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Development of Novel Guest Phases Confined in Carbon Based Micropore Space and Their Properties

碳基微孔空间新型客体相的开发及其性能

基本信息

批准号：
08404048
负责人：
ENOKI Toshiaki
金额：
$ 26.05万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1999
项目状态：
已结题

项目摘要

(1) Nano-graphite derived by the heat-treatment of nano-diamond is investigated in relation to their structures, electronic structures and host-guest systems with potassium and bromine. From Raman spectra and X-ray diffraction, it is found that nano-diamond is converted to nano-graphite around 1600℃. Nano-graphite thus obtained has a novel electronic structure featured with non-bonding π-electron states of edge origin. The non-bonding edge states play an important role in the spin-lattice relaxation mechanism as fast relaxation centers at the edges. The spin-lattice relaxation process is decelerated in less graphitized particles prepared at lower temperatures around 1200℃, which can be explained by the presence of remnant spィイD13ィエD1 regions. Intercalation of potassium makes edge states less important in the electronic structure due to charge transfer from potassium to graphite. The presence of potassium works to enhance the spin-orbit interaction.(2) The electronic properties of activated carbon fibers are investigated, which consist of disordered network of nano-graphite. Heat-treatment induces an insulator-to-metal transition around 1300℃, due to the development of infinite percolation path networks. In the insulating state, the charging effect works importantly in the electron hopping process, while the metallic state is featured with a considerable amount of disorder. In the vicinity of the insulator-to-metal transition, spin-glass-like disordered magnetism appears where spins of edge-inherited non-bonding states are interacting with the aid of π-conduction-electron mediated interaction. Physisorption of water molecules in micropores surrounding nano-graphite domains induces a reduction of the spin concentration. This can be explained in terms of the enhancement of inter-nano-graphite interaction induced by the effective pressure of introduced water molecules.

(1)研究了纳米金刚石热处理后得到的纳米石墨的结构、电子结构以及与钾和溴的主客体体系。拉曼光谱和x射线衍射结果表明，纳米金刚石在1600℃左右转变为纳米石墨。由此得到的纳米石墨具有边缘原点非键π电子态的新颖电子结构。非键边缘态作为边缘的快速弛豫中心，在自旋晶格弛豫机制中起着重要作用。spin-lattice弛豫过程减速在石墨化粒子准备在较低的温度约1200℃,可解释为遗迹的存在spィイD13ィエD1地区。由于电荷从钾转移到石墨，钾的插入使得边缘态在电子结构中不那么重要。钾的存在增强了自旋轨道相互作用。(2)研究了由纳米石墨无序网络构成的活性炭纤维的电子性能。由于无限渗透路径网络的发展，热处理在1300℃左右诱导绝缘体到金属的转变。在绝缘状态下，充电效应在电子跳变过程中起着重要的作用，而在金属状态下则具有相当大的无序性。在绝缘体到金属跃迁的附近，出现了自旋玻璃状的无序磁性，其中边缘继承的非键态的自旋借助于π-传导-电子介导的相互作用相互作用。水分子在纳米石墨畴周围微孔中的物理吸附导致自旋浓度降低。这可以用引入水分子的有效压力诱导纳米石墨间相互作用的增强来解释。