to Ag+ ions although UV-vis results show that POT remains in its undoped form, i.e., POT is not oxidized by Ag+. This indicates that undoped POT can exhibit good sensitivity and selectivity to Ag+ also in the absence of metallic silver in the polymer film. In this case, the potentiometric response is related to interactions
between Ag+ and the conjugated polymer backbone.
Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, 13–16, 2005 相似文献
19.
20.
Structural transitions of nanocrystalline domains in regioregular poly(3‐hexyl thiophene) thin films
Hoichang Yang Tae Joo Shin Zhenan Bao Chang Y. Ryu 《Journal of Polymer Science.Polymer Physics》2007,45(11):1303-1312
The effects of solution processing and thermal annealing on thin film morphology and crystalline structures of regioregular poly(3‐hexyl thiophene) (RR P3HT) are studied in terms of molecular weight (Mw). Using grazing‐incidence X‐ray diffraction, π‐conjugated planes in drop‐cast films from chloroform solutions are found to be preferentially oriented parallel to the substrates regardless of Mw. However, the mesoscale nanocrystalline morphology of the drop‐cast films is significantly affected by Mw, exhibiting a distinctive morphological transition from short nanorods to long nanofibrils above a critical number‐averaged Mw (~ 3.6 kDa). This is probably due to the change in a conformation change from an extended‐chain to a folded‐chain, as Mw of RR P3HT increases. In contrast, spin‐casting of high Mw RR P3HT produces less ordered films with a lower crystallinity and mixed parallel/perpendicular orientations of π‐conjugated planes. The crystallinity and parallel π‐conjugated orientation of RR P3HT in spin‐cast films could be improved by thermal treatments at high‐temperatures either (1) above the glass transition temperature or (2) above the melting temperature of RR 3PHT followed by recrystallization upon cooling under vacuum. However, the charge mobility of the spin‐cast films for a field‐effect transistor application is still lower than that of the drop‐cast films. This would be attributed to the chain oxidation and the development of distinct grain boundaries between RR P3HT nanofibrils during the thermal treatments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1303–1312, 2007 相似文献