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S. Kazama

Bio: S. Kazama is an academic researcher from Chuo University. The author has contributed to research in topics: Carbon nanotube & Laser linewidth. The author has an hindex of 12, co-authored 45 publications receiving 540 citations.

Papers
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Journal ArticleDOI
Yuh Fukai1, S. Kazama1
TL;DR: In this article, the temperature-dependent activation energy of hydrogen diffusion is deduced from the observed anomaly, and is interpreted as being a manifestation of the gradual change of energy states of hydrogen atoms in approaching the phase transition.

67 citations

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TL;DR: In this article, the temperature dependence of ESR linewidth is ascribed to the Elliott mechanism typical for the metallic electron spins, increasing monotonically with the temperature, which is consistent with the spin susceptibility in polypyrrole doped with ClO 4 − and AsF 6 −.

54 citations

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TL;DR: In this article, a gradual change of d-band of V metal with addition of H(D), and an appearance of h(D)-induced states immediately below the dband, are clearly demonstrated.

46 citations

Journal ArticleDOI
24 Jul 1994
TL;DR: In this article, the chemical structure of the dopants in polythiophene and its derivatives was investigated using Mossbauer nuclei of good resolution, and it was found that the iodine in these polymers exists as linear forms of triiodide and pentaiodide anions.
Abstract: Summary form only given. Polythiophene and its derivatives are highly conducting polymers when doped with appropriate chemical species such as iodine or FeCl/sub 3/. We have investigated the chemical structure of the dopants in these polymers using / sup 129/I and /sup 57/Fe, which are Mossbauer nuclei of good resolution. It has been found that the iodine in these polymers exists as linear forms of triiodide and pentaiodide anions and that the abundance ratio of triiodide decreases with increasing of the doping level. Since the polymers were doped with the iodine of neutral molecules, these anions are created by electron transfer between the polymers and the dopants. Our experimental results are consistent with the proposed mechanism of the electric conductivity which is due to migration of polarons on the polymer chains.

43 citations

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TL;DR: In this paper, the electrical resistivity of poly(3-methylthiophene) doped with PF6− has been studied under pressure up to 13 kbar using a self-clamped beryllium-copper pressure cell.

41 citations


Cited by
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TL;DR: In this paper, the morphological correlation with the charge-carrier mobility in RR P3HT thin-film transistor (TFT) devices is investigated by combining results from atomic force microscopy (AFM) and GIXD.
Abstract: Regioregular poly(3-hexyl thiophene) (RR P3HT) is drop-cast to fabricate field-effect transistor (FET) devices from different solvents with different boiling points and solubilities for RR P3HT, such as methylene chloride, toluene, tetrahydrofuran, and chloroform. A Petri dish is used to cover the solution, and it takes less than 30 min for the solvents to evaporate at room temperature. The mesoscale crystalline morphology of RR P3HT thin films can be manipulated from well-dispersed nanofibrils to well-developed spherulites by changing solution processing conditions. The morphological correlation with the charge-carrier mobility in RR P3HT thin-film transistor (TFT) devices is investigated. The TFT devices show charge-carrier mobilities in the range of 10 - 4 ∼10 - 2 cm 2 V - 1 s - 1 depending on the solvent used, although grazing-incidence X-ray diffraction (GIXD) reveals that all films develop the same π-π-stacking orientation, where the -axis is normal to the polymer films. By combining results from atomic force microscopy (AFM) and GIXD, it is found that the morphological connectivity of crystalline nanofibrils and the -axis orientation distribution of the π-π-stacking plane with respect to the film normal play important roles on the charge-carrier mobility of RR P3HT for TFT applications.

537 citations

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TL;DR: X-ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDT/PSS) as discussed by the authors.
Abstract: X-ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDT/PSS), one of the most common electrically conducting organic pol ...

502 citations

Journal Article
01 Jan 2005-Polymer
TL;DR: In this article, the morphological correlation with the charge-carrier mobility in RR P3HT thin-film transistor (TFT) devices is investigated by combining results from atomic force microscopy (AFM) and GIXD.

494 citations

Journal ArticleDOI
Yimeng Sun1, Peng Sheng1, Chong-an Di1, Fei Jiao1, Wei Xu1, Dong Qiu1, Daoben Zhu1 
TL;DR: A series of metal coordination polymers containing 1,1,2,2-ethenetetrathiolate (ett) linking bridge (poly[Ax(M-ett)]) are synthesized and the TE device fabricated demonstrates the great potentials of these materials for TE applications.
Abstract: A series of metal coordination polymers containing 1,1,2,2-ethenetetrathiolate (ett) linking bridge (poly[Ax(M-ett)]) are synthesized. The Seebeck coefficients of these conducting materials are high, and vary according to the center metals and counter cations. The TE device fabricated demonstrates the great potentials of these materials for TE applications.

433 citations

Journal ArticleDOI
TL;DR: In this article, the stability of double-wall carbon nanotubes is investigated for various chirality pairs, and the potential barrier for the relative displacement of the inner and outer nanotube layers is found to depend significantly on the chiral difference of the pair.

390 citations