2004 Fiscal Year Final Research Report Summary
IONIC CONDUCTORS IN THE FORM OF WELL-ORDERED NANO-CHANNELS AND THEIR NOVEL FUNCTIONAL PROPERTIES
| Project/Area Number |
15510097
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanomaterials/Nanobioscience
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| Research Institution | Tohoku University |
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Principal Investigator |
MAEKAWA Hideki Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (60238847)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMURA Tsutomu Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (80005363)
SATO Yuzuru Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (80108464)
KAWAMURA Junichi Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Professor, 多元物質科学研究所, 教授 (50142683)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Ionic conductor / Mesoporous material / Nano-composite / Lithium ion / Proton / Self-assembly / Size-effect |
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| Research Abstract |
The purpose of the present investigation is to prepare nano-channeled ceramics including Al_2O_3, SiO_2 and ZrO_2 with various pore sizes by means of sol-gel synthesis, and to investigate conductivity and diffusive properties of protons and lithium ions confined within mesosized space, aiming for development of novel ionic functional properties.
Powdered mesoporous ceramics with various pore sizes was prepared by the sol-gel method utilizing neutral surfactants as structure-directing agent. The N_2 adsorption and desorption isotherms of the mesoporous-Al_2O_3 were Type IV, with a small hysteresis that indicates a minor deviation from a regular array of cylinders. A sharply peaked distribution was observed reflecting a uniform mesopore size controlled from 3 to 22 nm. The dc conductivity for 0.5(mesoporous-Al_2O_3 (pore size=4nm))-0.5LiI composite increased with increasing mesoporous-Al_2O_3 content up to x=0.5. The maximum conductivity was 2.6×10^<-4>S cm^<-1> at 298 K, which is more th
… More
an 1000 times as high as that of pure LiI, and more than 10 times improvement was achieved compared to previously reported LiI-Al_2O_3 composite. A systematic pore size dependence of the conductivity was observed. The conductivity increased with decreasing pore size except for pore size=2.8 nm.
High protonic conductivity of 1% LaCl_3 doped mesoporous-Al_2O_3 samples with different mesopore size ranging from 3.7 nm to 15.8 nm was discovered. The highest conductivity was obtained 0.004S・cm^<-1> at 25℃ which is approaching that of Nafion. It is clear that the conductivity increased with increasing the pore size monotonically. To the best of our knowledge, this is a first demonstration of the systematic pore size dependence upon protonic conduction of the porous media. From the TG/DTA and ^1H NMR, the conduction mechanism was attributed hopping of protons in the water layer. We categorize proton species into three groups, physically absorbed water (group I), water molecules bound to surface OH groups (group II) and surface OH groups (group III). We assume the major species for ionic conduction is due to protons of group II. From NMR, group II protons have close relation with the NUR observed"mobile"protons. On the other hand, the polymer composite with this mesoporous alumina powders by utilizing silan-coupling reagent (LS-3380) and polymerization with AMPS, MBAA and MA yields whitish membrane composite. This polymer composite did not show any change under treatment at 100℃ for one week and shows a protonic conductivity in the range of 10^<-5> Scm^<-1>. Less
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Research Products
(13 results)
