Investigation on the silicon network solids and related materials

硅网络固体及相关材料的研究

基本信息

批准号：
11165232
负责人：
MANIWA Yutaka
金额：
$ 16.96万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We investigated silicon network solids and related materials, and obtained the following results.(1) Silicon clathrate superconductor, Ba_8Si_<46> was found to show anomalous behaviors of spin-spin relaxation rate 1/T_2 and Knight shift in the superconducting state.(2) It was confirmed that the sharp large peak of the electronic density of states at the Fermi level is responsible for the occurrence of superconductivity in Si_<46> superconductors. The peak is due to a hybridization between Si and Ba orbitals.(3) A_3C_<60> compounds with large and small lattice constants, such as (NH_3)A_3C_<60>, Na_2AC_<60> and Li_xAC_<60> where A is alkali metals, were systematically investigated by NMR. The t_<1u> orbital degeneracy is important for the stability of the metallic states, and that its splitting and orbital ordering lead to antiferromagnetic ground states.(4) A new layered superconductor, HfNCl, was investigated by NMR and magnetic susceptibility. It was found that HfNCl is a two-dimensional superconductor with a very small density of states at the Fermi level. It was suggested that the superconductivity cannot be explained by the conventional mechanisms.(5) Thermal expansion of MWNT and SWNT was determined by means of x-ray diffraction. MWNT sample grown in hydrogen atmosphere was found to contain a lot of closed Russian doll type tubes for the first time.(6) C_<60> Polymers including Li and Na were investigated by NMR. It was shown that there are sp^3 carbon atoms consistent with proposed structures, and that the alkali ions are moving in the crystals.(7) Alkali-loaded zeolite LTA, whose framework structure is similar to that of the Si46 clathrates, was studied by NMR to clarify the origin of the ferromagnetism at low temperature in this system. The ^<29>Si NMR gave us information on the distribution of the magnetic moments.

我们研究了硅网络固体和相关材料，并获得了以下结果。（1）发现硅纤维超导剂，BA_8SI_ <46>显示出自旋旋转松弛率1/t_2的异常行为1/t_2和骑士在超导向状态中的奈特变化，这是对富尔的峰值的范围。 Si_ <46>超导体中的超导率。峰值是由于Si和Ba轨道之间的杂交引起的。（3）A_3C_ <60>具有大小晶格常数的化合物，例如（NH_3）A_3C_ <60>，Na_2ac_ <60>和Li_xac_ <60> and Li_xac_ <60>，其中A是Alkali Metals n is Alkali Metals nmrs nmrs nmrs nmrs nmrs a as as as a a _3c_ <60>。 T_ <1U>轨道退化对金属状态的稳定性很重要，并且其分裂和轨道秩序导致抗磁磁基态。（4）NMR和磁化性研究了一种新的分层超导体HFNCL，HFNCL。发现HFNCL是一种二维超导体，在费米水平上密度很小。有人提出，超导性无法通过常规机制来解释。（5）MWNT和SWNT的热膨胀是通过X射线衍射来确定的。发现在氢气中生长的MWNT样品首次含有许多封闭的俄罗斯娃娃型管。（6）NMR研究了包括Li和Na在内的C_ <60>聚合物。结果表明，有SP^3碳原子与拟议的结构一致，并且碱离子正在晶体中移动。（7）碱负载的沸石LTA，其框架结构与SI46 Clathrates的框架结构类似于NMR的SI46 Clathrates，以澄清该系统的ferromagnetism systerm in nmer powers in nmer powermagnetism powers。 ^<29> Si NMR向我们提供了有关磁矩分布的信息。