Study on the Local Structure of PAN-Based Carbon Fiber Using Radial Distribution Function Based on XRD

2013 ◽  
Vol 664 ◽  
pp. 614-619 ◽  
Author(s):  
Xue Lin ◽  
Cheng Guo Wang ◽  
Mei Jie Yu ◽  
Zhi Tao Lin ◽  
Shan Zhang
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Long Range ◽  
Carbon Fibers ◽  
Radial Distribution ◽  
Local Structure ◽  
Range Order ◽  
Structure Evolution ◽  
Long Range Order ◽  
Rigid Rod

The local structure evolution of polyacrylonitrile (PAN) fibers during pre-oxidation and carbonization was studied using X-ray diffraction (XRD) and radial distribution function (RDF). The nearest inter-chains distance of PAN is 6.88 Å, which is close to the diameter of the “rigid rod” model proposed by Warner. The third neighbor distances of carbon fibers are greater than that of graphite, indicating the planar six-member rings are absent in the carbon fibers from 500 to 1250°C. The structure of fibers transforms from long-range order to long-range disorder during the pre-oxidation process, then transforms from short-range order to long-range order during the carbonization process.

Solid State Structure and Photoluminescence properties of poly(2,5-dialkoxy-p-phenyleneethynylene)s

1995 ◽  
Vol 413 ◽  
Author(s):  
Christoph Weder ◽  
Michael J. Wagner ◽  
Mark S. Wrighton
Keyword(s):  
Solid State ◽  
Long Range ◽  
Photophysical Properties ◽  
Significant Degree ◽  
Range Order ◽  
Quantum Yields ◽  
Side Chains ◽  
Long Range Order ◽  
Rigid Rod ◽  
Covalently Linked

ABSTRACTIn an effort to better understand the relationship between molecular structure and photophysical properties, we have prepared and investigated a series of novel poly(2,5-dialkoxy-p-phenyleneethynylene)s. Wide angle X-ray diffraction measurements show that the supramolecular structure can be easily and significantly influenced by the nature of substituents covalently linked to the rigid-rod polymer main chains. Polymers which have sterically hindered side chains are essentially amorphous, while those with only linear side chains can form lamellar structures with a significant degree of long-range order. High photoluminescence quantum yields, up to 0.86 in solution and 0.36 in the solid state, have been measured. While the solution quantum yields are independent of the functionalization, solid state quantum efficiencies were found to be related to the degree of long-range order in the samples. In samples with a high degree of long-range order, the close proximity of the coplanar oriented polymer backbones is assumed to lead to the formation of eximer complexes which provide non emissive decay channels and, hence, result in comparable low photoluminescence quantum yields. In samples that adopt only a small extent of long-range order, the rigid-rod conjugated polymer backbones behave as if they were ‘dissolved’ in a hydrocarbon solvent and consequently high quantum efficiencies are obtained. Preliminary results indicate the suitability of these polymers as the emitting layer in electroluminescent devices.

Investigation of the local structure of nanosized CdS crystals stabilized with glutathione by the radial distribution function method

2004 ◽  
Vol 45 (3) ◽  
pp. 427-436 ◽  
Author(s):  
V. I. Korsunskii ◽  
R. Neder ◽  
K. Hradil ◽  
J. Neuefeind ◽  
K. Barglik-Chory ◽  
...  
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Local Structure ◽  
Function Method

Synthesis, Characterization and Catalytic Properties of Al2O3-TiO2 Mixed Oxides Prepared by Sol-Gel

1996 ◽  
Vol 431 ◽  
Author(s):  
A. Montoya ◽  
J. Melé;ndez-Hernindez ◽  
J. M. Domínguez ◽  
G. Sandoval-Robles
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Surface Area ◽  
Long Range ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Long Range Order ◽  
Synthesis Parameters ◽  
Mixed Aggregates

AbstractSome synthesis parameters like R-OH/OBu, H20/OBu and composition (Al/Ti) ratios influence the textural and catalytic properties of the mixed Al2O3 -TiO2 oxides. The Radial Distribution Function of the pure and mixed oxides shows that Ti4+ incorporation favors the long-range-order in the mixed aggregates as well as the surface area loss at high temperatures, i.e. 900 °C. The catalytic dehydration of isopropanol towards propylene and the HDS of light gasoils indicate that catalytic properties of the sol-gel mixtures are comparable to the activity of reference catalysts, i.e. Al2O3and Ni/Al2O3.

Medium range order and the radial distribution function

2006 ◽  
Vol 352 (2) ◽  
pp. 116-122 ◽  
Author(s):  
A. Bodapati ◽  
M.M.J. Treacy ◽  
M. Falk ◽  
J. Kieffer ◽  
P. Keblinski
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range
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