Search for High Critical Temperature Superconductivity in Li- or Mg-doped Boron Icosahedral Cluster Solids

寻找锂或镁掺杂硼二十面体团簇固体的高临界温度超导性

• 批准号: 15360332
• 负责人: KIMURA Kaoru
• 金额: $ 9.79万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360332/
• 关键词: superconductor; boron-rich semiconductor; icosahedral cluster; high symmetry; doping; variable-range hopping conduction; Pauli naramagnetic; structurally complex material

There is a possibility of high-Tc superconductivity upon metallic-element doping into β-rhombohedral boron (β-B^<105>), which is one of the boron icosahedral cluster solids. We attempted magnesium (Mg) doping into β-B^<105> and discussed the possibility of metal and superconductive transitions. We achieved a higher concentration of Mg doping into β-B^<105>, up to MgB_<11.5> (8.6 Mg/cell), i.e., electron doping sufficient for the Fermi energy (E_F) to reach over the intrinsic accepter level (IAL). However, neither metal nor superconductive transition was observed. The change in the structure and electronic properties are discussed on the basis of the X-ray powder diffraction (XRD), using the Rietveld method, and electrical conductivity and magnetic susceptibility measurements, respectively. We estimated the density of states (DOS) at the E_F and discussed the electronic states of β-B^<105>. As a result, it is suggested that a localized state exists above the IAL probably originating from B28 cluster with structural defects.We measured electrical conductance of single crystalline boron nanobelts having α-tetragonal crystalline structure. The doping experiment of Mg was carried out by vapor diffusion method. The pure boron nanobelt is a p-type semiconductor and its electrical conductivity was estimated to be on the order of 10^<-3> (Ωcm)^<-1> at room temperature. The carrier mobility of pure boron nanobelt was measured to be on the order of 10^<-3> (cm^2/Vs) at room temperature and has an activation energy of 〜0.19 eV. The Mg-doped boron nanobelts have the same α-tetragonal crystalline structure as the pristine nanobelts. After Mg vapor diffusion, the nanobelts were still semiconductor, while the electrical conductance increased by a factor of 100〜500. Transition to metal or superconductor by doping was not observed.

在硼二十面体团簇固体β-菱面体硼（β-B^）中掺杂金属元素有可能实现高温超导<105>。我们尝试将镁（Mg）掺杂到β-B^中<105>，并讨论了金属和金属间化合物转变的可能性。我们实现了更高浓度的Mg掺杂到β-B_（1）中<105>，高达Mg B_<11.5>（8.6 Mg/电池），即，电子掺杂足以使费米能（E_F）达到本征受主能级（IAL）以上。然而，既没有观察到金属也没有观察到过渡。的结构和电子性质的变化进行了讨论的基础上的X射线粉末衍射（XRD），使用Rietveld方法，和电导率和磁化率测量，分别。我们计算了E_F处的态密度，讨论了β-B^的电子态<105>.结果表明，在IAL上存在一个局域态，可能起源于具有结构缺陷的B28团簇。我们测量了具有α-四方晶系结构的单晶硼纳米带的电导。采用气相扩散法进行了Mg的掺杂实验。纯硼纳米带是p型半导体，并且其电导率估计在室温下为10^<-3>（Ωcm）^的量级<-1>。纯硼纳米带的载流子迁移率在室温下测量为10^<-3>（cm^2/Vs）的量级，并且具有约0.19 eV的激活能。Mg掺杂的硼纳米带具有与原始纳米带相同的α-四方晶系晶体结构。镁蒸气扩散后，纳米带仍为半导体，但电导率增加了100〜500倍。没有观察到通过掺杂向金属或超导体的过渡。

项目成果

Temperature dependence of electrical conductance in single-crystalline boron nanobelts

• DOI: 10.1063/1.1935036
• 发表时间: 2005-05
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: K. Kirihara;Z. Wang;Kenji Kawaguchi;Y. Shimizu;T. Sasaki;N. Koshizaki;K. Soga;K. Kimura

High Energy-resolution Electron Energy-loss Spectroscopy Study of the Electronic Structures of <Li-> and Mg-doped α-rhombohedral Boron

<Li->和镁掺杂α-菱面体硼电子结构的高能量分辨率电子能量损失谱研究

• 发表时间: 2004
• 期刊: Journal of Electron Microscopy 53
• 作者: M.TERAUCHI;K.KIMURA et al.
• 通讯作者: K.KIMURA et al.

熱電変換材料

热电转换材料

• 发表时间: 2007

Electrical transport of tetragonal boron nanobelts

• DOI: 10.1116/1.2131870
• 发表时间: 2005-11
• 期刊: Journal of Vacuum Science & Technology B
• 影响因子: 1.4
• 作者: K. Kirihara;Z. Wang;Kenji Kawaguchi;Y. Shimizu;T. Sasaki;N. Koshizaki;H. Hyodo;K. Soga;K. Kimura

High Energy-resolution Electron Energy-loss Spectroscopy Study of the Electronic Structures of Li-and Mg-doped α-rhombohedral Boron

锂和镁掺杂α-菱面体硼电子结构的高能量分辨率电子能量损失谱研究

• 发表时间: 2004
• 期刊: Journal of Electron Microscopy 53
• 作者: M.TERAUCHI;A.OGURI;K.KIMURA;A.FUJIWARA
• 通讯作者: A.FUJIWARA