Search for Novel Carbon Based Nanonetwork Materials and their Properties

(1)碳纳米管与碱金属的插层过程单壁碳纳米管(SWNT)的可能应用之一是锂离子电池的负极。通过拉曼光谱、红外光谱、X射线光电子能谱等手段揭示了插层过程。首先，碱金属被插入到由三个管包围的间隙位置，然后插入到两个管之间的较小位置，导致管间距严重膨胀。(2)富勒烯反铁磁体的分子取向和磁结构我们通过将中性氨分子插层到A_3C_(60)超导体中，系统地合成了(NH_3)A_3C_&lt；60&gt；，发现所有的单氨化化合物都是反铁磁性绝缘体。(NH_3)A_3C_&lt；60…More&gt；采用由A_3C60的面心立方晶胞轻微变形产生的正交晶胞，由于这种变形，电子局域在C_lt；60&gt；部分上。此外，还用核磁共振和中子散射实验确定了其磁结构和分子取向。它们之间的关联性与过渡金属氧化物磁体中轨道和自旋有序之间的关系很好地相似，即卡纳森-古德足够规则。(3)研究了稀土金属掺杂富勒烯与稀土金属的插层作用。其中，我们成功地合成了单相Sm_3Ct；70和Gt；，并通过MEM/Rietveld分析在电子密度水平上确定了晶体结构。研究发现，Sm离子连接了相邻的两个C&lt；70&gt；基团，形成了一种新型的二聚体结构。这种二聚体结构相当稳定，因为这种结构至少可以保持到850K，而传统富勒烯聚合物中的键断裂表现为600K以下的键断裂。(4)La@C_&lt；82&gt；薄膜的介电性能我们制备了金属富勒烯La@C_&lt；82&gt；薄膜，并测量了介电常数随温度的变化。室温下的介电常数约为40，约比C_(60)的介电常数(4.4)大一个数量级。相当大的介电常数可能是由于具有较大介电矩的分子的旋转所致。La@C&lt；82&gt；的这种偶极活性可能表明分子的旋转态可以由外加电场控制。较少

(1) Intercalation processes of carbon nanotubes with alkali metalsOne of the possible application of single walled carbon nanotubes (SWNT) is the anode of the Li ion batteries. We have uncovered the intercalation processes by means of the spectroscopic methods, such as Raman, infrared, and XPS. First, alkali metals are inserted into interstitial sites surrounded by three tubes, followed by an insertion into the smaller site between two tubes, causing a serious expansion of the intertube distances. Until this state, A3C80, the concentration of alkali metals increases continuously, but displays a discontinuous jump to A9C80, above which the A concentration shows a continuous increase again.(2) Molecular orientations and magnetic structures in fullerene antiferromagnetsWe have systematically synthesized (NH_3)A_3C_<60>, by intercalating neutral ammonia molecules into A_3C_<60> superconductors, and found that all the monoammoniated compounds are antiferromagnetic insulators. (NH_3)A_3C_<60 … More > adopts an orthorhombic unit cell derived by a slight deformation of the fcc cell of A_3C60, and because of this deformation, the electron is localized on the C_<60> moiety. Furthermore, the magnetic structure and molecular orientations have been determined by NMR, and neutron scattering experiments, respectively. The correlation between these displays a nice analogy to the relation between the orbital and spin orderings in transition metal oxides magnets, which is known as Kanamori-Goodenough rule.(3) Novel dimer structure in rare earth metal doped fulleridesIntercalation of fullerenes with rare earth metals has been investigated. Among these, we succeeded in synthesizing single phase Sm_3C_<70>, and in determining the crystal structure in a electron density level, by means of MEM/Rietveld analysis. It was found that two neighboring C_<70> moieties are connected by the Sm ion, forming a new type of dimer structure. This dimer structure is considerably stable, because the structure is maintained at least up to 850K, in contrast to the bond breaking in the conventional fullerene polymers showing a bond breaking below 600K.(4) Dielectric properties of La@C_<82> thin filmsWe have fabricated thin films of the metallofullerene La@C_<82>, and measured dielectric constants as a function of temperature. The dielectric constant at room temperature is about 40, approximately one order larger than that of C_<60> (4.4). The considerably large dielectric constant is presumably due to the rotation of the molecules with a large dielectric moment. Such dipolar activity of La@C_<82> might suggest that the molecular rotation states could be controlled by the external electic field. Less